title: Effect of whole-crop pea (Pisum sativum L.) silages differing in condensed tannin content as a substitute for grass silage and soybean meal on the performance, metabolism, and carcass characteristics of lambs.
abstract: Two experiments were conducted to investigate the effect of inclusion of whole-crop pea (WCP) silages, differing in condensed tannin content, as a substitute for grass silage (GS) and soybean meal on lamb metabolism, performance, plasma metabolites, digestibility, and carcass characteristics. In both experiments lambs were offered either solely GS or a 50:50 mix on a DM basis of GS with either low-tannin (LTPS) or high-tannin (HTPS) pea silage ad libitum. Each forage mix was fed with either 400 g/d of low-protein (LP) concentrate or 400 g/d of LP with an additional 200 g/d of pelletized soybean meal (HP), resulting in 6 dietary treatments. Experiment 1 examined the effects of the diets on metabolism, digestibility, and N balance using 6 lambs in 4 periods of 21 d in an incomplete crossover design. Experiment 2 used 48 lambs and examined the effects of the diets on ADG, plasma metabolites, and carcass characteristics over 56 d. Both experiments were analyzed using a 3 × 2 factorial arrangement of treatments. In Exp. 1, lambs offered the LTPS diets had a greater (P < 0.05) digestibility of DM and OM than those offered the GS diets. Lambs offered the WCP silages had an increased (P < 0.05) N intake, N output, and digestibility of GE compared with those offered GS. Mean N digestibility was greatest (P < 0.05) in lambs offered LTPS. Lambs offered HP diets had increased (P < 0.001) digestibility of DM, OM, GE and N, and N- intake, output, retention, and digestibility compared with those offered the LP diets. In Exp. 2, there was no effect (P > 0.05) of forage type on intake, slaughter BW, or feed conversion efficiency (FCE). However, lambs offered the LTPS had a greater (P < 0.05) ADG than those offered the GS diets. Feeding diets containing HP increased (P < 0.001) total DMI, slaughter BW, ADG, and FCE. Lambs offered the WCP had a greater (P < 0.05) plasma β-hydroxybutyrate and urea concentration compared with those offered the GS diets. Feeding lambs HP diets increased (P < 0.05) plasma urea and total protein. Forage mix had no effect (P > 0.05) on carcass composition except for fat depth, which was greater (P < 0.05) in lambs offered WCP silage. Diets containing the HP increased (P < 0.05) carcass weight, hind leg circumference, chop dimensions, and kidney weight. It was concluded that lambs offered LTPS performed better than those offered GS and that LTPS has a concentrate sparing effect. Additionally, the increased tannin concentration in HTPS did not increase performance over lambs offered either GS or LTPS.
authors.affiliation: Animal Science Research Centre, Harper Adams University College, Newport, Shropshire, TF10 8NB, United Kingdom.
authors.forename: K J
authors.initials: KJ
authors.lastname: Hart
authors.forename: L A
authors.initials: LA
authors.lastname: Sinclair
authors.forename: R G
authors.initials: RG
authors.lastname: Wilkinson
authors.forename: J A
authors.initials: JA
authors.lastname: Huntington
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000097:blood; D000818:Animals; D018592:Cross-Over Studies; D004063:Digestion / Q000502:physiology*; D004435:Eating / Q000502:physiology; D008297:Male; D008460:Meat / Q000592:standards*; D009584:Nitrogen / Q000097:blood / Q000378:metabolism*; D044945:Proanthocyanidins / Q000097:blood / Q000378:metabolism*; D012756:Sheep / Q000254:growth & development / Q000378:metabolism*; D012820:Silage; D014508:Urea / Q000097:blood
chemical_list: D044945:Proanthocyanidins; D014508:Urea; D009584:Nitrogen; D020155:3-Hydroxybutyric Acid