Evaluation Of Yield And Quality Of Four Common Vetch Varieties And Their Effects On Lamb Fattening And Methane Emission

Common vetch（Vicia sativa L.）is an annual grown crop for livestock feed and soil fertility improvement.It plays an important role in the regulation of planting structure and development of grassland agriculture.Previous studies on this crop have either focused on cultivation patterns or on the effects of feeding livestock.In this study,the“forage-sheep-methane emission”research route was used as the main clue,and four varieties of common vetch such as Lanjian 1,Lanjian 2,Lanjian 3 and 333A were used as the tested materials.In a four-year study,the yield and quality of forages and seeds of the tested varieties,fattening effect of feeding Hu lambs and methane emission levels were systematically evaluated,which provides a scientific basis for the cultivation and utilization of common vetch.The concrete result obtained are as follows:1.Yield of hay and seedIn the Xiahe County,Gannan Tibetan Autonomous Prefecture,Gansu Province,field experiments for two consecutive years showed that hay yield increased gradually with plant growth and development.Hay yield at flowering stage ranged from 2.37 to3.56 t dry matter（DM）ha^-1.The hay yield was greatest（P<0.05）in Lanjian No.1(3.56 t DM ha^-1),intermediate in Lanjian No.2(3.33 t DM ha^-1)and 333A(3.11 t DM ha^-1),and least in Lanjian No.3(2.74 t DM ha^-1).The seed yields among the varieties ranged from 1021 to 1491 kg DM ha^-1.The seed yield was greatest（P<0.05）in Lanjian No.3(1491 kg DM ha^-1)and Lanjian No.2(1403 kg DM ha^-1),intermediate in Lanjian No.1(1146 kg DM ha^-1),and least in 333A(1021 kg DM ha^-1).2.Nutrient composition of hay and seedThe nutrient content of hay and seed harvested in result 1 was determined by conventional nutrient analysis method.The results showed that hay crude protein（CP）content at flowering stage varied from 21.6 to 23.2%DM among the varietes,and was the greatest（P<0.05）in Lanjian No.3 and Lanjian No.2（23.2 and 22.9%DM,respectively）.The CP content among the seeds of the varieties ranged from 35.3 to37.0%DM.The seed CP content was greatest（P<0.001）in 333A（37.0%DM）,intermediate in Lanjian No.1(36.0%DM,and least in Lanjian No.2（35.4%DM）and Lanjian No.3（35.3%DM）.Integrated hay yied and CP content,hay CP yield at the flowering stage varied from 549 to 770 kg ha^-11 among the four varieties,and was the greatest（P<0.05）in Lanjian No.1(770 kg ha^-1).3.In vitro digestibility of hay and intestinal digestibility of seed crude proteinThe in vitro digestibility of hay and the in vitro small intestine protein digestibility of seed were determined by using rumen fluid method and modified3-step in vitro procedure,respectively.The results showed that in vitro DM digestibility of hay among varieties ranged from 70.1 to 92.0%DM during the the growth stage with the lowest being observed at mature stage.In vitro DM digestibility of hay at flowering stage among the varieties ranged from 81.4 to 83.8%DM,and was not significantly（P>0.05）by varieties.Intestinally absorbable digestible protein of the seeds of the varieties ranged from 14.4 to 20.3%CP,and were the greatest（P<0.001）in 333A（20.3%CP）and Lanjian No.1（19.4%CP）.4.Feeding effect of hay on lambThe fattening effect of the tested forages on 3-month-old Hu lambs was evaluated by adding the four varieties of common vetch,at the quantity of 20%of the diet,to the diet,with the same proportion of alfalfa hay as control.The results showed that the lambs fed with Lanjian No.3 and Lanjian No.2 hay diets at flowing stage had the greater（P<0.05）average daily gain（ADG）which increased by 23.4%to 27.7%,compared with the control diet,while ADG of lambs fed 333A and Lanjian No.1diets were similar（P>0.05）to that of the control diet.The feeding effect of common vetch hay at mature stage was lower than that of hay at flowering stage.The ADG of the lambs fed 333A and Lanjian No.3 hay diets at mature stage decreased by 19.0%to 20.6%（P<0.05）compared with the control diet,while the ADG of Lanjian No.1and Lanjian No.2 hay diets at mature stage had no significant（P>0.05）difference than that of the control diet.The lambs fed Lanjian No.3 and Lanjian No.2 hay diets at flowing stage had the greater（P<0.05）apparent digestibility of CP and neutral detergent fiber（NDF）which increased by 14.2%to 14.5%and 20.2%to 20.6%,respectively,compared with the control diet,while apparent digestibility of CP and NDF of lambs fed 333A and Lanjian No.1 hay diets were similar（P>0.05）to that of the control diet.Apparent digestibility of CP and NDF of lambs fed the hay diets at mature stage were lower than that of lambs fed hay diets at flowering stage.The lambs fed Lanjian No.1 and Lanjian No.2 hay diets at mature stage had similar（P>0.05）apparent digestibility of CP and NDF compared with the control diet,while apparent NDF digestibility was lesser（P<0.05）in 333A and Lanjian No.3 hay diets than in the control diet which was reduced by 21.0%to 22.6%.5.In vitro and in vivo methane emission of sheep fed with common vetch hayWith the diet ratio of the result 4,Dorper×thin tailed Han adult sheep were used as the test livestock,and the in vitro methane yield of diets and the methane emission of mutton sheep were measured by in vitro gas production method and gas metabolism experiment,respectively.The results showed that in vitro methane emission of the hay diets at flowing stage,expressed in mL g^-11 of organic matter（OM）after 12,24,and 48 h of incubation,ranged from 28.1 to 34.0 mL g^-1,42.1 to 49.0 mL g^-11 and 49.4 to 56.3 mL g^-1,respectively,and were not significantly（P>0.05）different among the four hay diets.In vitro CH₄ emission of the hay diets at mature stage was lower than that of the hay diets at flowering stage.In vitro CH₄ emission of the hay diets at mature stage,expressed in mL g^-11 of OM after 12,24,and 48 h of incubation,ranged from 23.0 to 27.9 mL g^-1,36.4 to 41.3 mL g^-11 and 43.3 to 48.8 mL g^-1,respectively.There was significant difference in 12-h in vitro CH₄ expressed in mL g^-1of OM among the hay diets at mature stage,which was greatest（P<0.05）for Lanjian No.1 hay diet(27.9 mL g^-1).In vitro CH₄ emission of the hay diets at mature stage,expressed in mL g^-11 of OM after 24,and 48 h of incubation,were similar（P>0.05）among the four hay diets.In vivo methane emission expressed per unit of day or per unit of OM digested of lambs fed the diets at flowering stage ranged from 50.7 to 55.5 L day^-11 and 53.0 to56.5 L kg^-1,respectively,and were not significantly different（P>0.05）among the four hay diets.Daily methane emission of lambs fed the hay diets at mature stage was lower than that of hay diets at flowering stage,while methane emission expressed per unit of OM digested of lambs fed the hay diets at mature stage were higher that of hay diets at flowering stage.In vivo methane emission expressed per unit of day or per unit of OM digested of lambs fed the hay diets at mature stage ranged from 46.1 to50.0 L day^-11 and 57.9 L kg^-11 to 63.4 L kg^-1,respectively,and were not significantly different（P>0.05）among the four hay dietsIn summary,of the varieties tested,Lanjian 1 had the greatest hay yields,and Lanjian 3 and Lanjian 2 had the greatest seed yields.Common vetch is a crop with high feeding value.The feeding effect of common vetch hay at flowering stage was greater than that of hay at mature stage.The feeding effect of Lanjian No.2 and Lanjian No.3 hay at flowering stage was greater than that of alfalfa hay,respectively.The feeding effect of Lanjian No.1 and Lanjian No.2 hay at mature stage was similar to that of alfalfa hay,respectively.The recommended planting varieties of common vetch Lanjian No.2,followed by Lanjian No.1,333A and Lanjian No.3,as indicated by above measurement indexes.