Rumen fermentation and metabolic profile of rams fed with diets amended cottonseed cake

The aim of the study was to evaluate the addition of increasing cottonseed cake contents in the diet. The diets were composed of corn silage (500 g kg^-1) and concentrate feed (500 g kg^-1) on a dry matter (DM) basis. The treatments consisted of the substitution of 0, 140, 280, and 420 g kg^-1 soybean meal to cottonseed cake in the DM of concentrate feed. Four rams of the Santa Inês breed, average age of 12 months and average weight of 27.77 ± 3.87 kg, were distributed in a Latin square design (4 × 4) in a split-split-plot design, with diets in the plots and as subplots were 5 days of collection and the collection times. The results were subjected to analysis of variance and regression at 5% probability. The soybean meal substitution contents by cottonseed cake in the concentrate increased linearly the pH (P = 0.019). Ruminal ammonia-nitrogen concentration decreased linearly by 0.0137 mg dL^-1 at each 10 g/kg of substitution and the time after feeding promoted the same effect (P < 0.001) decreased linearly by 0.6204 mg dL^-1 at each hour after feeding. There was an increased linearly of 0.0116 mmol mL^-1 at the concentration of propionic (P = 0.008) and a reduction of 0.0062 mmol mL^-1 at the concentration of butyric (P = 0.009) with cottonseed cake content; however, the substitution did not influence the others short-chain fatty acids. Replacement of soybean meal with cottonseed cake in the sheep feed did not significantly alter the blood parameters, promoting minor changes in the ruminal parameters mainly in the ruminal ammonia-nitrogen without affecting the animal's health.