Latest Developments in Calf and Heifer Research
Posted: August 5, 2008
The American Dairy Science Association held its annual meeting in Indianapolis, Ind., in July. Here’s a look at some of the latest research into nutrition and management of dairy calves and heifers.
Penn State studies confirmed that colostrum can be pasteurized successfully and showed that heating colostrum at 140°F for 30 to 60 minutes was the optimum time and temperature combination to reduce bacteria counts without affecting colostrum IgG levels or viscosity. In a subsequent study, calves fed colostrum heated at 140°F for 30 minutes had significantly higher serum IgG levels at 24 hours compared to calves fed unheated colostrum (22.6 and 19.6 g/L, respectively). Total serum protein in the two groups of calves was similar at 24 hours and averaged 5.55 g/dL. The higher blood Ig levels remained for the first 4 weeks of age. Calf body weight was similar for the two treatments through 6 weeks of age.
Colostrum in these studies was not heated in a commercially available pasteurizer. However, a small batch pasteurizer with adjustable temperature controls is recommended because colostrum must be heated at a lower temperature than used for milk. Agitation of colostrum is another important pasteurizer feature that allows even heating. Rapid cooling of colostrum after pasteurization also will help prevent damage to proteins.
Milk Replacer Formulation
Researchers from Akey presented amino acid requirements for milk-fed calves less than 5 weeks of age. Data in this area is scarce in the scientific literature, especially for calves fed both milk and grain. In a series of four experiments, calves were fed milk replacer (all protein from whey) and calf starter (18% crude protein). Based on weight gain and feed efficiency, their results showed that a 26% protein, 17% fat milk replacer fed at 1.5 pounds per day needed to contain 2.34% lysine and 0.72% methionine. Feeding higher levels of protein or amino acids did not improve average daily gains or efficiency.
Record-high milk replacer prices in the last year have likely caused you to consider products with alternative protein ingredients; after all they often cost considerably less. Two studies presented the results of feeding milk replacer containing wheat protein. The first trial was conducted by Akey scientists and evaluated a 26% protein, 17% fat milk replacer with 0, 6, or 12% of the protein provided by hydrolyzed wheat gluten.
Calves started the experiment at 2 to 3 days of age and were weaned after 42 days. As the amount of wheat gluten in milk replacer increased, calf growth and starter intake declined. Average daily gain was 1.4 lb/d for the all-milk treatment and 1.1 lb/d in calves fed milk replacer with 12% of protein from wheat. Weight gains after weaning were not different for the three treatments. Another trial, reported by Vigortone researchers, compared calves fed milk replacer containing 22% protein and 18% fat with 50% of the protein provided by hydrolyzed wheat protein to calves fed 22% protein and 20% fat with all milk protein.
Calves started the trial at about 10 days of age and were fed for 35 days. In this experiment calves fed both milk replacers gained about 1.2 lb/d, and calves fed wheat gluten tended to eat more starter. The trend for improved grain intake may have been due to the lower fat content of the wheat protein milk replacer. The most likely reason for the different results in these two trials is the age of calves. In the first two weeks of life calves have a limited ability to digest non-milk proteins. The Akey trial included these first two weeks of life, while the Vigortone trial started near the end of that period. Taken in combination, these trials support current recommendations to avoid non-milk proteins for young calves but consider their use for older calves as a strategy to reduce milk replacer costs
Rice protein concentrate also was evaluated by Akey. The experiment was similar to the one described above for wheat protein, but rice protein contributed 0, 8 or 16% of the crude protein in milk replacer and calves were weaned after 28 days in this trial. Calves fed rice protein concentrate gained less weight and were less efficient than calves fed 100% whey protein; average daily gain was 0.86 lb/d for milk protein-fed calves and 0.39 lb/d for calves fed milk replacer with 16% of the protein from rice. Again, the age of the calves is likely part of the reason for this poor weight gain. These results do not support using rice protein in a 4-week weaning program
Performance of Pasteurizers on the Farm
A field study of calf milk pasteurizers on 6 Pennsylvania farms found total bacteria counts were reduced to less than 10% of the original level in about 80% of the samples tested. However, on two farms pasteurization failed to reduce bacteria counts in about half of the samples tested. This study reinforces the importance of carefully following pasteurization protocols and practicing good sanitation from collection through feeding.
Processing Grain for Calf Starter
University of Minnesota research showed that calves fed three different textured starters containing steam-flaked corn, pellet, and oats; whole corn and pellet; or roasted corn, pellet, and oats had similar weight gain before and after weaning. Although calves fed whole corn did eat less grain and gain less weight from day 29 to 42, there were no differences in weight gain over the complete 42-d milk feeding period. Calves were fed 1.25 lb/d of 20% protein, 20% fat milk replacer from 1 to 35 days of age, 0.63 lb/d from d 36 to 42, and weaned at 42 days. Calves gained about 1.5 lb/d over the 56 days studied. This confirms previous research that indicates that whole grains are digested efficiently by young calves and that processing grain is not needed pre-weaning
Grouping Strategies at Weaning Time
Grouping strategies for weaned calves were investigated by University of Minnesota researchers. Fourteen days after weaning (which occurred at 42 days) calves were grouped by one of three methods: moved from nursery barn to grower barn and into a group of 6 calves; remained in nursery barn and grouped with 6 calves; or remained in individual pens in nursery barn. Calves stayed in these treatment groups for 14 days. On day 15 all calves moved to the grower barn, and individually housed calves were placed in groups of 6. Calves received a 20% protein, textured starter for 7 days, followed by 17% protein whole corn and pellet mix for another week. After this feed transition, calves were fed the grain mix and free choice hay through 6 months of age.
Regardless of grouping strategy, calves gained 2 pounds per day in the first two weeks of the experiment. After the first two weeks, calves moved out of the nursery barn and into groups gained 0.09 pound per day more than calves grouped in the nursery barn and about the same amount as calves housed individually through 6 months of age. Individually housed calves were the most feed efficient during this same time period. These results demonstrate several alternatives for grouping calves after weaning and that many systems can work equally well, provided some basic principles are followed. It is important to notice that all three methods were designed for successful weaning transition with small groups of only 6 calves and gradual feed changes using high quality feeds and forages.
No Supplemental Phosphorus for Heifers
Wisconsin and Michigan researchers investigated the need for supplemental phosphorus in heifer diets. The NRC requirement for phosphorus is 0.20 to 0.35% of ration dry matter, and many feeds contain phosphorus at or above that level. In fact, because of the phosphorus present in ration ingredients, it was not possible to formulate a diet with less than 0.28% phosphorus for this experiment. In this study, 183 Holstein heifers and 182 crossbred heifers were fed diets with no added phosphorus (0.28%) or with supplemental phosphorus (0.38%) from 4 to 22 months of age. Researchers evaluated frame growth by measuring hip height and width, body length, heart girth, cannon bone circumference, and pelvic length, height and width. Bone metabolism was measured in 64 heifers at 12 months, and bone density was measured in 32 heifers at 21 months.
Heifers fed supplemental phosphorus had slightly more phosphorus and magnesium in their bones than unsupplemented heifers. However, the amount of phosphorus in the diet did not affect bone growth, density, or metabolism in this long-term trial. Researchers concluded that supplemental phosphorus was not needed in this situation. The application of this research is fairly obvious; if ration ingredients meet heifers’ requirements, supplemental phosphorus can be eliminated. This can reduce feed costs and phosphorus excretion, which may be particularly helpful for farms under phosphorus-based nutrient management regulations.
Vaccine for Staph. aureus Mastitis in Heifers
Research conducted in Virginia evaluated the effectiveness of vaccination with a commercial Staphylococcus aureus bacterin (Lysigin, manufactured by Boehringer Ingelheim Vetmedica Inc.). Heifers were initially vaccinated between 6 and 18 months of age, followed by boosters 14 days later and at 6-month intervals until calving (if started at 6 months, each animal would receive 5 doses).
At calving 13.3% of vaccinated heifers had Staph. aureus mastitis, compared to 34.0% of control heifers. Vaccinated heifers also had fewer infections caused by coagulase negative staphylococci (64.2% of vaccinated versus 69.8% of control heifers), although the reduction was not as great as anticipated. Somatic cell counts (SCC) during the first week of lactation in both infected and healthy heifers were reduced by half due to vaccination. For heifers with Staph. aureus infections, vaccinated heifers had SCC of 441,764 compared to 892,176 cells/mL for controls. In healthy heifers, vaccinated animals had SCC of 66,095 versus 132,754 cells/mL in controls. Vaccinated heifers also produced 2,000 pounds more milk and were less likely to be culled in their first lactation than untreated heifers.
Coleen Jones, Research Associate and Jud Heinrichs, Professor of Dairy and Animal Science, Department of Dairy and Animal Science