Effects Of Replacement Of Corn With Alfalfa Hay And Beet Pulp On The Performances And Rumen Function Of Lambs

Young ruminants have a great demand for energy in the rapid growth stage,solid concentrate feeding can meet the requirements of the body growth and stimulate the growth and differentiation of rumen epithelium.However,the solid concentrate feeding may also reduce the ruminal pH and cause the occurrence of rumen plaques,resulting in the insufficiency of keratinization of the rumen epithelium.The intake of roughage can decrease the risk of rumen plaque,change the rumen fermentation pattern,and promote the establishment of rumen flora,which is essential for the healthy growth of ruminants.In the present study,we intends to replace corn with alfalfa hay or beet pulp to study the effects on lamb growth and fattening performance,rumen function and muscle fatty acid.In this study,75 newborn male Hu lambs were equally divided into 3 treatments.These treatments were control diet?45% corn?,alfalfa hay diet?10% alfalfa hay+35% corn?and beet pulp diet?10% beet pulp+35% corn?.All lambs were breast-fed with the ewes,and supplemented with the starter on the 3th day.All lambs were weaned on the 35 th day,housed in individual pens and continued to feed for 77 days.On days 50 of feeding study,five lambs per treatment were randomly selected for digestive metabolism trials.The test lasted for 7 days,which the first 3 days was adaptation period.The fecal and feed samples were collected continuously for follow-up 4 days to determine the apparent digestibility of each nutrient.At the end of feeding,ten lambs with similar body weight were selected for slaughter test in each group to determine the slaughter performance of the lambs.Samples of rumen fluid were collected to analyze the composition of VFA and microflora in the rumen.Samples of the longissimus dorsi were obtained to determine the composition of long-chain fatty acids in muscle.The results are as follows:1.The average daily gain and average daily feed intake of lambs for alfalfa hay and beet pulp groups were significantly higher than those of the control group during 1-35 d,36-84 d,1-84 d?P<0.05?,respectively.The feed conversion ratio of the alfalfa hay group was significantly higher than that of the control and beet pulp groups?P<0.05?.No differences were observed in body height,oblique length,bust and pipe circumference among the treatments?P>0.05?.The apparent DM digestibility of the alfalfa hay group was significantly lower?P<0.05?than that of other groops.The apparent digestibility of OM and NDF of the the alfalfa hay group were significantly lower than those of the control group but similar to the beet pulp group.There were no differences for weight and slaughter rate of lambs among the alfalfa hay and beet pulp groups.The beet pulp group had significantly higher weight of net stomach and lower weight of abomasum compared to the alfalfa hay group?P<0.05?.2.The proportions of acetate,isobuyrate and isovalerate in the rumen of the alfalfa hay group were significantly higher than those of the beet pulp group?P<0.05?.The alfalfa hay group had significantly lower propionate proportion and higher ratio of acetate to propionate compare to other groups?P<0.05?.The proportion of valerate in the beet pulp group was significantly higher than that in the control group and the alfalfa hay group?P<0.05?.The amount of ruminococcus albus in the rumen of the alfalfa hay group was significantly higher than that of the beet pulp group?P<0.05?.The amount of streptococcus bovis was higher in control group than in beet pulp group?P=0.075?.3.The rumen flora of the alfalfa hay group had the highest degree of richness and diversity,and the similarity of the rumen flora for each group was very low.The bacteroidetes,firmicutes and proteobacteria in the rumen were the dominant bacteria among the three groups.The beet pulp group had significantly?P<0.05?higher relative abundance of the firmicutes and lower relative abundance of the proteobacteria compared to the control group.The relative abundance of the fibrobacteres in the alfalfa hay group was significantly higher than that in the beet pulp group?P<0.05?.The relative abundance of the spirochaetae was significantly higher in the alfalfa hay group than in ther other groups?P<0.05?.The relative abundance of succinivibrionaceae in the control group was significantly higher than that in the beet pulp group?P<0.05?.The relative abundance of the lachnospiraceae was significantly lower in the control group than in the alfalfa hay group and the beet pulp group?P<0.05?.The relative abundance of prevotella₇ was significantly higher in the beet pulp group than in the alfalfa hay group?P<0.05?.The succinivibrio was significantly lower in beet pulp group than in the control group?P<0.05?.The lightness,redness and yellowness of the rumen wall in the alfalfa hay group were significantly higher than those of the control group and the beet pulp group?P<0.05?.The rumen papillae length of the control group and the alfalfa hay group was significantly higher than that of the beet pulp group?P<0.05?.4.The proportion of C15:0 in the muscle of the control group was significantly higher than that of the alfalfa hay group and the beet pulp group?P<0.05?.The proportion of C17:0?P<0.05?was the highest for control group,lowest for alfalfa hay group and internedediate for beet pulp group.The ratio of trans C18:1 in the control group and the beet pulp group were significantly higher than that in the alfalfa hay group?P<0.05?.The ratio of C18:2 n-6t in the alfalfa hay group was significantly higher than that in the control group?P<0.05?.In conclusion,addition of alfalfa hay and beet pulp seemed to improve production performance of the lamb after weaning by increasing feed intake and body weight of the lambs.Replacing corn with alfalfa hay can increase the proportion of acetate,and reduce the proportion of propionic acid,promote the richness and diversity of rumen bacteria,the number of cellulolytic bacteria,and improved rumen functions.