DAIRY REPRODUCTION

Feeding, Health and Reproduction
Gordon King, Animal & Poultry Science, University of Guelph
Feeding Dairy Cattle

Forages

Dairy cattle consume a wide variety of forages in the form of grasses, legumes, corn and other green plants। These may be ingested as pasture, green chop, silage, haylage, hay or crop residues (straw, stover). High quality forages, determined by the nutrient content, digestibility and palatability of the plants, can improve productivity through reducing feed expenses and promoting efficient rumen function. When plants reach advanced stages of maturity, much of the hemicellulose-cellulose forming the cell walls is converted to lignin. This substance is almost totally indigestible by most organisms so mature plant yield considerably fewer nutrients than young, actively growing plants. Poor forage quality can be compensated for by feeding more cereal grains and protein supplements. However, excessive grain feeding is expensive and, if carried to extremes, may produce digestive disturbances.

Government supported or privately operated forage analysis laboratories function wherever intensive dairying occurs so the precise chemical composition and digestibility of feed ingredients can be determined. Farmers must be cautious, however, since proximate analysis, the most common form available, provides values on composition of the material tested but these do not usually indicate how much the consuming animal obtains when the material is fed. Accurate information on palatability and digestibility is essential before intake can be estimated and rations balanced.
Forage feeding methods range from grazing through traditional hand dispensing in older tie-stall barns to sophisticated, automated systems for those willing to invest in the latest technology.
The recent increase in cost for energy and concentrate feeds creates a need for better utilization of forages and a renewed interest in pasture-based dairying. Considerable information about pasture-based dairying is available on the Internet.

• Concentrates
  These ingredients represent relatively concentrated sources of energy or protein. Some additional processing such as rolling or grinding of cereals is often necessary to improve digestibility. Proper amounts of concentrate can only be determined after forage quality is known. Stage of lactation or growth must also be considered to calculate and dispense sufficient nutrients for maintenance and production (a generalization for early to mid lactation animals might be about 0.4 kg of concentrate per kg of milk).
  A substantial proportion of the high biological efficiency obtained currently with dairy cows results from feeding by-pass nutrients. If concentrate prices increase dramatically, it will be necessary to use feeding system that satisfy requirements and promote productivity through maximizing rumen function.
  The forage and concentrate components must be combined in appropriate amounts and fortified with appropriate vitamins and minerals to provide the balanced ration. Provision of potable water to meet needs is also vital.
  Vitamins and Minerals
  Dairy cattle need proper vitamins and minerals to satisfy the many demands of production-reproduction. With the exception of salt which is often feed free-choice, vitamins and minerals are usually provided as a premix added to the basic diet. Since calves, growing and pregnant heifers, lactating cows and dry cows all have somewhat different requirements, it is best to prepare individual rations for each group. Producers mixing their own rations must be careful to insure any small quantities such as vitamin-mineral premixes that are added get blended thoroughly with the other ingredients. They should also be aware that some vitamins may deteriorate quickly after mixing so the most stable forms should be used.
  Water
  Water is a vital nutrient for all animals. Provision of ample, potable water is essential for proper operation of any dairy unit. Any water source should be free of contamination and available ad libitum.
  
  Feeding Systems
  Many options exist। In general, types of forages grown, housing system and operator preference govern the choice. Many dairy cows obtain their roughage from grazing for at least some part of the year and stored forages for the remainder. Pasture quality can vary so extra feeding may be necessary when animals graze. The most common options for feeding confined animals on dairy farms are summarized as follows:

1। Hay, Silage and Concentrate Fed Separately

• intake of each ingredient regulated to meet individual animal's requirements in tie stall units।
• best quality hay should be given to early lactation cows.
  opportunity to monitor intake and detect off feed animals quickly।
• labor intensive।
• hay can be feed in stable and silage in exercise yard to save labor but this practice sacrifices some control over individual intake। free stall housing requires three separate feeding areas.
• regulated forage intake is not possible in free-stall units
• the time that high producing cows spend in the milking parlor is now too short for ingestion of required concentrate so an alternate feeding method is necessary। Smaller or medium sized herds can restrain animals at feed mangers for extra concentrate feeding to those who need it। Larger operations may invest in and rely on computerized feeding systems for individual control। These are difficult to maintain in proper working order under the sometimes damp and often-dusty conditions found in most dairy housing units.

2. Single Forage and Concentrate Feed सेपरातेली

• single forage might be pasture, green chop, hay haylage or silage।
  minimizes need for varied harvesting and storage equipment।
• opportunity to mechanize everything।
• precise analysis of ingredients essential for accurate ration balancing।
• satisfying concentrate intake may be a problem for high producers।

3। Feeding Part of the Concentrate with Forage

• base amount of concentrate mixed with or top dressed on forage।
• top dressing may allow dominant cows in free stall unit to consume excess concentrate।
• still need method to provide extra concentrate for higher producers।

4. Total Mixed Ration

• all ingredients blended together and usually fed ad libitum।
• ration must be formulated properly and mixed thoroughly।
• can mask nutritious and economical but somewhat unpalatable ingredients।
• components altered with minimum chance of causing digestive disturbances।
• daily intake consumed in numerous small meals।
• parlor grain feeding can be eliminated।
• manger space reduced।
• accurate scales and efficient mixers essential।
• cows should be separated into groups based on nutrient requirements। Problem for small herds।
• must fine chop hay before mixing।
  

Dairy Cattle Nutrition
Calves. Newborn calves have little resistance to distress so care provided during the first few hours after birth is crucial for subsequent survival. No prenatal antibody transfer occurs in species such as cattle that have an epitheliochorial placenta. Thus, calves should ingest colostrum very soon after birth to acquire their initial immunity. Time and sanitation affect the success of antibody transfer. The potential for absorption of protein through the intestinal mucosa is high at birth and remains for up to 24 h if contamination by microorganisms is low. In contrast, if substantial numbers of bacteria are ingested before or with the first colostrum, this stimulates early gut closure and impairs subsequent absorption. Calves should be up and nursing within 0.5 h of birth and, unless the cow has been pre-milked or subjected to a short dry period, will ingest substantial immunoglobulins within the first few hours of post-natal life. The dam and calf should be separated within 24 h to reduce coliform exposure and suppress maternal instincts.
Perhaps the best way to feed newborn calves is by milking colostrum from the cow for administration by bottle, open pail, nipple pail, or one of the more complex feeding systems that are available. Any of these methods prove satisfactory provided the equipment is cleaned thoroughly between each use. Colostrum should be fed during the first three days with intake regulated to approximately 8% of body weight per day. Under feeding limits growth while overfeeding may produce gastroenteritis.
Occasionally, fresh colostrum is not available so alternate sources should be maintained. Surpluses can be stored frozen for prolonged periods or colostrum can be allowed to ferment, yielding a product that is stable for one month. Fermented (sour) colostrum should be buffered with sodium bicarbonate prior to feeding. Calves should continue to receive whole milk, milk replacer or colostrum until they reach 2 or 3 mo. Hay and calf starter should be provided during the second week with amounts gradually increased to encourage consumption. As the daily intake of solid feeds goes up, the amount of milk or replacer can be reduced so calves are weaned by 3 mo. Post-weaning rations must balance forages and concentrates to promote normal growth but to prevent obesity.
Heifers. Yearling heifers can satisfy most of their nutrient requirements from lush, actively growing pasture. Later in the season, however, when plants are mature and growth is slight, supplemental feed should be provided. If heifers are neglected at this time they may begin to lose weight and become acyclic. Provided the general nutrition program is adequate, this is perhaps the major factor contributing to delayed first calving. The Department of Animal Science at Purdue University provides a comprehensive guide for "Raising Dairy Replacement Heifers From Birth to Breeding."
Fresh Cows. Once lactation commences the nutrient demand in high producing animals increase substantially so the first two months after calving are the most difficult period for meeting requirements. For proper nutrition it is imperative that maintenance and production requirements are calculated for each individual. Healthy fresh cows should be introduced to the milking herd by 3 to 5 days postpartum. Concentrates must be increased gradually (0.5 to 0.7 kg/day) until the appropriate intake is reached. Special provisions are necessary during early lactation with all feeding systems to bring fresh cows up to full feed. Milk production rises rapidly for 6 to 8 weeks while voluntary feed intake increases gradually and usually peaks around 12 to 14 weeks. The lag in feed intake behind high milk production results in negative energy balance so maximum lactation is achieved and maintained at the expense of nutrients already stored in the body. This initial depletion creates the need for adequate replenishment of reserves in late lactation and the dry period.
After 10 or 12 weeks voluntary intake is usually adequate to fulfill requirements if a balanced and palatable ration is provided. Substantial concentrate should be fed during the first third of lactation to minimize the time when cows are losing weight and facilitate re-breeding. In the later stages of lactation more nutrients can be consumed than are required for reproduction (lactation and gestation) so positive balance ensues and weight can be regained. Some energy reduction may be necessary in late lactation to prevent obesity.
See "Guidelines for Feeding Dairy Cows" available through OMAFRA for comprehensive details on nutrition of dry and lactating cows. The Dairy Science Department at the University of Florida also has an extension publication covering "Nutrient Requirements of Dairy Cattle" available on the Internet through the Florida Agricultural Information Retrieval System (FAIRS). This latter link contains considerable information on the composition of common and not so common feedstuffs.
First lactation animals should receive an additional 20% and second lactation animals 10% over maintenance-production requirements to allow for the fact that they are still growing.
Feeding in the Early Dry Period. From termination of lactation until 2 or 3 weeks prepartum most cows can satisfy nutrient requirements from good quality roughage fortified with appropriate mineral-vitamin mixture. Thin cows should be provided with some extra energy supplement to allow recovery of body condition but gross overfeeding and associated obesity must be avoided. Small amounts of the concentrate or total-mixed-ration should be given in the last 2 or 3 weeks before freshening to allow adjustment to the postpartum ration. Comprehensive information on "Dry Cow Feeding and Management" is also available from FAIRS and the OMAFRA publication "Guidelines for Feeding Dairy Cows".
Body Condition Scoring in Dairy Herd Management. Body condition scoring of dairy cattle provides an excellent method for monitoring condition and adjusting nutrient intake to meet changing requirements throughout lactation and the dry period. OMAFRA provides an introduction into "Body Condition of Dairy Cattle" and instructions on "Using Body Condition Scoring in Dairy Herd Management" through their Internet site. A body condition scoring chart is also available from the School of Veterinary medicine at the University of Pennsylvania, with a further link to another series of instructions for implementation of a body condition scoring program in dairy herds.
Why keep dairy cows?
The main goal of any dairy herd is to produce milk as conveniently and economically as possible. Si nce the bovine gestation period is nine months long and cows require a postpartum recovery period of several months before initiating another pregnancy, it is convenient to plan around a yearly calving interval. Ideally, cows would lactate for about ten months followed by a two month dry period, as illustrated in the accompanying figure. They should be remated successfully during the first third of lactation, progress through another gestation and calve again to initiate another lactation. However, even with reasonable management, a substantial number of animals fail to conceive as anticipated so calving intervals exceed twelve months. Failure to achieve a twelve-month calving interval is not disastrous since almost all improved dairy cows produce reasonable quantities of milk for longer than ten months. Thus, although daily yields are considerably below peak amounts, they still return something over feed and maintenance costs. The actual calving interval for most herds with reasonable standards of management will usually range between 12.5 and 15 mo. Once the interval extends beyond this duration, most cows in the herd spend too much time in the lower portions of the lactation curve where the margin over feed costs is minimal or even negative. Also, in such instances, the average milk and offspring production per day of herd life is lower.
Dairy farmers seek consistently for methods to improve production efficiency (milk per unit of feed or per hectare of land cultivated) since, with high efficiency, the nutrients used for maintenance constitute a smaller proportion of the total intake. This requires close attention to the composition of diet for each production group, plus the method and frequency of feeding. Various procedures exist to enhance milk production but each must be evaluated for convenience, cost effectiveness and effect on animals and animal attendants before any are adopted.
Procedure % change in yield
Proper prestimulation, 40 to 60" 5 - 10
Stripping 6 - 9
Three times milking 12 - 20
Four times milking 15 - 25
Extended lighting 5 - 10
rbST 5 - 20
Rumensin 5 - 10

Dairy producers should establish an operational plan for each phase that, if exercised properly, provides a reasonable chance of achieving the production goals. This involves:
1। assigning specific responsibilities to individuals for each key area and insuring the people

understand their duties and that they will be held accountable for performance।

2. formulating a set of minimally acceptable standards
3. initiating a performance monitoring system
4. deciding how frequently the performance will be evaluated
5. generating a mechanism for initiating corrective action as necessary
Suggestions for minimally acceptable standards (herd goals):

Production:

• sufficient size and maturity to breed by 15 mo of age
• first calving, 24 - 25।5 mo of age
• standards for each lactation age (individual preferences)
• breeding and replacement policies (individual preferences)

Milking:

• routine (must match facility)
• drying off procedure (individual preferences)
• sampling for somatic-cell-counts (<>

Health: work with DVM with particular attention to

• sanitation
• vaccinations
• routine examinations
• udder health
• mortality, birth to first calving <>
• cow mortality < 2%
  

Reproduction:

• mean interval to first AI, <>
• estrus detection rate, 55 to 90 days, > 75% of eligible cows
• return detection rate, 15 to 30 days post mating, > 75%
• pregnancy rate to first AI, 50%
• services per pregnancy, <>
• calving interval, <>
• days open, <>

Dairy Herd Health
In the past veterinarians were like firemen, waiting for calls to come in and then rushing out to try overcoming disaster। This approach is no longer adequate whenever producers invest the considerable amounts of capital necessary to build and equip. intensive dairy facilities. Fortunately, new discoveries, particularly in the area of disease prevention, now enable the veterinarian and other specialists to work with the livestock producer to form a team that keeps animals healthy. Such programs should include, in addition to the routine immunizations and other clinical-surgical procedures, regular management consultations and provision of advice on nutrition, reproduction and udder health. To be effective, the practitioner must make regular visits and producers must be willing to compensate them for time invested rather than just on a fee-for-service basis. The actual frequency would depend on herd size, perhaps monthly as a minimum for small herds up to at least weekly for large units. Sufficient time should always be available after conclusion of the clinical activities for such things as an environmental assessment, reviewing the body condition scoring procedures, etc. and for discussing specific concerns, performance and targets, feed analysis results, and perhaps any anticipated problems or contemplated changes in management routine.

Udder Health
Mastitis, undoubtedly the most common and costly disease of dairy cows all over the world, is almost always the result of infection by pathogenic microorganisms that produce inflammation in the mammary gland. No dairy herd is ever likely to be completely free of mastitis but good operators should be able to keep its incidence down to the point where it is almost undetectable.
Milking usually occurs at the cow's regular location in tie-stall barns or in milking parlors for free-stall animals. Regardless of the type, it must provide an environment where cows can be milked quickly and comfortably under hygienic conditions. Since this is where the major dairy output is harvested, the milking area and routine are extremely important. The milking equipment functions during two or even more periods each day. This adds up to more hours each year than for all other equipment combined. Thus, a thorough understanding of proper operation, frequent maintenance and periodic updating are necessary.

1. Requirements for good udder health
   1. The designing and building of an effective milking facility (OMAFRA Factsheet).
   2. Since dairy cows are creatures of habit, a proper milking routine is essential.
   3. Monitoring udder health with the California or Wisconsin mastitis test for rapid screening of suspect quarters, by routine bulk tank and individual cow somatic cell counting (OMAFRA Factsheet) and laboratory cultures to identify the specific microorganisms involved whenever this is necessary.
   4. The elimination of existing infections through treating cows during lactation or when dry and by culling chronically infected animals.
   5. The prevention of new infections by providing an hygienic environment (OMAFRA Factsheet) ensuring that equipment functions properly, establishing a sound milking routine and with use of appropriate dry cow therapy.
   
2. Reproduction
   Successful livestock farming requires animals with ability to convert basic ingredients into marketable commodities worth more than the total cost of production. Since all consumable products, including milk, are obtained through exploitation of reproductive processes, having animals that give birth regularly is extremely important. Under intensive production conditions in industrialized countries, most dairy farmers use highly specialized breeds housed under controlled environmental conditions. With good reproductive efficiency, the biological efficiency of such monoproduct units is often high, approaching limits established by the animals' genetic potential. Maximum reproductive rates are perhaps less important in regions where animals are kept for dual and even triple purposes, but regular birth of replacements is necessary for continued production even under these conditions. Whenever specialized, intensive practices are adopted, however, satisfactory pregnancy rates must be obtained or commercial dairy farming cannot be profitable.
   A suitable goal for intensive units might be to develop breeding management systems that maximize reproductive efficiency to the extent this can be justified economically. Herd reproductive activities should be critically evaluated at frequent intervals to assess performance and prospects for improvement. In some instances the cost of additional inputs in relation to what might be achieved dictate that less than maximum efficiency must be accepted. In all cases, successful farmers are those with ability to identify problems and apply practical solutions quickly so they continuously apply methods that work well in their facility. One of the first steps in establishing a sound breeding management program is selecting challenging but achievable targets. Unfortunately, some livestock owners, particularly if they do not assume responsibility for or participate in the daily management of their reproducing animals, frequently have unrealistic expectations.
   
3. Reproductive Efficiency in Dairy Farms।
   In determining total lifetime productivity of dairy cows, total milk yield should be equated against all expenses for housing, feeding and caring for animals during growth from birth to first calving and the dry period between successive calvings, as well as during lactations. Thus, the "Precalving Interval" from birth to first parturition, as well as all the subsequent "Intercalving Intervals" between successive calvings, as shown in the accompanying figure, combined with the number of times the pregnancy cycle is successfully completed, affect lifetime reproductive performance.
   Management of calves and yearling heifers governs length of the "Precalving Interval." Similarly, nutritional status, disease prevention program and estrous detection-management procedures, plus the fertilization rate and embryo-fetal survival, influence the associated "Intercalving Intervals". Optimum reproductive efficiency involves keeping these intervals as short as is practical and economical.
   All operations with breeding livestock will have some infertility so even the most competent dairy farmers must accept that reproductive problems will occur. Even in herds with apparently similar genotypes, feeding practices and housing, variation ranges from minor and infrequent delays to situations in which almost all of the cows have greatly prolonged days open and associated "Intercalving intervals," with substantial proportions culled for infertility. Various measures of reproductive performance are available to assist competent managers recognize breeding abnormalities quickly and initiate corrective actions to treat or eliminate affected animals before the situation becomes critical. Unfortunately, many herd operators do not possess this ability so even serious management deficiencies affecting herd performance is often overlooked. The general causes of reproductive failure are summarized in the previous section on Animal Reproduction
   Poor reproductive function in dairy herds has many possible causes, some of which are listed in the accompanying figure. Areas for a more detailed investigation whenever performance is considered to be unacceptable are also suggested.
   Numerous studies indicate poor estrus (heat) detection is the most common cause of prolonged intercalving intervals in dairy cattle so herd managers must insure that animal attendants responsible for this are competent. An estrus detection efficiency of 75 % would represent outstanding performance, a standard achieved in very few herds. Even 60 % efficiency would be somewhat above average with perhaps a 45 % detection rate representing about the average for commercial dairy farms. Many herds, however, realize only 20 to 30 % efficiency, a rate that results in far to many days open. This poor detection efficiency results in greatly prolonged intercalving intervals and high involuntary culling for reproductive failure. Unfortunately, this latter situation is encountered on many dairy farms all over the world. Details on estrus and its detection are available if you wish to review them.
   Modern Dairy Breeding
   WWW Virtual Library for Dairy Production
   
   
4. 
   Body Condition Scoring of Dairy Cattle
   
   Division: Agriculture and Rural
   History: Replaces Factsheet #89-091, "Body Condition Scoring of Dairy Cattle" Written by: Jack Rodenburg - Dairy Cattle Specialist/OMAF

Introduction
Every dairy producer has cattle that are too fat or too thin for their stage of lactation. Failure to recognize these cows and take action costs dearly for disease treatments, lost milk production, and decreased fertility. This Factsheet describes how to score the body condition of cows and compare them to normal scores for various stages of lactation. The system described here was developed by E.E. Wildman, University of Vermont.
Body condition is a reflection of the body fat reserves carried by the animal. These reserves can be used by the cow in periods when she is unable to eat enough to satisfy her energy needs. In high producing cows, this normally happens during early lactation, but it may also happen when cows get sick, are fed poor quality feeds, or feed intake is restricted. After a period of weight loss, cows should be fed more than their requirements to restore normal body condition.
Cows should be scored both by looking at, and handling the backbone, loin and rump areas. Since the pin bone, hip bone, the top of the backbone, and the ends of the short ribs do not have muscle tissue covering them, any covering you see or feel is the combination of skin and fat deposits.
Assessing condition by handling is quite easy. Press the fingertips against the backbone, pin bone and hip bone. Grip the loin of the cow where the short ribs project from the backbone, just ahead of the hips, with your fingers on top of the loin, and the thumb curved around the ends of the short ribs. Fingertip pressure will provide a good indication of the amount of fat cover.
Condition scoring should be done by the person responsible for feeding the herd. To keep the scores "standardized", regularly refer back to the standards outlined in this Factsheet, and discuss condition scores with your nutrition advisors and herd veterinarian.
Cows should be scored regularly to reflect changes in fat reserves in each stage of lactation. Ideally all cows should be scored at the beginning and end of their dry period and at least 4 or 5 times during lactation. Scores should be evaluated based on stage of lactation (days in milk or days dry). In more sophisticated systems such as computerized records, the days to next calving should also be monitored. One convenient way to do this is to record condition scores on the edge of the Ontario Dairy Herd Improvement herd report after each test day. This provides a single reference to cow identification, days in milk, production level, and condition score, thereby including all the information needed to set feeding levels for individual cows. To analyze condition scores for a herd, or for a cow throughout a lactation, the individual scores can be plotted on the chart on the back page of this Factsheet. Notations such as lactation number, production level or health problems can be added above plotted points to improve interpretation of the chart.
Condition scores range from 1, a very thin cow with no fat reserves, to 5, a severely overconditioned cow. Ideal condition scores fall in the range of 3.5-4.0 at dry off and calving and 2.5-3.0, at peak lactation, with no cows changing by more than 1 condition score class over any lactation period. Refer to OMAFRA Factsheet, "Using Body Condition Scoring in Dairy Herd Management", Agdex 410/20 for more information on interpreting herd scores. Descriptions of the 5 condition score classes follow.
With practice, "hands on" scoring of the herd takes only 10-15 seconds per cow and provides a wealth of information. To monitor the results of your feeding and management program put a regular body condition scoring routine to work in your herd.
Condition Score 1
This cow is emaciated. The ends of the short ribs are sharp to the touch and together give a prominent shelf-like appearance to the loin. The individual vertebrae (spinous processes) of the backbone are prominent. The hook and pin bones are sharply defined. The thurl region and thighs are sunken and in-curving. The anal area has receded and the vulva appears prominent.

Condition Score 2
This cow is thin। The ends of the short ribs can be felt but they and the individual vertebrae are less visibly prominent. The short ribs do not form as obvious an overhang or shelf effect. The hook and pin bones are prominent but the depression of the thurl region between them is less severe. The area around the anus is less sunken and the vulva less prominent.

Condition Score 3
A cow in average body condition. The short ribs can be felt by applying slight pressure. The overhanging shelflike appearance of these bones is gone. The backbone is a rounded ridge and hook and pin bones are round and smoothed over. The anal area is filled out but there is no evidence of fat deposit.

Condition Score 4
A cow in heavy condition. The individual short ribs can be felt only when firm pressure is applied. Together they are rounded over with no shelf effect. The ridge of the backbone is flattening over the loin and rump areas and rounded over the chine. The hook bones are smoothed over and the span between the hook bones over the backbone is flat. The area around the pin bones is beginning to show patches of fat deposit.

Condition Score 5
A fat cow. The bone structure of the topline, hook and pin bones and the short ribs is not visible. Fat deposits around the tailbone and over the ribs are obvious. The thighs curve out, the brisket and flanks are heavy and the chine very round.
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Using Body Condition Scoring in Dairy Herd Management

Division: Agriculture and Rural
History: Reprinted, March 1994 of 89-088
Written by: R। Parker - Dairy Cattle Specialist/OMAF

Introduction
There are six key times during the yearly cycle when each cow should have her condition evaluated। These occur: midway through the dry period, at calving, and at approximately 45, 90, 180 and 270 days into lactation. The timing of the checks coincides with the time for making important decisions about the future feeding, breeding and health management of the cow. The following describes specific goals with regard to body condition for each stage of the lactation cycle.

Dry Period
The goal for ideal body condition score for the dry cow is 3.5. To achieve satisfactory health and performance early in the subsequent lactation condition score must fall between a minimum of 3 and a maximum of 4.
It is a well accepted fact that cattle, replenish body fat reserves more efficiently while lactating than during the dry period. Occasionally a cow must be dried off before an acceptable condition score is reached. It will pay the manager to continue to feed underconditioned dry cows for gain, to achieve a desirable body condition score. Obviously, a well managed feeding program combined with frequent observation is required to achieve condition gain without overfattening the dry cow.
Average quality, long stemmed grass hay has proven to be the ideal forage for the dry cow। Higher quality (energy and protein) forages, such as corn silage and alfalfa haylage, must be limit fed to prevent excessive condition gain. With correct forage quality and quantity, a low-energy high-fiber supplement, containing appropriate protein, mineral and vitamin levels, could be fed in controlled amounts to achieve the desired amount of gain. Removing excess fat from overconditioned cows by limiting energy intake during the dry period does not appear to seriously impair subsequent performance.

Early-Lactation
The cow should be evaluated frequently during early lactation. It is then that body condition, as it reflects energy reserve, has its greatest impact on the health, production and fertility of the dairy cow.
The cow freshening overweight, with a condition score of more than 4, is at greater risk of fat cow syndrome problems such as difficult calving, retained placenta, metritis, mastitis, displaced abomasum, ketosis and milk fever. Her immune response is usually inadequate to combat the stress of calving and appetite is less than ready to meet the demands of early lactation.
Another situation occurs when the cow starts lactation without enough energy reserve, having a condition score of less than 3.
This cow may experience fewer health problems at calving but her later productive and reproductive performance will be less than expected.
As shown in Figure 1, the average cow commonly peaks in milk production at 4 to 6 weeks into lactation. Her feed (dry matter) intake lags behind, normally peaking at about 9 to 11 weeks. This situation puts the cow in a negative energy balance for several months in early lactation. This means that feed energy intake is less than milk energy output. The cow uses available body fat (tissue energy) reserves to cover the shortfall.
The cow starting lactation in thin condition lacks adequate energy reserve and she will peak at a lower milk yield. Peak milk yield is directly related to total lactation yield with mature cows. For each additional kilogram of milk at peak there will be approximately 200 more kilograms of milk over the whole lactation. Undercondition at calving is also a cause of low milk fat test. In early lactation, a high proportion of milk butterfat precursors originate from body fat stores.
The average mature cow calving in desired body condition, with a score of 3.5 (4 maximum), and in good health, can be expected to lose between one-half and one kilogram of body tissue per day during the first 60 to 80 days in milk.
One kilogram of body tissue (mostly fat) can supply 4.92 megacalories of energy (NEL) . At 3.5% butterfat, milk contains about .69 megacalories of energy (NEL) per kilogram. Therefore, one kilogram of body tissue can provide the energy to produce 7.1 kilograms of milk. The loss of 70 kilograms of fat by the average mature cow translates into the production of nearly 500 kilograms of milk - over than supported by feed energy intake.
During the first two months in milk the average mature cow will drop between 1/2 and 1 full point in condition score, stabilizing at a score near 3 by the 10th week and beginning to regain lost condition by the 90th day. At this time, rising feed energy intake can satisfy the declining milk energy demand. This coincides with the optimum period for observation of regular estrous activity, breeding and conception.
Experience and research have shown that cows gaining weight (in positive energy balance) at the time of service have a higher conception rate than cows losing weight. A condition score between 2.5 and 3.5 would indicate adequate condition for good reproductive efficiency.
Very high producing cows may drop to a score near 2.5 before stabilizing, having lost up to 1.5 kilograms of tissue per day. They may be into the 4th month of lactation when this occurs. The expression of estrus and fertility may be suppressed in these cattle, resulting in delayed conception. Cows with good production that demonstrate no or little condition loss in early lactation are most likely very efficient feed converters. Cows that gain condition at this stage are probably poor producers.
Low energy intake in early lactation can lead to excessively high rates of fat mobilization of greater than 1.5 to 2.0 kilograms per day. This increases the risk of the accumulation of fat in the cow's liver, and can lead to ketosis, increased susceptibility to disease, a delayed return to estrus and reduced fertility.
The feeding program for cows in early lactation must therefore be carefully managed to achieve maximum dry matter intake and ration digestibility. Adequate amounts of protein are critical to stimulate intake and provide nutrients (amino acids) for milk production. The cow has limited body protein reserves to draw from.
Cows in early lactation will consume about 10% less dry matter than cows at the same level of production in mid-lactation. Therefore, providing enough protein to meet the requirement for peak milk means that the ration protein content will be in the range of 18 to 20% of the dry matter. Ideally, 40% of the protein should bypass rumen degradation and provide the amino acids that are limiting to milk production.
A compromise must be met between providing the fresh cow with large amounts of highly digestible and rapidly fermented grain starch for energy and providing adequate forage fiber to maintain rumen function and butter-fat synthesis.
The ration should be formulated to provide 72 to 75% Total Digestible Nutrients (TDN) or 1.61 to 1.67 megacalories per kilogram of Net Energy for lactation (NEL) . Total ration fiber levels should be between 19 and 21% acid detergent fiber (ADF) and between 25 and 28% neutral detergent fiber (NDF). A minimum of 21% of the total ration dry matter should come from forage NDF. Ideally some of the forage should be in the form of hay to provide stimulation for optimum rumen function.
Mineral and vitamin levels in the ration should be balanced to currently recommended standards.
Following recommended feeding management practices will also help maximize dry matter intake, eliminate the risk of cows going off-feed, and reduce the cow's dependence on body fat reserves।

These practices include:
lead feeding grain to the dry cow for 2 weeks, increasing to a maximum of 1% of body weight at calving,
challenge feeding grain and protein supplement to the fresh cow, increasing gradually to the recommended maximum advised by ration formulation, by three weeks into lactation,
feeding concentrates in meals of less than 4 kilograms, more frequently (i.e. 4 times) per day,
feeding the highest quality forages available,
following the feeding sequence of forage before grain and grain before protein supplement, ideally with some time delay between, for optimum ration digestibility,
feeding more often when rapid feed spoilage is a problem,
keeping mangers and water bowls clean and free of hazards,
chopping forages to maintain adequate particle size (greater than 1 cm) and processing concentrates as coarsely in texture as possible to stimulate rumen function and feed consumption,
using molasses to improve the intake of unpalatable or dusty feeds,
using buffers, such as sodium bicarbonate at .75 to 1.0% of total dry matter intake, to improve the digestibility and intake of high concentrate rations,
adding .5 to .75 kilograms/day of rumen protected fat to the cow's ration to increase the energy density while reducing the need to rely on starch as the primary source of dietary energy. When adding fat to the ration, calcium and magnesium levels need to be raised to 1.0% and .3%, respectively, and attention must be given to providing adequate bypass protein and functional fiber in the ration.
Adding 6 to 12 grams of niacin to the ration during the lead feeding and throughout the early lactation period will help high producing cows that freshen in desired or heavy body condition to use dietary fat and body fat stores more efficiently।

Mid-Lactation
At about 180 days in milk, a body condition appraisal should confirm that cows are replenishing body fat reserves that were lost in early lactation। By this stage of lactation, condition scores should be approaching 3 for the highest producing cows in the herd and between 3 and 3.5 for the average producing cows. Below average cows may have already exceeded a condition score of 3.5 and will need to be fed carefully to prevent fattening. All cows being rebred should be confirmed pregnant by mid-lactation.

Late-Lactation
The condition score check done at approximately 270 days in lactation should show the average cow approaching a score of 3.5. During this period, low producing cows tend to become over-conditioned, showing scores at or above 4. This occurs more often where large amounts of corn silage are fed and where attention is not paid to limiting access to concentrates. Cattle fed grain in milking parlors should be allowed sufficient time to clean their share, leaving none behind for the next cow that occupies the stall. In tie-stall barns, manger dividers may be needed to prevent cows from stealing unneeded grain from immediate neighbors.
Overconditioning also happens in free-stall herds fed total mixed rations where the cattle are not adequately grouped according to production. At least 4 and perhaps 5 lactation groups; early, mid, late, first-calf, and dry may be needed to prevent overconditioning.
In herds where extended calving intervals prolong the period of low production and/or the dry period, many cows will become overfat. In this situation the breeding management needs to improve.
Very high producing and persistent cows, like first-calf heifers, with normal calving intervals, may be difficult to get to the goal of 3।5 in condition score while still milking. With these cows, it may be necessary to continue to feed for gain during the dry period to frilly recharge their energy reserves.

First-Lactation Heifers
The ideal condition score for the heifer calving for the first time is about 3.0. Heifers freshening with condition scores in excess of 3.5 have experienced more calving difficulty.
First-calf heifers need to be managed somewhat differently from their older herdmates. They will calve with 100 to 150 kilograms less body weight than the older cows in the herd. Their daily concentrate amount must be adjusted accordingly to maintain correct forage-to-concentrate ratios to prevent problems related to digestive system malfunction.
The lactation curve of a first calver does not show the early high peak that higher lactation number cows demonstrate. Therefore, the negative energy balance occurring in early lactation will not be as demanding on body fat reserves as it can be for older cows.
First-calf heifers do show greater persistency of lactation than older herdmates. The first calver will show an average drop of 4% per month in mid-lactation compared to 8% in older cows. In late-lactation, the first calver will fall in milk at 6 to 8% monthly while the higher lactation number cows are declining at 10 to 14%. This greater persistency means that the heifer cannot route as high a proportion of energy intake as can her older herdmates toward the replenishment of body fat stores.
First and second-calf heifers also have a major additional need for energy - for growth - throughout mid-and late-lactation and the dry period. These cattle must gain 50 to 75 kilograms during each of the first two lactations to reach mature body weights.
To ensure that the additional nutrients needed for growth are provided, the standard recommendation has been to feed more concentrates to these cattle. During the mid-and late-lactation phase the first calver should get 10% and the second calver 5% more concentrates than required for milk and body condition gain.
Failure to provide these extra nutrients may be the cause of heifer "burn-out". Today's genetically superior cattle can produce large volumes of milk, even during their first lactation. If special care is not provided, they will begin the second lactation stunted and/or lacking adequate energy reserve.
With the mature lactation curve, typical of second lactations, adequate tissue energy reserves are critical to achieving desirable peak milk yields as well as satisfactory butterfat synthesis. Body size is a major factor influencing dry matter intake. Lack of sufficient growth will limit the improvement in feed intake needed to support higher milk yields.
As a result of inadequate management the genetically superior heifer could demonstrate poor second lactation performance or burn-out, and may be wrongly culled.
Correct management of energy balance throughout the lactation and reproduction cycles of the dairy cow can significantly improve her capacity to generate profit.
OMAF Factsheet Body Condition Scoring Of Dairy Cattle, Agdex 414/10 provides illustrations of specific conditions scores.
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