Yield and Composition of Milk from Various Two-Breed Cross Cows2

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Abstract
Milk yield and composition were estimated monthly from April through September for 71 4-year-old cows of eight crossbred groups: Hereford × Angus (HA), Angus × Hereford (AH), Simmental × Angus (SA), Simmental × Hereford (SH), Brown Swiss × Angus (BA), Brown Swiss ✕ Hereford (BH), Jersey ✕ Angus (JA) and Jersey × Hereford (JH). Milk yields were estimated by machine milkout following a 1.5-mg injection of syntocin. Milk yield was highest for J A and BA cows (average 8.09 ± .41 kg/day), intermediate for JH, BH, SA and SH crosses (average 7.38 ± .41 kg/day) and lowest for HA reciprocal crosses (6.52 ± .40 kg/day). Differences among crossbred cow groups in butterfat percentage and daily butterfat production were not significant. Milk protein production varied from .28 ± .01 kg/day for Jersey crosses to .21 ± .01 kg/day for HA reciprocal cross cows. Other groups were intermediate in milk protein production (average, .24 ± .01 kg/day). Jersey cross, Brown Swiss cross and SA produced most total solids (average, 1.03 ± .06 kg/day), while HA, AH and SH cows averaged .89 ± .06 kg/day. As cow-calf separation time increased from 6 to 9 to 12 hr, estimates for all milk traits decreased; however, the effect of length of separation on protein percentage was not significant. Cows in the 6-hr separation group had estimated daily milk yields 1.04 kg higher (P<.05) than those of cows in the 12-hr separation group. Correlations between calf weaning performance traits and milk traits expressed in kilograms per day tended to be higher than correlations between calf traits and milk composition traits expressed in percentages. Copyright © 1981. American Society of Animal Science. Copyright 1981 by American Society of Animal Science

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