The Influence of Initial Cow Weight on Progeny Performance and TDN Efficiency in Production of Slaughter Cattle

Data utilized in this study were from records (collected over a two-year period) of 45 Angus cow-calf pairs in which both the individual TDN consumption of the cows over a twelve month period and the individual TDN consumption of the calves from birth to slaughter (excluding TDN provided by milk) were recorded. The objectives of this study were to determine total digestible nutrient (TDN) consumed by cows of various sizes and weights, to determine the TDN intake of both cow and calf per unit weight of slaughter calves which varied in growth potential, to establish weights at which maximum TDN utilization occurred, and to establish relationships among characteristics of cows and calves, and overall TDN efficiencies for various periods.

Cows were selected at weaning, confined to individual pens and individually fed to the following weaning. Cows selected ranged in weight from 835 lb. to 1,195 lb. In addition to initial weight, skeletal measurements and subcutaneous fat deposition between the twelfth and thirteenth ribs were recorded at the initiation of each trial. Milk production of the cows were made at 28-day intervals.

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These results indicated that TDN efficiency at weaning was primarily a function of size of both the dam and progeny while at point of maximum TDN utilization, size of the dam and progeny exhibited very little influence on TDN efficiency.