An overview of four years of calf research at SROC
The University of Minnesota Southern Research and Outreach Center (SROC) Calf and Heifer Research and Extension facility in Waseca contract raises over 800 dairy heifer calves annually for three Southern Minnesota commercial dairy operations. Since 2004, completed nursery (56 days) and post weaning (up to 112 days) applied studies have been conducted involving over 3,000 heifer calves. Calves are picked up twice weekly at 2-4 days of age and remain at SROC until 6-7 months of age with the goal of providing high quality heifers when transferred to next stage growers. Upon arrival at SROC, calves are weighed, hip heights taken, and a jugular blood sample drawn. The sample is used to check total serum proteins using a refractometer (see Table 1 for calf profiles). Overall calf losses at SROC are < 2%. Currently, DHIA records are being used to document calving age and first lactation performance of all heifers back to their respective dairy herds.
|Table 1. Profile of heifer calves contracted at SROC from 3 dairy farms from 2-4 days up to 6 months of age.|
|Item||Farm A||Farm B||Farm C|
|A. Upon arrival|
|Number of heifers||885||1,593||978|
|Initial BW, lb||88.8||86.7||87.2|
|Initial serum protein, g/dl||5.4||5.4||5.2|
|Initial serum protein profiles||—||—||—|
|B. 6 month profile of 2,397 heifers|
|Final BW, lb||476||462||451|
|Final hip height, in||45.5||44.9||45.1|
|Total ADG, lb||1.92||1.91||1.91|
Calf Nursery Research Studies. A target goal for calf performance is to double the initial body weight and gain at least 4 inches of frame height by the end of the nursery phase. These goals have been attained in a number of calf groups but there are some variations by season of the year. Studies have been designed to provide options for both milk replacer (MR) and calf starter programs in relationship to calf performance, health, and potential changes in economic efficiencies.
- Conventional vs intensive MR programs. Calves on an intensive program had 20% better performance than those fed the conventional program but with higher costs of gain. Calf health was not affected and there were no differences in post weaning performance from 9-25 weeks of age. A complete analysis of raising costs should be used for the most viable cost:benefit ratio for each of the MR programs based on first calving age and lactation performance.
- Alternative protein and energy sources in MR. Calves fed an all-milk protein 20:20 MR had 10% better growth to 56 days than calves fed MR containing alternative protein sources including hydrolyzed wheat gluten and soybean protein concentrate substituted at various percentage levels. Calf performance was not influenced when using animal vs vegetable fats in MR. The average frame growth exceeded 4 inches and overall gain was within the range of other studies.
- Additives in MR as well as various feeding strategies. Focus is on nutritional management for calf health, intestinal health and/or immune function during the nursery phase. To-date additives have not influenced pre- and immediate post-weaning calf performance. Other recently completed or on-going studies are investigating nutritional additives incorporated with different MR feeding rates. The implications on calf performance by varying the number of milk feedings per day are also being documented.
- Calf starter programs. Offering a high quality calf starter and promoting optimal intake is integral to the success of SROC nursery feeding programs. Under the SROC program, calves are weaned by days on feed rather than CS intake. Good CS intake could allow for earlier weaning and reduce extra costs of extending the liquid feeding period (see Table 2 for CS intake profiles).
- Calf starter composition and physical form. Preliminary data suggests that several corn processing and physical forms allow good calf performance. Calves fed CS based on steam flaked corn, pellet and oats, whole corn and pellet, or roasted corn, pellet and oats performed equally as well.
|Table 2. Average pre- (1-42 days) and post-weaning (43-56 days) calf starter (CS) intake by 14-day periods and season of the year across recent SROC studies 2004-2006a.|
|Time of year||No. calves||20:20 MR lbs/day||CS CP%||Day 1-14||Day 15-28||Day 29-42||Day 1-42||Day 43-56|
|a Adapted from Chester-Jones (2007).|
|b Non-medicated milk replacer.|
Postweaning Studies. On-going SROC research is looking at various transitional management and feeding strategies-a challenge on many dairies. Once in group pens, heifers are typically fed grain mixes with access to hay.
- Feeding regimens. Protein sources (dried distillers grains and urea), grain mix protein levels (13,16,19% CP), rumen fermentation enhancer, fiber levels, and limit vs full feeding grain mixes have been investigated. Regardless of feeding regimen, heifer DM intake consistently represents close to 3% of body weight.
- Forage quality. A study using a 16% CP cracked corn and pellet grain mix for 112 days (6 lb/day for days 1-14 and 4 lb/day from days 15-112), along with either a 100 RFV hay, 130 RFV hay, or 154 RFV hay showed some increased daily gain and feed efficiency as the RFV increased. Heifer performances were acceptable and an economic comparison should be the criteria to select the hay of choice when limit feeding concentrates.
In summary, options have been investigated at SROC over the past four years to support improvement in consistency of nutritional management for calf raising programs from 2-4 days up to 6 months of age to optimize the growth and health of dairy calves.
For further details on these studies, contact Hugh Chester-Jones or Neil Broadwater.
Published in Dairy Star July 3, 2008