Abstract
The objective of this study was to evaluate nutrient intake, in vivo digestibility, and in situ degradability of different cultivars of hay (i.e., [Jiggs] and [Tifton-85] bermuda grass (Cynodon spp.) and [alfalfa] (Medicago sativa) and [stylo] Campo Grande (Stylosanthes sp.)) and nitrogen balance in sheep. We used eight rumen-cannulated F1 Santa Ines × Dorper castrated male sheep with body weights of 35.0 kg in a double 4 × 4 Latin Square experimental design. The intake and total apparent digestibility of nutrients were higher (P<0.05) for alfalfa than for stylo hay. The in vivo dry matter (DM) digestibility of Jiggs (47.6%), Tifton-85 (53.4%), stylo (29.3%), and alfalfa (53.2%) hays and in situ DM degradability were equivalent in the range of 7.6 to 63.2 h of degradation. The in vivo neutral detergent fiber (NDFap) digestibility of Jiggs (53.7%), Tifton-85 (64.4%), stylo (42.2%), alfalfa (56.2%), and in situ NDFap degradability were equivalent from 37.3 h. Nitrogen balance was negative only in animals fed stylo hay. Alfalfa hay provides a higher nutrient intake than other hays. The alfalfa and bermuda grass hays used in sheep diets presented better digestibility than stylo hay. The results are suitable to predict in vivo digestibility from in situ degradability parameters.
Highlights
The optimal utilization of diets by ruminants is influenced by the chemical composition and physical characteristics of the feed (Kammes et al, 2012)
The alfalfa and bermuda grass hays used in sheep diets presented better digestibility than stylo hay
DM, dry matter; OM, organic matter; CP, crude protein; EE, ether extract; NDFap, neutral detergent fiber corrected for ash and protein; NFC, non-fiber carbohydrates; ADF, acid detergent fiber; iADF, indigestible acid detergent fiber; iNDF, indigestible neutral detergent fiber; LIG, lignin
Summary
The optimal utilization of diets by ruminants is influenced by the chemical composition and physical characteristics of the feed (Kammes et al, 2012). According to Kammes and Allen (2012), the passage of digesta from the rumen is a dynamic process that is affected by numerous feed and animal factors. These authors observed that when using alfalfa silage or orchard grass silage as the only source of forage, the selective retention of small particles was less for legumes than for grass, resulting in lower rumen fill and less effective fiber. According to Olivo et al (2017), techniques such as in vivo tests are the most accurate methods for determining the nutritional value of feeds used in animal diets, but they are more expensive. Alternative methods, such as in situ degradability tests, have been used in several studies in the field of animal nutrition (Chaudhry & Mohamed, 2011; Krizsan et al, 2013; Benninghoff et al, 2015) to evaluate the kinetics of ruminal degradation of several feeds used in diets
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