Studies show a link between nutrient intake prior to weaning and long-term milk yield.
By Mike Van Amburgh, Emiliano Raffrenato and Bob Everett
Your treatment of calves from the first hour through the first six to eight weeks of their lives could impact their future milk producing ability.
Most dairy producers know the important relationship between calf health and growth and colostrum quality, yield and immunoglobulin (Ig) absorption. Low serum Ig status in calves relates to decreased growth rate and increased morbidity. Some studies even indicate that low serum Ig levels affect milk yield during first lactation.
A 1988 study indicated calves with higher Ig status are able to inactivate pathogens prior to mounting a full immune response. This allows them to maintain energy and nutrient utilization for growth But calves with low Ig status must first mount an immune response, diverting nutrients to defense mechanisms rather than growth.
How severe is this difference, or for how long does it persist? Data from a 1989 study demonstrated that for each unit of serum IgG content above 12 mg/ml, there was an 18.7-lb. increase in mature equivalent milk yield. This implies calves with lower IgG content were more susceptible to immune challenges, which impacted long-term performance.
A 2005 study suggests the impact of serum Ig levels wasn’t nearly as great, but still affected milk yield and survival through the second lactation. In that study, Brown Swiss calves received either 2 or 4 liters of colostrum just after birth. Researchers monitored the animals for two lactations after calving, making three observations:
1. There was a 30% increase in prepubertal growth rates based on colostrum feeding level under identical feeding conditions.
2. There was a 16% increase in survival to the end of the second lactation of calves fed the 4 liters of colostrum.
3. The surviving calves fed the 4 liters of colostrum produced 2,263 lbs. more milk by the end of the second lactation.
We don’t know if this response is due just to Ig status or other factors in colostrum. But it suggests colostrum quantity is important for long-term productivity, in addition to what we traditionally thought of as immune status.
Early eating, later production Many studies have allowed researchers to look at milk yield from cattle that received more nutrients up to eight weeks of age (see Table 1). In each study, increased nutrient intake prior to 56 days of age resulted in 1,000-3,000 lbs. of additional milk during the first lactation, compared to calves under more restricted feeding during the same period.
In a recent Miner Institute study in Chazy, N.Y., researchers report calves fed approximately 2 lbs. per day of milk replacer produced 1,543 lbs. more milk (at 200 days in milk) than calves receiving 1 lb .of milk replacer powder per day. Calving age wasn’t affected by treatment.
Averaging the studies shown in Table 1, there is a 1,700-lb. response to increasing nutrient intake prior to weaning. Here’s the take-home point: The higher intake levels must be from liquid feed.
We started feeding Cornell’s research herd for greater preweaning weight gains many years ago, and have more than 1,000 weaning weights and 725 lactations with which to make evaluations. We analyzed the lactation data of the 725 heifers with complete lactations, evaluating several factors – birth weight, weaning weight, height at weaning, weight at 4 weeks of age and others – related to early life performance and their milk yield.
Our data shows growth rate prior to weaning has the greatest correlation with first-lactation milk. For every pound of average daily gain (ADG) prior to weaning, the heifers produced approximately 1,000 lbs. more milk.
The range in preweaning growth rates among the 725 animals was 0.52 to 2.76 lbs. per day. Also, 20% of the variation in firstlactation milk production could be explained by growth rate to weaning. This has important ramifications:
• The impacts of Ig status and nutrient intake play a significant role in the performance and variation in first lactation milk yield.
• More milk will be achieved once we better understand the cause of the variation.
• To achieve these milk-yield responses from early life nutrition, calves must double their birth weight by weaning. This means milk or milk replacer intake must be greater than traditional programs for the first three to four weeks of life.
A closer look at some research
In the study by Rincker et al. (2006), control calves were fed a standard 20% crude protein (CP), 20% fat milk replacer and starter, at 1.2% of body weight (BW), to achieve 1-lb. per day growth rate to weaning. The treatment calves were fed a 28% CP, 15% fat milk replacer at 2.1% of BW and a higher protein starter (24.5%) to achieve 1.5-lb. per day gain prior to weaning. All calves were weaned by six weeks and fed similarly from eight weeks through the first lactation. Body weight at calving was not different – 1,265 vs. 1,241 lbs., respectively. Milk yield was followed only through the first 150 days of lactation. Projected 305-day milk yields were 1,100 lbs. greater for the heifers fed for the higher growth rates prior to weaning.
The response in the Moallem et al. (2006) study suggests milk replacer quality and protein status of the animal, post-weaning, were important to achieve the milk yield response.
Calves were fed a 23% CP, 12% fat milk replacer containing soy protein or whole milk. Post-weaning, calves were fed similarly until 150 days of gain, and the diets were protein deficient (~13.5% CP). Starting at 150 days, calves from both preweaning treatments were supplemented with 2% fish meal from 150 to 300 days of life.
Calves allowed to consume whole milk ad lib for 60 minutes, supplemented with additional protein, produced approximately 2,500 lbs. more milk in the first lactation.
In the Pollard et al. (2007) study, calves were fed either a conventional milk replacer (22:20) at 1.25% BW or a 28:20 milk replacer fed at 2% BW for week one of treatment. They received replacer at 2.5% BW from week two to five, and then were systematically weaned by dropping the milk replacer intake to 1.25% for six days.
All calves were weaned by seven weeks of age and, after weaning, managed as a single group and bred according to observed heats. The heifers calved between 24 and 26 months of age with no significant difference among treatments. Calving weights averaged 1,278 lbs. Milk yield on average was 1,841 lbs. greater for calves fed the higher level of milk replacer prior to weaning.