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Nutrition Same diet, different results

00:00AM Sep 20, 2008

If you feed the same diet as your neighbor, you both should get the same milk production, right? Not necessarily.

A study from Spain published in the August 2008 issue of the Journal of Dairy Science looked at nondietary factors related to differences in milk production among herds fed the same diet. Researchers surveyed 47 dairy farms feeding the exact same diet for more than eight months preceding the survey.

A total mixed ration (TMR) containing all forages and concentrates was mixed at a local feed cooperative and delivered to farms daily. Milk production on the herds ranged from 45 to 74 lb./cow/day.

More than 50% of the milk production differences among the farms was attributed to animal management and housing factors. The most important factors were heifer rearing, presence of feed refusal in bunks, push-up of feed and the number of free stalls available per lactating cow.

The average age heifers were bred was 16.9 months with an age at first calving of 27.7 months. Both management practices had a negative impact on milk production and were beyond current recommendations of calving heifers at 23 to 24 months of age. For every month older than 24 months at calving, milk production on the farm dropped by about 1.1 lb./day.

The amount of TMR dry matter (DM) that was delivered to the lactating cows on these farms ranged from 36 to 55 lb./cow/day. As most dairy producers would expect, the higher-producing herds had a larger amount of TMR delivered per day than the lower-producing herds.

All herds were fed once per day. Those herds assuring some weigh-back before the next day's feeding averaged 3.5 lb. more milk/cow/day than those with slick bunk management. No estimate on the amount of feed weigh-back is given in the study. But simple economics indicates that if milk is $0.18/lb. and feed DM is $0.10/lb., a 2% feed weigh-back per day would be a good target.

Only 10% of the herds in the survey did not push up feed at least once per day. Time and labor to push up feed was a good investment for producers as the herds that pushed up feed averaged 8.6 lb./cow/day more milk than those that didn't. Pushing feed up more than once per day, however, did not have any additional positive effect on milk production.

Eighty-five percent of the herds in the survey housed cows in free stalls. Although herd size was small (averaging 68 lactating cows), the findings, I believe, are applicable to our lactating and fresh cow groups.

Milk production was positively correlated with number of stalls and number of milking cows. As cow numbers increased above one stall per cow, milk production declined. However, no relationship to milk production was found for herds with more than one stall per cow.

The data provides a strong indication that overstocking negatively affects milk production. It also suggests that cows need a well-maintained stall and their own space for comfort and optimum milk production.

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