Dairy farmers are aware of the importance of colostrum and the impact it can have on getting calves off on the right foot from the start. On many operations, a full feeding of colostrum is followed by transition milk or a switch to a quality milk replacer. That switch begins the period of most potential for calf growth.
“Feeding rates of dry matter, and more specifically protein and energy, are directly related to the amount and composition of gain for preweaning calves,” shared Miner Institute’s Sarah Morrison.
In a recent Miner Institute Farm Report, Morrison summarized a research study from the Journal of Dairy Science that looked at the energy requirements for growth in calves.
Calves were provided one of three feeding levels of milk replacer feeding rate. A 24.8% crude protein and 18.9% fat milk replacer was offered at 1.25% of body weight, 1.75% of body weight, or 2.25% of body weight. As-fed amounts were modified weekly as the calves grew, and importantly, no grain was offered during the study.
After 35 days on the program, calves were evaluated for weight gain and gain-to-feed ratios were calculated.
The researchers from the University of Illinois, Cornell, and Michigan State found that the common feeding rate of 1.25% of body weight was restrictive to calf growth in comparison to the two higher rates.
“Feeding calves on a scheme in which they would consume milk replacer with adequate protein at or more than 1.75% of their body weight increases the amount of lean tissue and fat deposition and the efficiency of gain,” the researchers concluded in their Journal of Dairy Science article.
Calves fed at 1.75% of body weight had a final body weight of 155.32 pounds (70.6 kilograms), an average daily gain of 1.54 pounds (0.70 kilograms), and a gain to feed ratio of 0.71. In comparison, the 1.25% of body weight group weighed out at 128.92 pounds (58.6 kilograms) with an average daily gain of 0.79 pounds per day (0.36 kilograms) and a gain to feed ration of 0.55.
When the calves’ body compositions were evaluated, fat content of the whole body was greater at greater feeding rates, while protein and water composition declined at greater feeding rates. Additionally, efficiency of fat and protein use climbed as feeding rate went up.
In those first weeks of life when calves get most of their nutrition from milk or milk replacer, farms are presented with the greatest opportunity for growth. These researchers would suggest it’s in the form of feeding higher energy feeds early.
