Intake, in vivo digestibility and protein utilization of wethers fed timothy or tall fescue when harvested at different dates in the first regrowth cycle
IF 2.5 2区 农林科学Q1 AGRICULTURE, DAIRY & ANIMAL SCIENCE
Dannylo Sousa , Ronald Hatfield , Wolfram Richardt , Elisabet Nadeau
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引用次数: 0
Abstract
The objective of this study was to evaluate the effects of harvest date in the first regrowth cycle and grass species on intake, in vivo digestibility and its relation to protein utilization in wethers fed timothy or tall fescue silages. Timothy and tall fescue were harvested at regular (RTI and RTF, respectively) or late date (LTI and LTF, respectively) in the first regrowth, creating four experimental silages. Eight wethers were used in a duplicated 4 × 4 Latin square. Experimental periods lasted for 4 wk and wethers were fed ad libitum during the first 3 wk, with intake recorded during the third week. During the fourth week, wethers were fed 80% of ad libitum, and feces and urine were collected during the last 4 d. Wethers receiving RTI showed the greatest DM intake when expressed as kg/d or as percentage of body weight (BW) (P≤0.05). The intake of neutral detergent fiber (aNDFom) was affected by forage species only, where animals fed timothy silages had greater aNDFom intake than animals fed tall fescue silages (P<0.001). Intakes of CP and sum of the protein fractions A, B1 and B2 (AB1B2) were affected by the interaction between harvest date and forage species, where wethers fed RTI showed the greatest intakes of CP (P=0.001) and AB1B2 (P=0.02). Harvesting the forages at late date decreased the in vivo digestibility in wethers but only for timothy, where animals fed LTI silage showed the lowest DM (P<0.001), organic matter (OM) (P<0.001), aNDFom (P=0.02) and acid detergent fiber (P=0.004) digestibility, and a tendency for lower CP digestibility (P=0.07) compared with the other silages. Wethers fed RTI silage showed greater intake of nitrogen (N) (P=0.001) and digestible OM (P=0.003), greater allantoin (P=0.03) and hippuric acid (P=0.05) excretions, greater microbial N flow (P=0.03), and a tendency for greater excretion of fecal N (P=0.09) compared with the other silage-fed animals. In conclusion, delayed harvest decreased in vivo digestibility only in timothy, but even with lower in vivo digestibility wethers fed timothy silages showed a greater intake than wethers fed tall fescue silages, likely due to lower concentration of hydroxycinnamic acids observed in timothy compared with tall fescue as published previously.
期刊介绍:
Animal Feed Science and Technology is a unique journal publishing scientific papers of international interest focusing on animal feeds and their feeding.
Papers describing research on feed for ruminants and non-ruminants, including poultry, horses, companion animals and aquatic animals, are welcome.
The journal covers the following areas:
Nutritive value of feeds (e.g., assessment, improvement)
Methods of conserving and processing feeds that affect their nutritional value
Agronomic and climatic factors influencing the nutritive value of feeds
Utilization of feeds and the improvement of such
Metabolic, production, reproduction and health responses, as well as potential environmental impacts, of diet inputs and feed technologies (e.g., feeds, feed additives, feed components, mycotoxins)
Mathematical models relating directly to animal-feed interactions
Analytical and experimental methods for feed evaluation
Environmental impacts of feed technologies in animal production.