Effect of the Concentrate Feed on in vitro Gas Production and Methane in Sicilo-Sarde Sheep

The addition of concentrates of different types (cereals, maize and white sorghum) in the diet of dairy sheep leads to changes in rumen parameters and the end products of digestion in particular the total gas production. The objective of the present work was the determination of total gas and methane production (CH4) in the rumen of Sicilo Sarde rams supplemented by different types of concentrates. Four SiciloSarde rams of 4.8 years ±0.5 of age with an average live weight of 45.25±3.5 kg, fitted with permanent canulas and housed in individual cages were used in the trial. They received a daily ration distributed in two equal meals. The ration included 1.5 kg DM of oat hay and was supplemented by one of four concentrates: CC (10% barley, 43.3% corn, 25% wheat bran, 17.7% soybean meal, 4% sheep VMC, CS (66% white sorghum, 30% faba, 4% sheep VMC); CT (71% triticale, 18% faba, 7%, soybean meal, 4% sheep CMV) or CO (71.5% barley, faba 17.5%, 7% soybean meal and 4% sheep VMC). Total gas (CO2 and CH4) was determined on rumen content filtered through four layers of surgical gas, collected before the distribution of the morning meal. Animals were deprived from water the night before sampling. In plastic syringes of 100 ml each, we put 0.5 g of substrate (oat hay crushed at 1 mm), 10 ml of rumen fluid and 40 ml of artificial saliva. Then, the content of each syringe was bubbled with CO2 to eliminate oxygen and were then locked up by a piston lubricated with Vaseline. Syringes were then placed vertically in a water bath at 39°C. The total volume of gas after 36 hours incubation was different (p <0.05) among diets, the CO concentrate showed the highest value 87.00±17.29 ml while the lowest value was found in the CT concentrate (56.58±13.06 ml). Intermediate productions were observed for DC and CS concentrates with no significant differences between them (p> 0.05). The CH4 production in the rumen was 24.91±5.69 ml representing 28.6% for the CO concentrate significantly different (p < 0.05) from 19.75±3.88 ml or 34.9% of total gas production for the CT concentrates. Quantities produced by the CC and CS were similar (22.08±4.18 vs. 21.16±3.21). Models of the kinetics of gas production are as follows: CC: Y= 58.7 * (1e ); 0.001*t CS: Y= 50.3 * (1e ); 0.002*t CT: Y= 48.1 * (1e ); and 0.002*t CO: Y= 34.5 * (1e) 0.003*t