MANAGEMENT COMPONENTS

SECTION 2. HEIFER CARE FROM WEANING TO CALVING

Weaning involves the transition from a milk replacer or milk-based diet to a forage and/or concentrate diet. Calves should be offered a starter ration in addition to milk or milk replacer, when they are approximately 1 week old. Calves should be consuming 1 to

1½ pounds of starter ration per day at weaning time, usually when they are 6 to 12 weeks old. The calf starter pro-motes rumen development and provides nutrients to support growth and health.

Generally, calves should be weaned gradually. Often, it is preferable to wait a few days after weaning before moving the newly weaned calf from the calf rearing facility to a group pen of similarly aged calves.

Birth and weaning are the two most stressful periods in a calf's life. Management errors can often lead to increased health problems and/or reduced growth. Successful weaning programs minimize stress from crowding, competition with older calves, and weather.

The period between weaning and breeding is not a time of intensive management activity. Calves should be housed to minimize weather stress and allowed free choice to water. Rations should be balanced and fed so heifers reach a breeding weight of 750 to 800 pounds by 13 to 15 months of age, with a body condition score between 3.25 and 3.5 on a 5-point scale where 1 is emaciated and 5 is obese. (All body weight and rate of gain goals are for Holsteins and should be adjusted for other breeds.)

Heifers are usually bred artificially in corrals with locking stanchions, or in a restraining chute. Various estrous synchronization methods may be used to improve heat (estrus) detection.

Replacement heifers should be fed high forage rations between breeding and calving (approximately 15 to 24 months of age). Housing should provide shelter from the elements and enough manger space for all heifers to eat simultaneously. A pre-calving body weight of 1,350 to 1,450 pounds, with a body condition score of 3.25 to 3.75 is desirable for Holstein heifers.

Housing Newly Weaned Calves

Calves should be weaned into small groups of animals, usually 5 to 12 calves per group. Newly weaned calves should not be mingled with older calves that are already established in the corrals. Pen size is recommended to be a minimum of 200 square feet per

calf in open corrals, with at least 18 inches of feed bunk space per animal. Clean and fresh water should be provided free choice. As little as 35 square feet per calf are provided in some functional intensive housing designs. There should be enough calf pens to hold about one month's production of weaned calves so each calf spends about a month in a small group.

An alternative system is to wean calves into "superhutches," which are portable pens providing a feeder, water trough, and shelter for 5 to 12 calves. Superhutches should provide 25 to 30 square feet per calf. They can be moved in a field or pasture as needed to provide calves with a clean surface.

All calf pens should be well-drained. While wet corrals cannot be avoided in rainy weather, they should drain water so mud is minimal. Accumulated manure should be removed frequently.

Pens for newly weaned calves should have 20 square feet of shade per animal. Shades should be oriented north to south and be high enough to allow sun to dry the area under them. Shades are often built on mounds to allow calves a dry place to rest in rainy weather. In the winter, dry bedding should be provided under dry shades. In some climates, permanent or temporary windbreaks may be desirable in winter (e.g., a pile of straw bales on the windward side of the pen).

Newly weaned calves often have difficulty reaching and consuming feed that is placed in front of stanchions. Calves may not be familiar with eating from ground level bunks since they are often fed starter rations from raised buckets. They are also not accustomed to operating self-locking stanchions. A feed trough may need to be placed inside the pen until all calves become familiar eating at ground level.

Self-feeding grain tanks are not recommended for newly weaned calves. Soiled and wet grain may accumulate in the trough which can promote mold growth. If self-feeders are used, the feed in the troughs must be kept fresh to maintain adequate feed intake.

Continuous access to clean, fresh water is essential for optimum health, feed consumption, and growth rates. Each pen should have a water trough that is small enough to allow water to remain fresh, but large enough so all calves have access to water when they require it. A trough that is at least 6 feet long and 4 to 5 inches deep is ideal for groups of up to 15 calves. The water trough should be located for easy calf access in a shady area and should have a drain plug for easy cleaning. It should be located so that overflow and drained water will not create a muddy or slippery area. This is usually accomplished by placing it on or near the concrete apron behind the stanchions. Water troughs should be cleaned regularly to remove fecal contamination, feed, algae, and other foreign matter.

Fences and gates should be secure. Loose rods, cables, and wires should be repaired promptly to avoid injury to calves and handlers. Gates should be arranged so calves can be sorted and easily moved from pen to pen.

Housing Heifers from the Second Month After Weaning to Breeding

Group size may be increased as calves become older. If heifers are weaned at 60 days of age, heifers from 90 to 150 days may be housed in groups of 30. Groups of 60 to 100 may be suitable from 150 days to breeding. After 150 days, heifers may be placed on pasture or housed in groups of up to 200. Heifers should be sorted so that groups are uniform, with individual calves having no more than an approximate 10 percent weight variation from the mean of the group.

Once calves learn to eat through stanchions, stanchion line feeding can be used. Self-feeding tanks may also be used, provided they are monitored frequently and cleaned as needed. Pen area and manger length requirements are outlined in Table 1.

Pens should be graded to prevent mud accumulation. Shade is recommended, especially in hot climates. Water troughs should be small enough to allow water to remain fresh but large enough to allow all animals free access to water.

Rations between weaning and first calving should meet the National Research Council's Nutrient Requirement for Dairy Cattle (NRC, 1989). Growth rates exceeding those in the NRC are attainable, although, if they cause fattening, they are not desirable.

Table 1. Space Requirements for Growing Heifers in Semi-Arid Climates

Age (months)	Stanchions/10 ft.	Shade ft2/head	Corral ft2/head
1.5 to 5	7	20	200
6 to 16	6	30	300
17 to 26	5	30	400

Source: Wiersma, F., W.T. Welchert and D.V. Armstrong. 1991. "Planning Ahead." The Dairyman 72:28.

Newly Weaned Calf Nutrition

Milk feeding is usually discontinued 4 to 5 days before the calf is placed in a group pen, but only if the calf is eating at least 1 to 1 ½ pounds of calf starter daily. Some dairy producers reduce milk feeding to once a day during the second month to encourage calf starter consumption. The presence of fresh clean water increases dry feed intake.

Newly weaned calves should be fed free-choice the same starter grain mix introduced before weaning. Rate of gain should be 1.5 to 1.8 pounds per day, with a maximum of 2.3 to prevent fattening. Calves may be fed at least 5 pounds of starter grain per day and have free-choice access to hay. Calf starter grain mix should contain 16 to 18 percent crude protein. Cottonseed products should be limited in the ration, since cottonseed contains gossypol, which is toxic to calves. Alfalfa hay for newly weaned calves should be soft stemmed, leafy, green, and palatable, with a crude protein of at least 20 percent and a total digestible nutrient (TDN) content of at least 54 percent on a 90 percent dry matter basis.

Feeding Programs from 30 Days Post Weaning to Breeding

Calves are usually fed hay and starter grain mix for about one month after weaning. Then calves may be fed a grower mixture (approximately 14 percent crude protein concentrate) with forages. After 120 days of age, calves may be fed a total mixed ration (TMR), although some dairy producers successfully feed a TMR much earlier.

Requirements for growth after 180 days of age can be met with high quality forages and higher fiber by-product feed stuffs. Some grain supple-mentation may be necessary to attain growth rates of 1.5 to 1.8 pounds per day or more. Since feed intake varies with ingredient quality and weather, growth rate and body condition of heifers should be monitored and ration adjustments made as necessary. Salt or trace mineralized salt should be available in block or loose form if it is not included in the ration.

Breeding to Calving Nutrition

Pregnant heifers are usually fed high forage diets until a few weeks prior to calving. The goal is for Holstein heifers to calve at 24 months of age with a precalving body weight of 1,350 to 1,450 pounds, body condition of 3.25 to 3.75 on a scale of 1 to 5, and wither height of at least 52 inches. Salt may be withheld from close-up, periparturient heifers in herds where udder edema is a problem.

Health and well-being of heifers are largely determined by the adequacy of the facilities and management. When adequate facilities management cannot be provided, heifer calves should be raised off the dairy in specialized facilities. This is acceptable as long as transportation practices are safe and humane.

Many calf disease problems have their origin in housing, management, feeding deficiencies, and weather stress. Severe weather can predispose calves to sickness even with the best heifer raising programs.

Age of Weaning

Calves may be weaned from milk or milk replacer as early as 30 days of age and removed from hutches to group pens as early as 40 days. However, milk usually is discontinued at 45 to 55 days and calves removed from hutches at 55 to 65 days. While some producers leave calves in hutches and feed milk or milk replacer for up to 90 days, this can be counter-productive as the heavier calves require additional feed and water to allow for optimal growth. Larger calves also produce more feces and urine, thus requiring supplemental bedding and waste removal to keep the environment clean and dry.

Since the birth rate of heifer calves is not constant, weaning age can vary. For example, if a large number of heifers are born and all hutches are full, some calves may require early weaning. If weaning pens are full, weaning may be delayed. This is acceptable if feeding programs are adjusted and housing facilities are kept clean and dry.

Breeding

Heifers may be bred artificially using the same techniques used for milking cows. They may be placed daily in stanchions for estrus (heat) detection with the aid of tail chalk or heatmount detectors. Heifers on pasture or in pens without stanchions may be heat detected by observation and then bred in a restraining chute. Heat detection may be facilitated by synchronizing the estrous cycle of heifers. This is accomplished with progesterone implants and/or prostaglandin injections.

After artificial insemination, heifers are often placed in groups with breeding age bulls to allow natural service of those animals that did not conceive with artificial insemination. Heifers not conceiving should be palpated rectally to determine reproductive tract status abnormalities. Low birth weight or calving ease sires should be used to minimize calving difficulties.

Identification and Records

Heifers usually are identified with plastic ear tags shortly after birth. They may be given numbers in a separate series from that used in the milking herd or receive a number that will follow them until they leave the herd. They are often retagged at the time of first calving with their permanent cow identification number.

It is useful to write the calf's birth date on the tag to allow easy evaluation of growth rate relative to herdmates. Heifers also receive a metal brucellosis identification tag at the time of vaccination by a veterinarian. This provides a unique number that is often used for testing and regulatory purposes.

Extensive records are not usually kept on heifers but are encouraged. Births and deaths should be recorded. Most dairies with computer records initiate animal records at birth. Records of treatment of sick animals should be kept to avoid residues if an animal is slaughtered for food purposes. Breeding dates, sire identification, and pregnancy diagnosis results are usually recorded in computer records. Additional records that may be helpful are body condition scores, average daily weight gain, mastitis, or other health problems.

Vaccination Programs

Vaccinations recommended for heifer calves include Infectious Bovine Rhinotracheitis (IBR), Bovine Respiratory Syncytial Virus (BRSV), and Bovine Viral Diarrhea (BVD) at 4 to 6 months of age and again before breeding. They should be vaccinated with Leptospirosis bacterin at those times and again at pregnancy diagnosis. Clostridial vaccination may be beneficial in certain regions. Pregnant heifers may be vaccinated with J-5 E. coli bacterin before and at calving to help prevent coliform mastitis during lactation.

Heifer calves should be vaccinated for brucellosis between 4 and 8 months of age by a veterinarian. At this time they are tattooed in the right ear and a permanent metal brucellosis vaccination identification or USDA series number tag is placed in the right ear.

Parasite and Fly Control

Flies breed readily in a moist, warm environment. Wet, organic bedding and accumulated manure create an ideal environment for fly breeding. Flies can be a significant stress on young calves. Control should be based on destruction of fly larva habitat by moving calf hutches frequently and removing accumulated bedding and manure.

Fly larvae and pupae also live in corral manure, especially in relatively undisturbed areas such as weedy fence lines, around water troughs, and behind stanchions. Some species of flies breed in piles of straw, hay, and other organic debris. Keeping a farm neat and clean and removing manure from under fences and behind stanchions can help reduce fly numbers. Insecticide dust bags in corrals help keep adult flies off calves. Spraying corrals and haystacks with approved insecticides can temporarily reduce the number of adult flies. Chemical control of flies should not be the sole method for fly control. All labels should be reviewed before chemicals are used because there are various milk and meat withdrawal periods.

Heifers kept on pasture should be dewormed on a schedule that is designed for local climatic conditions. Purchased heifers of unknown origin should be dewormed at least once prior to calving. Heifers housed only in drylots do not require deworming.

Feed Additives

Infection with coccidian parasites can cause no noticeable signs of illness to severe symptoms of profuse diarrhea. A coccidiostat (Decoquinate, Lasalocid, or Monensin) should be fed as a supplement from weaning to 180 days of age and may be fed prior to weaning. Ionophores (Monensin or Lasalocid) also act as coccidiostats and may be fed to increase feed efficiency and weight gain. These products should only be used according to manufacturer's directions or under supervision of a veterinarian.

Oxytetracycline, chlortetracycline, or chlortetracycline/sulfamethazine feed additives may be used to help prevent respiratory disease. These products are useful when calves are subjected to adverse weather and stress, before and during stressful management procedures such as vaccination, weaning, or dehorning, and to help contain out-breaks of respiratory disease. Observe all withdrawal times to avoid residues in meat of slaughtered calves.

Treatment Facilities

A hospital pen is recommended for the dairy to isolate and treat sick calves. Locking stanchions make observation and treatment easier. All calves should be observed daily and sick or injured calves treated promptly.

Following weaning, heifers may be placed on pasture in groups sorted by similar weights.