Effects of protein reduction in lamb fattening concentrate on in vivo digestibility, nitrogen balance and meat quality

Lobón, Sandra ; Baila, Clàudia ; Álvarez-Rodríguez, Javier (Universidad de Zaragoza) ; Blanco, Mireia ; Casasús, Isabel ; Pelegrin-Valls, Jonathan ; Joy, Margalida

Resumen: Determining the optimal crude protein (CP) content in light lambs’ diets is crucial for reducing ammonia. This study assessed lowering CP in fattening concentrates and its effect on digestibility and meat quality (two experiments). Two phases were tested: growing (14–19 kg BW; 18 % vs. 20 % CP) and finishing (19–25 kg BW; 17 % vs. 19 % CP). Experiment 1 involved 24 Rasa Aragonesa lambs, 12 per phase (growing: 14.0 ± 0.87 kg BW; finishing: 18.9 ± 0.78 kg BW, n = 6 per treatment) to assess apparent digestibility, nitrogen balance, and blood metabolites. The adaptation period to the diets were 12 days, while the collection period was 5 days. Digestibility was measured by total faecal collection and acid-insoluble ash (AIA) as internal marker. Experiment 2 evaluated meat quality of 24 Ripollesa lambs, slaughtered at 24.6 ± 0.23 kg BW after 42 days of fattening. Lower CP tended to decrease the acid detergent fibre (ADF) digestibility using total faecal method (P = 0.06) and decreased organic and dry matter digestibility with AIA (P = 0.03) during the growing phase (P < 0.05). No differences were observed in the finishing phase (P > 0.10). Digestibility coefficients were consistently underestimated with AIA compared to total faecal collection (P < 0.001). Nitrogen balance was unaffected by CP level (P > 0.05). Plasma metabolites were similar between treatments, except for β-hydroxybutyrate, which tended to be lower in Low CP lambs during the finishing (P = 0.09). Meat quality was minimally affected, however, Low CP increased metmyoglobin after 6 days of oxygen exposure (P = 0.005) and modified minor fatty acids. A moderate reduction of 2 % in dietary CP of light lambs appears feasible and does not impair nutrient digestibility and meat quality.

Idioma: Inglés

DOI: 10.1016/j.anifeedsci.2026.116670

Año: 2026

Publicado en: Animal Feed Science and Technology 334 (2026), 116670 [12 pp.]
ISSN: 0377-8401

Financiación: info:eu-repo/grantAgreement/ES/DGA/A25-23R
Financiación: info:eu-repo/grantAgreement/ES/INIA/RTA2017-00008-C02
Financiación: info:eu-repo/grantAgreement/ES/MINECO/PRE2018-086670

Tipo y forma: Artículo (Versión definitiva)

Área (Departamento): Área Producción Animal (Dpto. Produc.Animal Cienc.Ali.)