Impact of carob (Ceratonia siliqua L.) pulp inclusion and warm season on gastrointestinal morphological parameters, immune-redox defences and coccidiosis in concentrate-fed light lambs.

This study aimed to evaluate the effects of dietary carob (Ceratonia siliqua L.) pulp and warm season on gastrointestinal morphological parameters, immune-redox defences and coccidiosis in concentrate-fed light lambs. Weaned lambs were assigned to one of three concentrate-based diets: C0 (without carob pulp), C15 (150 g/kg of carob pulp) and C30 (300 g/kg of carob pulp) from 40 to 80 days of age in two consecutive cold and warm batches. Blood samples were collected at Day 80 to determine the metabolic status. Rectal faeces were sampled at Days 50, 65 and 80 to determine consistency and oocyst count per gram. Inclusion of carob pulp in lamb diets did not affect lamb growth but reduced coccidia oocyst excretion, improved faecal consistency and gastrointestinal morphological parameters, enhancing the ruminal thickness of the papilla living strata and reducing the darkness of the epithelium colour. Moreover, carob condensed tannins in the lambs' diet enhanced the expression of antioxidant SOD2 in rumen, while down-regulated NRF2, SOD1, CAT and PPARG in ileum. There was no interaction between the treatments and season in the evaluated variables. Lambs from the warm season exhibited reduced growth performance, altered ruminal epithelium, lower circulating iron levels, increased protein concentrations and higher coccidiosis susceptibility. In addition, regulatory immune and antioxidant mechanisms to counterbalance reactive oxygen species production in gastrointestinal tissues were evident. Dietary inclusion of carob pulp (150 and 300 g/kg) in lamb diets improved gastrointestinal health and homeostasis but did not ameliorate the deleterious effects of warm season.

Minimum Effects of Sampling Time on the Apparent Digestibility of Nutrients and Blood Protein Catabolites in Light Lambs.

This experiment aimed to evaluate the effects of sampling time on organic matter (OM), crude protein (CP) and phosphorous (P) apparent digestibility and plasma urea and creatinine concentration in growing and finishing male Ripollesa lambs fed different CP concentrations in the diet. Twenty-four male Ripollesa lambs with 14.5 kg body weight (BW) were randomly assigned to two groups differing in CP content in the growing (14 to 19 kg of BW) and finishing (19 to 25 kg of BW) phases (20% vs. 18% CP and 19% vs. 17% CP, respectively). Faeces collected from the rectum and blood samples collected from the jugular vein were taken at 8:00 a.m., 12:00 p.m., and 4:00 p.m. During the growing period, the OM, CP and P apparent digestibility were higher in the lower CP diet (p < 0.05), but only P was affected by the sampling time, being highest at 8:00 a.m. (p < 0.05) compared to other sampling hours. During the finishing period, there were no differences in these digestibility coefficients between diets or sampling times (p > 0.05). Sampling time did not affect (p > 0.05) plasma urea concentrations either in the growing or finishing period. Plasma creatinine concentrations did not differ (p > 0.05) between lambs receiving 18% or 20% CP diets, but during the finishing period, it was lower at 4:00 p.m. in lambs fed 17% CP (p < 0.05) than those offered 19% CP. Overall, the results suggest that the collection schedule to evaluate the protein nutritional status can be shortened through one spot sample of faeces or blood in the morning.

Effect of Dietary Crude Protein on Productive Efficiency, Nutrient Digestibility, Blood Metabolites and Gastrointestinal Immune Markers in Light Lambs.

This study hypothesized that reducing the level of crude protein (CP) in lambs' feed may improve nutrient utilization and did not negatively affect their productive efficiency, blood metabolites, oxidative status (OS) or intestinal immune barrier function. A total of 120 weaned male Ripollesa lambs (45-60 days old and 15.0 ± 1.5 kg of body weight) were used. Four feed concentrates were formulated for two different phases (growing and finishing): CP20/19 group (20% and 19% of CP on dry matter basis, for each phase, respectively) and CP18/17 group (18% and 17% of CP on dry matter basis, for each phase, respectively). Lambs were randomly assigned to feeding treatments by balancing initial body weight between groups. The reduction of dietary CP level did not impair their growth performance parameters, while it did improve the apparent digestibility of organic matter. Furthermore, the lambs of the CP18/17 group showed lower plasma urea levels with no effect on OS (malondialdehyde levels) or gastrointestinal immunity markers (gene expression of interleukin 10 (IL10), tumor necrosis factor-α (TNFA) and transforming growth factor-ß1 (TGFB)).