Three studies that compared free choice or high levels of whole milk compared to a marginal amount of soy protein-based, low fat milk replacer.
It is important to understand that all three of these studies were conducted at the same research center in Israel, with its unique management and feeding systems. It should not be expected that the milk replacers commonly used in North America or Europe will react in the same manner.
Israeli researchers fed 40 Holstein calves milk replacer or allowed them to nurse in pairs. Milk replacer contained 23% protein and 15% fat, and calves received 1.5 L/day from day 5 to 9, 2 L/day from day 10 to 14, 3 L/day from day 15 to 50, and 2 L/day from day 51 to 60. Calves allowed to nurse were placed with a cow for 15 minutes 3 times each day from day 5 to 42; from day 43 to 50 these calves received 4 L/day of milk replacer, and from day 51 to 60 they received 2 L/day of milk replacer.
Assuming 12% total solids concentration, milk consumed by calves contained 27.3% protein and 26% fat on a dry matter basis. All calves were weaned at 60 days. Water, starter (16% protein), and hay were available beginning at day 4; however, none of the nursing calves consumed starter or hay. Twenty nine heifers completed their first lactation.
Heifers that had nursed were 31 days younger at first calving (P = 0.05), but there were no differences in body weight between treatments. Actual milk production in a 300-day lactation tended to be higher for the nursed group than the milk replacer group (difference of 998 lbs; P = 0.08).
In another Israeli study, 40 Holstein calves were fed either milk replacer (23% protein, 12% fat; fed 1 lb of powder per day) or fresh milk (27% protein, 28.7% fat fed 2 times per day, calves allowed to consume as much as they wanted for 30 minutes each time). Both groups of calves had free access to 18% protein starter and water and were weaned at 60 days of age.
First lactation data was available for 34 heifers. Age (23.3 months) and body weight (1,129 lbs) at first calving were similar for calves fed milk or milk replacer. Actual 305-day milk production was also similar for the two treatments (25,142 lbs). However, milk fed calves produced more fat and protein on a daily basis and had higher daily average of 3.5% fat-corrected milk (68 vs. 65 lbs/day; P < 0.01).
In a similar study, also conducted in Israel, fed milk or milk replacer was fed to 46 calves. Both feeds were offered ad lib 2 times each day for 30 minutes each time, and calves were weaned at 60 days of age. Milk replacer in this study contained 24% protein and 13% fat, and milk contained 26% protein and 29% fat on a dry matter basis.
All calves had access to 18% protein starter and water.
First lactation information was available for 36 heifers. Age at first calving (24 months) was similar for all heifers, but those fed milk during the pre-weaning period tended to have greater body weight (1,210 vs. 1,162 lbs; P = 0.10). Over the 305- day first lactation, average daily actual milk (66 vs. 72 lbs/day) and 4% fat-corrected milk (62 vs. 67 lbs/day) yields were greater for calves fed milk than those fed milk replacer (P < 0.01).
In summary, these three studies from the Volcani Center in Israel showed that feeding high rates of whole milk that contained high protein and energy levels had positive effects compared to feeding low levels of milk replacer that contained some non-milk protein and had low levels of fat (12, 13, or 15%).
For those in North America and Europe where our milk replacers are often very different in composition, we should not conclude that milk replacer is bad for calves. In addition, we should not conclude that providing high levels of whole milk is the right approach for feeding young calves. These calf diets compared a high level of whole milk with milk replacers containing lower levels of nutrients than what is found in milk replacers sold in the US and Europe.
ABSTRACTS
In addition to the studies described above, there have been several meeting abstracts presented on this topic. Abstracts provide a short summary of an experiment. They do not have the detail that is available in a full-length paper and have not been subjected to peer review, the process of other scientists validating the research methods and conclusions. Many studies are initially presented as abstracts and later published as full papers, and information from abstracts should be considered preliminary.
Ballard fed 60 Holstein calves 1 of 3 milk replacer programs: 27% protein, 20% fat fed at an increasing percentage of body weight (1.5% in week 1, 2.25% in weeks 2 through 5, and 1.25% from week 6 to weaning); the same milk replacer fed at 0.88 lbs of powder per day for 2 weeks and then 1.10 lbs of powder per day through weaning; or 27% protein, 15% fat milk replacer fed at the same increasing percentage of body weight as described above.
First lactation data for 51 heifers was available. No difference was observed in age or body weight at first calving (25.4 months, 1,443 lbs). Actual milk production through 200 days was 1,449 lbs greater for calves fed 27/20 milk replacer at an increasing rate than the other treatments (P = 0.04). Production of 3.5% fat-corrected milk tended to be higher for these calves as well (difference of 1,558 lbs; P = 0.10).
British researchers looked at first lactation performance of cows fed the same 26% protein, 16% fat milk replacer free choice or at 1 gallon per day through 6 weeks of age. After weaning calves were managed similarly. There were no differences between treatments in age at first breeding (13.8 months), age at first calving (23.6 months), daily milk production (60.8 lbs), total first lactation milk yield (20,163 lbs), or calving interval between the first and second calf (12.8 months).
Drackley e also compared first lactation performance for calves fed control or intensified diets in 2 trials with similar treatments. Control calves received 22% protein, 20% fat milk replacer at 1.25% of birth weight and were weaned at 5 weeks of age. Intensive calves were fed 28% protein and 20% fat milk replacer at 2% of birth weight for 1 week then increased to 2.5% of body weight in weeks 2 through 5 (in trial 1 amount fed was adjusted weekly, in trial 2 it was held at 2.5% of week 2 body weight); calves were weaned at 6 weeks. For all calves, milk replacer was reduced by half in the week before weaning.
Both groups had free access to starter. Calves were managed in groups by treatment until 12 weeks, and then managed similarly to calving. There was no difference between treatments in age (25 months) or body weight (1,252 lbs) at first calving. Actual 305- day milk production was 1,723 lbs greater for calves fed intensively (19,745 vs. 21,468 lbs; P < 0.01).
A study of 140 Danish Black and White calves found that heifers fed milk ad libitum for the first 6 weeks of life tended to produce more milk per day (3.5 lbs) in their first lactation than heifers fed a constant level of 10 lbs (approximately 1.2 gallons) of milk per day (P < 0.10). In the same study, feeding milk ad libitum for 12 weeks reduced milk production by 5.7 lbs/day in first lactation (P < 0.02).
In another study from Denmark whole milk was fed to two groups of Danish Black and White calves (20 calves total). One group suckled the dams 60 minutes per day through weaning at 6 to 8 weeks of age and the other was bucket fed approximately 1.2 gallons of milk per day through weaning at 6 weeks of age. First lactation production through 250 days in milk was not different for daily milk (P = 0.19) or energy- corrected daily milk (P = 0.15).
Finally, there is one abstract on this topic that describes a study using regression analysis to evaluate the relationship between average daily gain (ADG) before weaning and first lactation milk production. Results of a regression analysis do not describe cause and effect, but they can provide insight on the strength of a relationship between various factors in a statistical model. In this study, lactation records from 792 heifers were analyzed. Preweaning ADG ranged from 0.29 to 2.71 pounds and was identified as a highly significant factor influencing first lactation milk yield.
The conclusion of the abstract was that increased growth rate, primarily through increased liquid feeding rate, had positive effects on milk yield. However, there are factors other than the amount of liquid feed that determine ADG, including illness, environmental stress, grain intake, and genetic propensity for growth. The abstract does not indicate that these factors were considered in the analysis. Therefore, while these results are interesting, they should be applied with caution.
