Crude protein and condensed tannins in lamb diets: productivity, metabolic status and gastrointestinal immune and antioxidant response
- Autores: Jonathan Pelegrin Valls
- Directores de la Tesis: Beatriz Serrano Pérez (dir. tes.), Javier Álvarez Rodríguez (dir. tes.)
- Lectura: En la Universitat de Lleida ( España ) en 2023
- Idioma: español
- Tribunal Calificador de la Tesis: Beatriz Soret Lafraya (presid.), Isabel Blanco Penedo (secret.), María Ángeles Latorre Górriz (voc.)
- Programa de doctorado: Programa de Doctorado en Ciencia y Tecnología Agraria y Alimentaria por la Universidad de Lleida
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
This doctoral thesis was designed to evaluate the effects of crude protein reduction and the inclusion of carob pulp (as a source of condensed tannins) in the diet of intensive fattening light lambs, as well as to understand the impact of fresh sainfoin (also a source of condensed tannins) in the diet of ewes on the gastrointestinal health of suckling lambs. For this purpose, three trials were conducted to study the productivity, the nutritional metabolism, and the immune and antioxidant responses in the gastrointestinal tract.
Firstly, a 2% reduction of crude protein in the growing (20% vs. 18%) and finishing (19% vs. 17%) phases of lambs were studied, observing that this reduction did not affect the productive performance or protein metabolism. Furthermore, it did not affect the intestinal antioxidant and immune response balance, and improved the apparent digestibility of organic matter and phosphorus. Evaluation of sampling at different times of the day did not show interaction between crude protein level and sampling time on digestibility of organic matter, crude protein or phosphorus, nor in plasma urea or creatinine. However, during the growing phase, differences between diets in protein digestibility at 08:00 a.m. were found.
Secondly, an inclusion of 150 g/kg and 300 g/kg of carob pulp in the lamb did not impact on animal productivity, energy and protein metabolism, although the highest level of inclusion decreased nutrient digestibility and increased the feed conversion ratio. On the other hand, the inclusion of carob pulp improved rumen health by reducing keratinisation, increasing the thickness of the living layers of the rumen papillae and increasing free radical scavenging enzymes. In addition, there was a coccidiostatic effect by reducing faecal oocyst excretion and regulating the gastrointestinal immune-antioxidant response. However, under heat stress, the inclusion of carob pulp would not have enough influence to generate a positive adaptive antioxidant status. In this regard, the warm season had a negative impact on productivity, metabolic status (total protein and iron), rumen histological parameters and coccidial infection. The anti-inflammatory and antioxidant response was increased in warm season lambs, which demonstrated a modulation of the pro-inflammatory and oxidative effects associated to heat stress.
Thirdly, the inclusion of sainfoin in dams' diets promoted a reduction of coccidial oocysts in faeces, but had no negative effects on histopathological analyses of the jejunum and ileum. Condensed tannin activity was associated to decreased immune response and antioxidant enzymes in the jejunum, probably because of its ability to scavenge free radicals, whereas in the ileum it increased antioxidant enzyme expression involved in hydrogen peroxide degradation.