British Beef Research Articles

Beef Milk Production for Maximum Efficiency

The goal for milk production in the commercial cow herd depends on the reflection of this milk in the performance of the calf, both pre and post weaning, and on the reproductive performance of the cow. Evidence suggests that the composition of the steer at a particular weight is not drastically dependent on the nutritional environment up to weaning. This means that the lean tissue growth can be had when the gain is most economical. The efficiency of utilizing gross energy through the cow in milk to the calf probably is competitive with the energy utilization by the calf itself. If low quality roughage, that can be harvested only by the cow, is considered, a good case for milk efficiency can be built. Milk production in excess of growth demands by the calf seems of little economic value since this results in less efficiency in the feedlot and lower prices per pound at weaning. The ceiling to milk production in the commercial cow herd is natural selection for reproductive performance. With a fixed calving season in a particular feed environment, an excessive level of milk production can result in a reduced calf crop. This level varies from extensive systems, utilizing natural ecologies where the cow herd must be adapted to the conditions, to intensive systems that utilize stored feed and an attempt to increase unit output rather than volume for improved net returns. As the cow-calf operation invades the more traditional farming areas where the capability for forage and grain production are great, a need will exist first for more rapid early growth and next for more maternal performance to exploit the potential, provided this is more economical than artificial feed environments. Vertical integration will allow exploitation of the most economical portions of the growth curve be they either pre- or post-weaning in a given circumstance. Several courses are open to improve maternal performance. Selection for weaning weight results in more accurate selection for pre-weaning growth than for maternal performance. Thus, the potential to utilize the maternal performance is there before it is available. Production of milk can be introduced quickly by using dairy breeding. Optimum levels need to be quickly established either by decreasing milk production or by improving the management system. Crossbreeding systems can both introduce milk and produce heterosis for the reproductive complex. The more extensive opertions are more dependent on maternal ability for increased calf weights yet are tied to a level commensurate with the feed resources to maintain reproductive performance. The more intensive operations are less dependent on maternal ability because of creep feeding, harvested feeds, and the possibilities of vertical integration; but they can utilize a higher level of maternal performance and still maintain reproductive performance should such prove to be the most economic segment of the growth curve in their particular system. Although maximizing milk production as a goal seems improper, this is not to say that the British beef breeds do not need both the growth potential to utilize it and some more maternal ability to exploit even under many conventional systems of beef production.

Interrelationships of Erythrocyte Characters and Other Characters of British and Zebu Crossbred Beef Cattle

The following red cell characters were studied in a herd of 217 calves repre-senting Brahman cross, Africander cross, Grade Brahman, and British (Hereford X Shorthorn) breeding, and in their dams: packed cell volume, haemoglobin level, red cell count, fragility, potassium and sodium concentrations, catalase activity, and haemoglobin type. There were distinct breed differences. In some characters, e.g. packed cell volume and potassium concentration, Africander cross were inter-mediate between Brahman cross and British, whereas in others, e.g. fragility and catalase activity, they were indistinguishable from British. Within breeds, the characters showed highly repeatable differences between animals and high herita-bilities.