Effects of feeding energy or protein supplements before or after calving on performance of spring-calving cows grazing native range

Abstract

In three consecutive years, spring-calving Hereford and Hereford x Angus cows (n = 348) were used to determine effects of level of supplemental energy or protein before and after calving on cowherd performance. Beginning on November 1, cows were individually fed 1.22 kg/d of a 40% CP (PROTEIN) or 2.44 kg/d of a 20% CP supplement (ENERGY) until calving. After calving, cows remained on the same supplement, were switched to the other supplement, or were fed 2.44 kg/d of a 40% CP supplement (HI PROT). Supplementation ended on April 20, the start of a 65-d breeding season. Cows fed ENERGY during gestation had greater BW gains (9 kg) at calving than PROTEIN-fed cows (P < .01). Calf weaning weight was not affected by supplementation. Cows fed ENERGY before calving had an 11% greater pregnancy rate than the cows fed PROTEIN (P < .002). Cows fed PROTEIN or ENERGY after calving had similar BW gains but cows fed HI PROT after calving lost less BW during supplementation (P < .002). Pregnancy rates were not influenced by treatments fed for a short period after calving. In conclusion, conception rates were significantly improved by feeding greater levels of supplemental energy prepartum but not postpartum. Energy supplements can affect reproduction with minimal effects on BW or condition.

Effects of protein-free energy supplementation on blood metabolites, insulin and hepatic PEPCK gene expression in growing lambs offered rice straw-based diet

“…This result was in agreement with Barton et al (1992) and Yelich et al (1995Yelich et al ( , 1996. The response of insulin to supplemental cornstarch may result from a higher supply of gluconeogenic precursors and insulinotropic factors (Trenkle, 1978;Harmon, 1992;Marston et al, 1995), especially when the supply of energy was very high (e.g. 180 g/day of starch in this study).…”

Influence of post-calving supplemental protein on calf performance and reproductive efficiency for beef cows fed silage

“…Other protein-evaluation systems account for this (Agricultural and Food Research Council [AFRC] 1992) and our data indicate that for lactating beef cows fed silage, protein supply to the small intestine limits calf growth because of limited milk production. In dairy cows, silage diets of similar quality can support about 14 kg milk d -1 without supplementation (Rae et al 1987). While this is still considerably higher than the levels predicted here, the higher intake capacity of dairy breeds per unit metabolic weight and their larger frame size must be taken into account.…”

“…For cows calving in good condition, sufficient energy reserves can be drawn upon to compensate for a limited For personal use only. energy supply in the diet (Houghton et al 1990;Marston and Lusby 1995). When energy reserves at calving are insufficient to compensate for a limited energy intake postpartum, responses in calf gain to energy have been observed (Bartle et al 1984;Houghton et al 1990;Laflamme and Connor 1992).…”

“…to reduce conception rates in beef (Marston et al 1995) and dairy cows (Elrod and Butler 1993), especially if inadequate energy is supplied to the rumen. However, the results of our study suggest that the negative effect of protein on pregnancy establishment is dependent on ME relative to protein intake and excessive loss in body condition.…”

“…Nutrient requirements of beef cows are low relative to other classes of ruminant livestock (National Research Council [NRC] 1989;1996). Consequently, there is considerable research on exploiting inexpensive feedstuffs of low nutritional value and the problems of undernutrition.…”