Importance of balanced nutrient intake from both milk and calf starter highlighted in research
Pre-weaning amount of milk replacer (MR) or whole milk and calf starter (CS; pre- and post-weaning) are the two most important factors for calf growth during the first two months in the nursery phase. Environmental conditions and health also contribute to calf performance responses. Offering a high quality CS and promoting optimal intake is integral to the success of all Southern Research and Outreach Center (SROC) nursery feeding programs. The rumen develops between four and eight weeks of age. This development is driven by consumption of dry feed.
The program focus for the University of Minnesota SROC Calf and Heifer Research and Extension Facility during the last 10 years has been contract raising commercial dairy heifer calves from three dairies totaling > 2,000 dairy cows. Calves are picked-up twice weekly at two to five days of age and contract raised until six months of age. All calves receive three feedings of colostrum on the farm by 24 hours of age. Nursery calves are housed in well-bedded individual pens in naturally ventilated curtain-sided calf barns. Options for group feeding include an automatic calf feeding system.
Nursery studies are typically 56 days with weaning at 42 days. Calves are moved from the nursery into one of two post weaning barns until they reach six months of age when they will be picked up by the dairies. Milk replacer studies have compared a conventional 20% protein:20% fat all-milk protein MR program to other options such as modified intensive or intensive feeding. Calf starters have typically been 18% crude protein varying in physical form and composition.
A target goal for SROC calf performance is to double the initial body weight by the end of the nursery phase and gain at least four inches of frame height in the same time period. These goals have been attained in a number of calf groups but there are some variations by season of the year. Balanced nutrient intake from both milk and calf starter is the best approach for optimum growth, rumen development and calf health. Milk feeding does not affect rumen development. The intake of milk is important for growth but starter intake and palatability is critical for the balance. Regardless of milk feeding program, offering calf starter at an early age will enhance rumen function.
Table 1 provides examples of recent milk feeding programs at SROC to illustrate the balance between MR feeding and starter intake to maintain good calf growth during different seasons of the year. The SROC conventional program using a 20% protein:20% fat MR is compared to moderately intensive programs. All programs feed MR twice daily for 35 days and half the amount from day 36 to weaning at 42 days. The CS in each example is a complete texturized 18% crude protein feed with no additives or with decoquinate included at 22.7 mg per lb.
Table 1. Recent examples of calf starter (CS) lb dry matter intake for various milk replacers (MR; 20 or 24% protein:20% fat) and feeding levels for 328 calves by season during 2012 to 2014 at the University of Minnesota SROC in Waseca.
|Months||MR||MR lb/d||MR lb
abcdMeans in the same column with different superscripts differ (P < 0.05).
The CS is very palatable and contains digestible fiber sources which have enhanced intake. The MR are all-milk protein and non-medicated. Since 2010, for the first 14 days after arrival, calves are each fed 10 mg per lb body weight of neomycin and oxytetracycline to control diarrhea. The 20:20 feeding examples indicate goals can be attained at both the 1.25 and 1.50 lb per day feeding rate. Feeding 20:20 vs. 24:20 at 1.25 vs. 1.50 lb per day can reduce CS intake but increase daily gain. However, calves only met frame growth goals when fed the 24:20 MR. When calves were fed a 24:20 at increasing amounts, CS intake decreased but growth tended to increase with MR feeding level and all calves met weight and frame size goals. The growth of calves at all MR levels exceeded many studies feeding an accelerated MR program.
Bottom line: balanced nutrient intake from both milk and calf starter is the best approach for optimum growth, rumen development and calf health. Good CS intake could allow for earlier weaning and reduce extra costs of extending the liquid feeding period.