Effect of energy and protein on estrus, conception rate, growth and milk production of beef females.

T HE reproductive performance and milk production of beef females is closely associated with nutritional status. Swanson and Hinton (1964) found that dairy heifers reared on a subnormal feeding regimen produced less milk than their twins which were fed normally. Blakely (1964) and Wiltbank, Bond and Warwick (1965) have associated anestrus and delay in puberty with a low plane of nutrition. Buchanan-Smith et al. (1964) reported a "triggering effect" on the incidence of estrus when an all-concentrate diet was fed. Swanson (1960) and Arnett (1963) with dairy and beef heifers, respectively, reported a decrease in milk yield in over-fat heifers. The present studies were conducted to (1) observe the effects of feeding different levels of protein and energy on milk production, body weight of the dam and growth of the calf and (2) evaluate continuous vs. compensatory growth and an all-concentrate vs. a conventional diet on the estrous cycle and conception rate.