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Yield and Composition of Milk from Various Two-Breed Cross Cows^1,2,

Oklahoma Agricultural Experiment Station, Stillwater 74078

Abstract

Milk yield and composition were estimated monthly from April through September for 71 4-year-old cows of eight crossbred groups: Hereford x Angus (HA), Angus x Hereford (AH), Simmental x Angus (SA), Simmental x Hereford (SH), Brown Swiss x Angus (BA), Brown Swiss x Hereford (BH), Jersey x Angus (JA) and Jersey x 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.

¹ Journal Article 3710 of the Agr. Exp. Sta., Oklahoma State Univ., Stillwater. Research was conducted by the Anim. Sci. Dept, (Project 1502) in cooperation with USDA, SEA, Southern Region and contributes to the Regional Beef Cattle Breeding Project, NC-1.

² The authors gratefully acknowledge the assistance of Dr. Ronald W. McNew, Statistics Dept, Oklahoma State Univ., for statistical consultation; Dr. Lavoy I. Croy, Agronomy Dept., Oklahoma State Univ., for assistance in determining milk protein content in his laboratory, and Dr. Jack Stout, Director of the DHIA Testing Lab, for determining butterfat composition.