Jm. Akayezu et al., YIELD RESPONSE OF LACTATING HOLSTEIN DAIRY-COWS TO DIETARY FISH-MEAL OR MEAT AND BONE MEAL, Journal of dairy science, 80(11), 1997, pp. 2950-2963
Experiments were conducted to examine the effects of the source and am
ount of dietary protein on yield and composition of milk from Holstein
dairy cows. Study 1 used 36 multiparous cows at 125 +/- 59 d in milk
in a replicated 2 x 2 Latin square design. Treatments were diets formu
lated to contain 16% crude protein (CP) in which 11% was fish meal or
meat and bone meal supplied 11% of dietary CP. Intakes of dry matter,
CP, and net energy for lactation; yields of milk; and percentage of mi
lk fat were not affected by treatment. Fish meal increased contents of
milk total N, casein N, and noncasein N but did not increase contents
of NPN; fish meal also tended to increase milk CP yields. Study 2 use
d 78 cows (31 primiparous) at 31 +/- 2 d in milk in a randomized block
design. Two treatment diets were formulated to contain 16 or 18.5% CP
, and soybean meal was the sole source of supplemental protein in thos
e diets. The two other treatment diets were formulated to contain 16%
CP; in these diets, fish meal or meat and bone meal partially replaced
soybean meal. Treatments did not influence yield or composition of mi
lk from multiparous cows. Compared with a soybean meal diet containing
16% CP, a soybean meal diet containing 18.5% CP or diets containing 1
6% CP and containing meat and bone meal or fish meal increased the mil
k yield of primiparous cows similarly. Fish meal or meat and bone meal
increased the efficiency of protein utilization for milk yield.