MINNEAPOLIS — During the past few years, higher levels of milk or milk replacer have been recommended to achieve greater pre-weaning growth of calves and to increase milk production of first-lactation cows. Excellent first-lactation production is a key component of dairy farm sustainability. Some studies have indicated that improvements in calf growth are associated with higher first-lactation production, but others have disagreed. Recently, Penn State researchers (Gelsinger et al., 2016) indicated that although pre-weaning average daily gain is positively related to first-lactation milk production, there are more important factors in determining first-lactation performance than pre-weaning calf growth.
We evaluated the relationships between early life growth and first-lactation production of Holstein dairy cows from commercial dairy farms in Minnesota. These calves were enrolled in calf research trials at the University of Minnesota Southern Research and Outreach Center (SROC) in Waseca, MN. Calves were contract raised for three commercial dairy farms which represent over 2,000 dairy cows. Heifer calves were picked up twice a week at 2 to 5 days of age and taken to the SROC. For our study, data were collected from 2004 to 2012 for 2,880 Holstein animals. The calves were enrolled in 37 different calf research trials at the SROC from 3 to 195 days of age. At the end of the trials, calves were group housed and returned to their respective farms or moved to heifer growers at about 6 months of age. Milk replacer fed to calves included varying levels of protein and amounts fed, but in the majority of studies, calves were fed a milk replacer containing 20% fat and 20% protein at 1.25 pounds per calf daily. Most calves (93%) were weaned at 6 weeks of age. Average daily gain at 8 weeks for the 2,880 calves was 1.4 pounds per day.
The results show that calf growth had a significant positive effect on 305-day first lactation milk, fat, and protein production. For every 1 pound of average daily gain at 8 weeks of age, milk production increased by 1,276 pounds in first lactation. To put this in perspective, if a farm increased their calf average daily gain from 1.5 to 2.0 pounds per day, first lactation milk production in 305 days would increase by only 648 pounds. The variation in milk production and average daily gain was high, and this suggests additional factors impact first lactation performance (i.e. environment, feed quality, housing, and animal health). Figure 1 shows the relationship between 8-week average daily gain and 305-milk production in first lactation. There was great variation for calf growth and milk production. In Figure 1, we observe that calves that achieve a 2-pound average daily gain may have 15,000 or 30,000 pounds of milk in first lactation.
Intake of calf starter had an impact on first-lactation production while milk intake, which varied less, had no effect. Each additional pound of calf starter DM intake at 8 weeks of age resulted in 18.1 pounds more milk in first lactation. Therefore, calf starter intake may be a better indicator of future milk production than just average daily gain alone. Furthermore, we found that calves born during the fall and winter had greater starter intake and average daily gain at 8 weeks. However, calves born during the summer produced more milk in 305 days during their first lactation than those born during the fall and winter. From this study, it may be difficult to be confident in the prediction equations generated for calf growth versus first lactation performance because of the high variation in calf growth and production. Therefore, excellent colostrum and disease management, hygiene, milk replacer quality and consumption, calf starter quality and consumption, water quality and access, and post-weaning nutrition are all necessary to achieve optimal heifer growth and future milk production.
— Brad Heins and Hugh Chester-Jones, University of Minnesota Extension
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