The delivery of cottonseed meal at three different time intervals to steers fed low-quality grass hay: effects on digestion and performance.

A ruminal fermentation trial and a steer growth trial were conducted to evaluate the effects of time interval of cottonseed meal (CSM) supplementation of predominantly meadow fescue grass hay (GH; CP = 6.6%) on nutrient digestion and growth performance of beef steers. The fermentation trial used four ruminally cannulated steers assigned to a 4 x 4 latin square design with dietary treatments of GH fed alone (C) or GH supplemented with 3 g CP/kg BW.75 daily as supplied by CSM every 12, 24 or 48 h. Nylon bags containing GH were inserted into the rumen on d 1 and 2 of each collection period and incubated for 12, 24, 48 and 96 h to measure NDF and ADF degradation. Subsequently, steers were fed Yb-labeled GH and fecal samples were collected to determine particulate passage rate (PR). Dry matter and NDF intake, mean NDF and ADF in situ disappearance and ruminal VFA concentrations were greater (P less than .05) when CSM was fed; however, the delivery of CSM at various times did not affect (P greater than .10) these variables. Supplemented diets tended (P = .08) to have faster PR compared with the C diet. In the growth trial, CSM supplemented steers consumed more digestible DM (P less than .05) and had greater (P less than .05) daily gain compared with C steers. Effects due to time of CSM supplementation were not observed for the variables measured in the present study.

Postpartum reproductive performance in crude protein-restricted beef cows: return to estrus and conception.

A study was conducted to evaluate the effect of a deficiency in dietary crude protein intake on postpartum reproductive performance of first-calf beef cows. Forty primigravid Hereford heifers were randomly assigned to two groups that were fed isocaloric (100% NRC requirements) diets containing .96 (adequate) or .32 (deficient) kg crude protein per head daily. Animals were individually fed from 150 d prepartum to 40 d postpartum and then were group-fed until the end of the experiment at 110 d postpartum. Total nutrient intake was increased by 33% at time of parturition to meet lactation requirements. Animals were artificially inseminated between 45 and 110 d postpartum when they showed estrus. Eighty-nine percent of those fed adequate protein showed estrus, whereas only 63% of protein-restricted heifers exhibited estrus (P less than .05). First-service conception (P less than .05; 71 vs 25%) and overall pregnancy rates (P less than .05; 74 vs 32%) were lower in protein-restricted heifers. Compared with those fed adequately, protein-restricted heifers had a tendency for longer intervals to first estrus (P less than .08; 75 vs 86 d), to first service (P less than .09; 76 vs 87 d) and to conception (P less than .09; 81 vs 92 d). Regardless of diet, weight at first estrus, weight at first service and average daily gain to 40 d postpartum were negatively correlated (P less than .01) with length of intervals from parturition to first estrus and first service.(ABSTRACT TRUNCATED AT 250 WORDS)