Heifer Nutrition and Management
Mary Beth de Ondarza, Ph.D., Technical Services Nutritionist
F.A.R.M.E. Institute, Homer, NY
How are the heifers growing on your farm or the farms you visit? Do we really know their actual growth rates or is the answer, "Oh, they look great out there on the hillside, don't they?", a good enough answer for us. Our challenge is to monitor growth rates in heifers, feed rations balanced for optimal growth of muscle and bone, and then find out how great (in actual measured amounts) those heifers are growing.
The Newborn Calf:
The newborn calf must receive an adequate amount of high-quality colostrum as soon as possible after birth. Colostrum contains about 20% protein (rather than 3.2% in normal milk). Most of this protein is in the form of immunoglobulins (antibodies) which the calf needs to fight off disease. Since calves cannot make these immunoglobulins themselves during their first few weeks, they must ingest them from colostrum. However, the ability of the intestine to absorb these immunoglobulins diminishes with time after birth to the point where at 24 to 30 hours they can no longer be absorbed. Studies have shown that the sooner the calf ingests colostrum, the higher the likelihood that she will survive the first few weeks of life. Immunoglobulins which are absorbed from colostrum will help the calf to fight off respiratory and intestinal bacteria for 2-6 months.
It is generally recommended that the calf should receive colostrum at an amount equal to 5-10% of body weight within 4 hours of birth. Colostrum should be fed for a total of three days after birth at 6% of body weight. Unfortunately, the level of immunoglobulins varies in the colostrum of different cows. 50 mg total immunoglobulins/ml is considered good but the range is from 15 to 120 mg/ml. First-calf heifers will produce colostrum with a lower percentage of immunoglobulins, possibly because they have not been exposed to as many diseases as older cows. The immunoglobulin concentration will also decline with the number of milkings. If the cow's diet is deficient in protein prior to calving, she may produce colostrum with less immunoglobulins. Colostrum quality can be evaluated using a colostrometer which relates immunoglobulin concentration to the specific gravity of the colostrum. One may want to allocate colostrum to calves according to its quality by freezing the better colostrum. Supplementation of poor quality colostrum using colostral replacers may also be effective. Even though after 24 hours, the immunoglobulins are essentially not absorbed from the intestine, they are still important for the next 48 hours to guard against intestinal diseases. The higher protein and fat in the colostrum is also useful during this period of stress for the calf.
Phase I - The First Two Months:
Calves should be fed milk, milk replacer, or fermented colostrum during the first 6-8 weeks of life. Whole milk should be fed at 8-12% of body weight, preferably split between two feedings. The amount of milk replacer fed may vary depending on the manufacturer. Most milk replacers are recommended to be fed at 8 oz./2 qt. warm water twice per day or at 16 oz./2 qt. warm water once per day (with supplemental water available). Fermented colostrum also can be fed after diluting it with water. It has been estimated that 6 lb. of fermented colostrum and 2 lb. of water is equal to 8 lb. of whole milk.
Every effort must be made to stimulate the calf's appetite for dry feed. Calf starter, or preferably calf starter with a coccidiostat, should be offered starting a few days after birth. Calves should be consuming at least 1.5 lbs. of calf starter per day before weaning. Rumen development is dependent on the production of volatile fatty acids, particularly butyrate and propionate, making grain consumption very important. At six weeks of age (or weaning), high-quality grassy hay should be offered to stimulate cud-chewing and increase contractions in the rumen. Poor-quality hays as well as all types of silages are not recommended for calves less than two months because they contain too much bulk for the calf's small rumen and are not utilized well. Urea should not be fed at this time because the rumen is not fully functioning at this time and the urea cannot be used to form microbial protein.
Scours or diarrhea often cause dehydration and even death in young calves. An electrolyte solution can help to restore body fluids and minerals. These solutions should be used to supplement milk, not replace it. Feed the recommended amount of milk at normal feeding times. Then, feed the supplemental electrolyte solution halfway between milk feedings. Tube feed calves only when they refuse to suckle. Commercial electrolyte solutions are available or they can be homemade. The following are two different suggested mixtures:
1 can beef consomme OR 1 egg
2 teaspoons baking soda
1 pack Sure Jell
2 teaspoons Lite salt
(make up to 2 quarts with water)
Calves infected with coccidia get less nutrients out of the food they eat and have lower growth rates. Calves don't develop any significant immunity to coccidia until after 100-120 days and after that, they can still potentially be affected up to two years of age. Calves stressed by crowding or poor environmental conditions will generally show more signs of infection. Deccox (0.23 mg/lb BW/day) and Bovatec (0.45/lb BW/day) can both be used to control coccidiosis.
After the First Two Months:
It has been my observation that many farmers pay close attention to their calves less than two months of age, but after that, the calves get thrown into a pen somewhere and are forgotten. DHI data indicates that the average age of first calving and the average post-calving body weight of heifers in New York is 28 months and 1140 pounds, respectively. A number of university studies conducted during the past few years have concentrated on measuring and improving heifer growth and found it to have a significant economic impact on the total farm business.
The Use of an Ionophor (Bovatec or Monensin) as a Growth Promotant:
Ionophors inhibit the growth of a certain type of rumen microbe, called the Gram-positive bacteria. Ionophors change the ability of the bacteria to transport certain ions, primarily sodium, potassium and hydrogen, resulting in growth inhibition of the bacteria. Included in the Gram-positive category are: those bacteria that produce a lot of lactic acid and drive down rumen pH creating acidosis, those bacteria that digest a large amount of dietary protein, and those bacteria that produce hydrogen ions which must be converted to methane and wasted by the animal.
Thus, feeding ionophors results in higher growth rates due to increased microbial protein synthesis, reduced wastage of dietary protein, and increased feed digestibility. Energy is diverted from methane production to propionate production leading to more energy retention by the animal. For these reasons as well as the role of Bovatec and Monensin as coccidiostats, they are an integral part of a good heifer raising program.
Phase II - Weaning to Breeding:
At this point, it is important that the heifer not be grouped by age, but instead, by weight. For this reason, heifer weight and body condition score need to be monitored. It is not enough to observe them from the alley outside the pens. Tape weights have been shown to be reasonably accurate for younger calves. A body condition score of 3.0 is ideal. We want calves to be gaining muscle and bone, not fat.
High-quality second or third cutting mixed hay which is fine-stemmed and mold-free to stimulate appetite should be fed free-choice. Silages and pasture have generally not been recommended for calves less than 400 pounds because it has been thought that the calf cannot consume enough dry matter from the wet forage. However, in a recent study at Michigan State (Arndt and Skidmore, 1993), dairy steers were fed either alfalfa hay or silage and no differences in dry matter intake were observed. All steers gained an average of 2 pounds per day. It was concluded that management and forage quality are probably more important in maximizing forage intake than the moisture content of the forage. Feeding silages requires a higher level of management to stimulate intake than does feeding hay.
During Phase II of heifer growth, heifers are still not capable of consuming and fermenting large quantities of fiber and their protein and energy requirements for growth are high. University and feed company research have shown improved growth rates when Phase II heifers were provided diets balanced for energy and protein. Achievement of average daily gains of 2.0-2.2 lbs/day (large breeds) without excessive body conditioning during Phase II, has been shown to result in larger framed, higher producing heifers calving at an earlier age.
The manufacture of protein for muscle and bone development requires a supply of a variety of amino acids. Proteins are rated for protein quality based upon the profile of amino acids that they contain versus the profile of amino acids required by the animal. If just one amino acid is deficient, it will limit protein production by the animal. Heifers will respond with muscle growth when they are fed a blend of high-quality protein sources.
Puberty is associated with the weight of the heifer rather than her age. It usually occurs between 550 and 650 pounds (Van Amburgh et al., 1993). The development of the udder occurs in two stages, pre- and post-pubertal. The growth rate of the mammary system before puberty is allometric, meaning that it is much faster than the growth rate of the body. The size of the fat pad and the ducts going into the fat pad increase at this time. Work at Michigan State indicated that the rate of mammary growth before puberty was 3.5 times the rate of body growth. These workers also found that excessive energy intake during the pre-pubertal period had a negative effect on the mammary system and decreased subsequent milk production. However, recent work at Cornell (Van Amburgh et al., 1994) has shown that it is the balance of protein and energy absorbed from the intestine which is important rather than simply the amount of energy metabolized. Heifers were fed diets balanced for the carbohydrate and protein fractions and groups of animals gained 1.6, 1.9, or 2.1 lbs/day during the pre-pubertal period with age of calving at 24, 22, and 21 months, respectively. Mammary development as evidenced by first lactation milk yield was not compromised by accelerated growth during the pre-pubertal period.
Phase III - 600 - 1350 pounds:
During Phase III of heifer growth (breeding to three weeks before calving), heifers are capable of consuming larger quantities of forage which they ferment to provide a large proportion of their energy and protein needs. It is desirable to maintain a high growth rate (1.7 - 1.9 lbs gain/day, large breeds) without excessive body conditioning during this time.
Since the Phase III heifer is consuming a greater quantity of forages than the younger heifer, it is necessary to provide more rumen degradable proteins to be converted to rumen microbial protein and to decrease the proportion of undegradable protein in the ration. This strategy ensures greatest feed efficiency.
If refusals from the lactating cows are being fed to the heifers, try to take a stab at their nutrient content and supplement accordingly. Remember that the nutrient analysis of the refusals will not be the same as that offered because cows tend to leave the fibrous components (i.e. corn cobs) of the ration and pick out the grain.
Remember also that environmental conditions effect maintenance requirements. Since this requirement is variable and difficult to predict, it is important to watch body condition and adjust the ration accordingly, especially at times of heat or cold stress.
The Pre-Fresh Heifer:
It is recommended that heifers be fed a pre-fresh diet 3-4 weeks prior to calving. Probably this diet is even more important for the heifer than for the older cow. Most first-calf heifers have smaller rumens and therefore, consume less feed. They also tend to be less aggressive at the bunk. A more nutrient-dense ration containing some long hay and the same silages fed to the lactating cows should help to adjust the rumen and help the heifer to be at maximum dry matter intake soon after calving.
Arndt, Jr. F.M. and A.L. Skidmore. 1993. Effect of alfalfa hay and alfalfa silage based diets on average daily gain and dry matter intake on male Holstein calves after weaning. J. Dairy Sci. 76:275 (Suppl 1).
Sejrsen, K., J.T. Huber, H.A. Tucker, and R.M. Akers. 1982. Influence of nutrition on mammary development in pre- and post pubertal heifers. J. Dairy Sci. 65:793.
Van Amburgh, M., D. Galton, D. Fox, and C. Holtz. 1993. Predicting the most profitable heifer feeding program. Northeast Winter Dairy Management Schools - Extension Recommends, Cornell University. p. West-M-1.
Van Amburgh, M.E., D.M. Galton, D.G. Fox, D.E. Bauman, L.E. Chase, H.N. Erb, and R.W. Everett. 1994. Effect of pre-pubertal growth rate in Holstein heifers on first lactation milk yield. J. Dairy Sci. 77:712 (Suppl 1).