Comparison of Complete Feed Rations to a Conventional Ration for Lactating Cows

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Abstract
Sixteen high-producing Holstein cows were used in a ll0-day continuous trial to compare the effect of feeding three com- plete feeds containing different sources of roughage (alfalfa, cottonseed hulls or na- tive grass hay) with a conventional system of feeding roughage and concentrate sep- arately on intake of feed, total digestible nutrients and digestible energy, milk yield and composition, gross feed conversions, body weight changes, digestibility of the rations and health of the animals. All ra- tions contained 30% roughage and 70% concentrate, and were fed ad )ibitum. The cows receiving the cottonseed hulls ration consumed significantly (P < .05) more feed than the other groups, but no differences were observed in TDN and DE intake for any of the rations. No significant differences were observed on milk produc- tion, FCM, or milk constituents; however, cows fed the native grass hay ration had a significantly (P < .05) higher SNF per- centage. There were no significant dif- ferences in the gross feed efficieneies of the animals on any o£ the rations. No significant differences in body weight gains of the animals were obtained. There were significant (P < .05) differences ~ in the TDN coefficients in the rations; the the- oretieal TDN values overestimated the actual TDN values, especially those of the rations containing cottonseed hulls and native grass hay. Some health problems such as foot rot, stiffness of the joints and mastitis were encountered in a few animMs in this study.