Calf nutrition key to replacement heifer success

 By Michael Cox

‘A good start is half the battle,’ is a saying that certainly rings true for early calf nutrition. As replacement heifer calves are a limited resource of future high genetic-merit cows in the milking string, producers should strive to provide good quality nutrition to get calves off to the best possible start in life.

Colostrum
Excellent calf nutrition begins first and foremost with colostrum. High quality ‘liquid gold’ colostrum is crucial for passive immunity transfer of immunoglobins from dam to calf. Research studies from around the world regularly state that 50 per-cent of calf mortality in year one occurs during the first six weeks after birth. Colostrum is key to reducing future illness and mortality in youngstock. An NAHMS 2007 study shows less than 15 per-cent of dairy farms test for colostrum quality. So how do we know if our colostrum is up to scratch? A Brix refractometer or a digital refractometer is a useful tool to help identify good and poor-quality colostrum. Antibody IgG levels of 50mg per mL or more is considered good quality. On a Brix refractometer, this colostrum will give a reading of 22 percent or greater. An alternative method for testing colostrum quality and intake is to perform a total protein blood count on calves between one and four days old. 5.2g per dL or greater of total blood protein indicates first-rate passive transfer of immunoglobins.
In Ireland, dairymen have seen widespread improvements in calf performance by implementing a ‘Colostrum 1,2,3 Program.’ Colostrum 1,2,3 is a nationally publicized program that involves three steps;
Step 1 – 1st milk only. Milk from the first milking only is to be used as colostrum. Milk from subsequent milkings will contain massively reduced levels of antibodies and is not suitable as a first feed for newborn calves.  
Step 2 – Two hours. Time is of the essence when feeding newborn calves colostrum. The gut wall of the calf has a time-limited window to absorb immunoglobins, after which it seals up and become impermeable to the beneficial IgGs. Colostrum should be fed to calves via stomach tube within the first two hours after birth.
Step 3 – Three liters. Depending on the breed type/size of the calf, a minimum of three liters of colostrum should be fed.
Ideally, calves should also be ‘snatched’ or removed from the dam as soon as possible after birth to reduce disease risk. Newborn calves in the maternity/freshening pen are particularly at risk to picking up Johnes disease, as mature carrier cows will often shed this disease during periods of stress, i.e. calving.

Whole milk vs Milk Replacer
After sufficient colostrum has been taken care of, the calf can now move on to a whole milk or milk replacer diet. Although whole milk on a dry matter basis often contains higher protein (24%-27%) and higher fat (28%-36%) than milk replacer powder, many producers prefer the consistency, minimal disease risk and economic benefits (depending on mailbox milk price) that milk replacer provides. Heifer calves should be offered at least 15% of body weight in milk daily, typically 4-6 liters or more during the first few days of life. If milk replacer is used, producers should check the source of fat on the ingredients list. Animal based fats will offer better digestion than plant based fats and can reduce levels of nutritional scours.
There is currently some debate as to whether twice-a-day ‘accelerated’ feeding programs are better than once-a-day feeding. Although accelerated twice-a-day programs are linked to larger-framed mature cattle and increased milk production in later life, there are some questions as to the net effect on farm profitability. Once-a-day feeding is widespread in New Zealand, where calves are typically grouped in mobs of fifteen to fifty calves, depending on age. The main benefits of once-a-day feeding include reduced labor and earlier weaning ages. Calves can be weaned earlier as the once-a-day system promotes faster and greater intakes of starter grain. Adequate growth rates of 1.5lbs per day have been reported on once-a-day systems by University of Minnesota Extension.
During cold Spring weather, some producers are seeing benefits of feeding during the early morning hours from 1am-3am, to help calves get through the coldest part of the day and minimize environmental stress.

Consistency
Regardless of the feeding system, consistency is key in early calf nutrition. For producers using whole milk, one way to increase consistency is to pasteurize the milk before feeding. Bacteria load in whole raw milk can vary greatly day-to-day and pasteurization will help reduce bacteria levels to a safer, lower level. Two types of pasteurization are available to dairymen, ‘batch’ and ‘HTST’ pasteurization. Batch pasteurizing involves heating a tank of milk to 63*C for thirty minutes. HTST – High Temperature Short Time pasteurizing rapidly heats milk to 72*C for fifteen seconds, before the milk is quickly cooled again. Milk must be cooled after pasteurization as a small number of bacteria will be present and multiply faster in warmer milk. Reports from Penn State University highlight the benefits of feeding pasteurized milk including, “improved weight gain, improved calf health, lower disease transmission and utilizing ‘waste-milk’ effectively.”
Calves should be fed at the same time of day and in the same order. Ideally a dedicated calf rearer or team will take care of calf rearing duties. This will promote greater ‘buy-in’ and responsibility for high-quality work. It will also minimize animal health issues as milking staff or other farm workers will not be in contact with young calves.
Adequate fresh water must be available to calves at all times and starter grain should be introduced after one week of age. Weaning should only be considered once calves are consistently eating 3-4lbs of grain daily. A gradual weaning process over several days using reduced and diluted milk levels will provide a seamless transition from liquid to solid food for young calves.
While calf-rearing systems are unique to every farm, the key components of good quality colostrum, consistency of feeding and a gradual weaning process must be built into every plan. With mailbox milk price looking challenging over the coming months, producers should still maintain good calf-rearing protocols and avoid the short-term temptation to cut costs in calf-rearing.

Michael Cox is a freelance writer for American Dairymen. His background is in Animal Science, where he graduated from University College Dublin Ireland with a First Class Honors degree in 2016. He is currently involved with a dairy business in Missouri, managing a 750 cow grass-based grazing farm and am also a research scholar with University of Missouri- Columbia.