Steers grazing endophyte-free tall fescue: seasonal changes in nutrient quality, forage intake, digesta kinetics, ruminal fermentation, and serum hormones and metabolites.
摘要：
Six ruminally cannulated Holstein steers (average BW 514 kg) grazed a 33-ha, unirrigated, endophyte-free, () pasture from April 10 through December 7, 1989. Samples were collected in May, June, September, and November 1989. Total masticate N was relatively constant (P >.10) throughout the year. Masticate in vitro OM disappearance was less (P <.05) in September (48.4%) and November (50%) than in May (60.6%) and June (56%). Ruminal NH3N concentrations (milligrams/deciliter) were greater (P <.05) during May (20.5) and June (17.8) than during September (9.4) and November (5.9). Organic matter intake (grams/kilogram of BW) and particulate passage rate (percentage/hour) were least (P <.05) in November (15.3; 2.6) and not different (P >.10) during May (23.7; 3.1), June (20.7; 3.1), and September (21.0; 3.0). Extent and rate of and ruminal total VFA did not differ (P >.10) across sampling dates. Serum concentrations were not affected (P >.10) by sampling date, but serum N was greater (P <.05) during May and November than during June and September. Nonesterified fatty acid concentrations increased (P <.05) with advancing plant maturity. Serum concentrations were greater (P <.05) during May than during other sampling periods; however, concentrations were not altered (P >.10) by advancing plant maturity. Unirrigated fescue pasture maintained a high nutrient level throughout the grazing season, and masticate samples did not display the decrease in nutrient content often noted with other types of pasture forage.
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DOI：
10.1111/j.1439-0388.1993.tb00735.x
被引量：
年份：
1993
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