Effects Of Feeding Pelleted Complete Feed On Growth Performance,Digestion And Meat Quality Of Fattening Lambs

The demand of consumers for lamb is increasingly growing with improved living standards,and thus lamb production and per capita consumption have been increasing each year.With the progress of animal nutrition technology,fattening lamb farming has shifted from traditional feeding to total mixed rations(TMR),and now is further moving to pelleted feed.Animals have an instinct to select a feed from different physical forms,which can be utilized in animal production by manufacturing feed with a particular physical form.A large number of experiments on feed physical form have been reported in swine and poultry but few in fattening lambs.Do fattening lambs differ in the effects of feed physical form on performance and meat quality? To answer the question,two experiments with lambs at different ages were conducted to evaluate the effects of feeding pelleted complete feed on growth performance,digestion and meat quality in comparison with powder feed.Experiment 1: Sixteen fattening lambs at the age of three months and the body weight of 24.7 ± 1.9 kg were randomly assigned to two groups and arranged in a completely randomized design to investigate effects of feeding a pelleted complete feed on growth performance,rumen fermentation characteristic and meat quality of lambs.Dietary treatments were pelleted feed and powder feed with the same diet composition.During a 67-d fattening period,growth performance were measured and samples of blood and rumen fluid were collected.Then a 11-day period was followed with 4 d for adaptation and 7 d for digestibility measurements.At the end of the fattening period,lambs were slaughtered,digestive tracts and meat were collected and evaluated.Pelleted feed increased average feed intake and average daily gain(P < 0.01)of lambs,decreased feed conversion rate and apparent digestibility of dry matter,but did not change apparent digestibilities of crude protein,acid detergent fiber,ether extract,and neutral detergent fiber.Feeding powder feed increased ash and crude protein contents of orts(P < 0.01)and decreased neutral detergent fiber content(P < 0.05).Feeding pelleted feed altered rumen fermentation and increased total short chain fatty acids in rumen fluid before morning feeding(P < 0.05)and decreased pH value of rumen fluid 3 h after morning feeding.Furthermore,feeding pelleted feed increased slaughter and carcass weights(P < 0.05),significantly increased liver and lung weights(P < 0.01)and decreased organ indexes(P < 0.05).Feeding pelleted feed did notsignificantly affect meat quality of fattening lambs(P > 0.05).Feeding pelleted feed significantly increased incomes from fattening lamb farming(P < 0.01).Experiment 2: Sixteen fattening lambs at the age of five months and the body weight of43.8 ± 4.0 kg were randomly assigned to two groups with a completely randomized design to investigate effects of feeding a pelleted complete feed on growth performance,rumen fermentation characteristic and meat quality of lambs.Dietary treatments were the same as the Experiment 1.During the 24-d fattening period,growth performance and digestibility were measured.At the end of the fattening period,lambs were slaughtered,samples of digestive tracts and meat were collected and evaluated.Feed pelleting increased average feed intake(P < 0.01)of lambs,but decreased feed conversion rate.Feeding pelleted feed altered rumen fermentation,increased the concentrations of total short chain fatty acids and ammonia in rumen fluid(P < 0.05),increased the ratio of acetate to propionate(P < 0.05),decreased ruminal pH value(P < 0.01)before morning feeding.Feeding pelleted feed increased the ratio of acetate to propionate(P < 0.01)and decreased ruminal pH value(P < 0.01)3 h after morning feeding.Feeding pelleted feed did not significantly affect organ weights,organ indexes and meat quality of fattening lambs(P >0.05).Furthermore,feeding pelleted feed increased slaughter and carcass weights(P < 0.05),significantly increased liver and lung weights(P < 0.01)and decreased organ indexes(P <0.05).Feeding pelleted feed did not significantly affect meat quality of fattening lambs(P >0.05).Feeding pelleted feed significantly increased incomes of fattening lambs(P < 0.01).In conclusion,feed pelleting improved growth performance of fattening lambs,promoted rumen fermentation,did not alter meat quality,and increased incomes of fattening lambs.