酵母培养物对羊生长性能和胴体特性的影响

Animal Feed Science and Technology142(2008)33–43Available online at Growth performance and carcass characteristics of Awassi lambs and Shami goat kids fed yeastculture in theirfinishing dietH.H.Titi a,∗,R.O.Dmour a,A.Y.Abdullah ba Department of Animal Production,Faculty of Agriculture,University of Jordan,Amman11942,Jordanb Department of Animal Production,Faculty of Agriculture,Jordan University of Science and Technology,P.O.Box3030,Irbid22110,JordanReceived25January2007;received in revised form18June2007;accepted25June2007AbstractTwo experiments were completed to examine effects of inclusion of a yeast culture(YC)to a diet based on barley grain and wheat straw on digestibility,growth and meat traits of Awassi lambs and Shami goat kids.Experiment1studied effects of YC on apparent digestibility of dry matter (DM),organic matter(OM),crude protein(CP),neutral detergentfiber(NDF),acid detergentfiber (ADF)and N balance in sheep,while experiment2studied effects on growth performance and carcass composition of lambs and kids.The same diet was used in both experiments and the YC was added to the diet of treated groups at the level of12.6kg YC/tonne of diet.Addition of YC had no effect on apparent digestibility of DM,CP and NDF,but it increased(P<0.05)digestibility of OM and ADF. No differences occurred in N intake,output or retention.Addition of YC did not affect growth rate, or DM intake,in both lambs and kids.YC supplementation to lambs reduced hot carcass weight,cold dressing proportion and total muscle/bone ratio,but increased empty digestive tract weight.There were no changes in back fat thickness,intermuscular fat of the leg muscle,and weights and proportions of carcass cuts.Measures of kids’carcass characteristics and quality also did not differ.Only cuts of leg and shoulder differed(P<0.05)when calculated as a proportion of the whole carcass cut.Results show that YC supplementation increased digestibility with no effect on growth,feed intake or feedAbbreviations:ADF,acid detergentfiber;ADG,average daily gain;DM,dry matter;FCR,feed conversion ratio;LW,live weight;NDF,neutral detergentfiber;OM,organic matter;YC,yeast culture∗Corresponding author.E-mail address:htiti@.jo(H.H.Titi).0377-8401/$–see front matter©2007Published by Elsevier B.V.doi:10.1016/j.anifeedsci.2007.06.03434H.H.Titi et al./Animal Feed Science and Technology142(2008)33–43conversion ratio of fattening lambs and kids.However,YC supplementation reduced meat/bone ratio and tissue protein content,but increased fat content in carcasses of fattening Awassi lambs,but not in fattened Shami kids.©2007Published by Elsevier B.V.Keywords:Yeast;Digestibility;Growth performance;Carcass;Lambs;Kids1.IntroductionFeed is a major component of livestock farming and many experiments have been com-pleted to improve the nutritive value of low quality feeds utilized by ruminants.Utilization efficiency of somefibrous feedstuffs might be improved through utilization of biotech-nology,such as yeast culture(YC)supplements.The motivation for examining these alternatives comes from increasing consumer concern about the safety of chemical growth promoters in the animal feed industry,as well as the need for a safe food supply.Studies that have examined effects of YC have reported variable results.Some found that YC supplementation did not stimulate digestibility of DM,OM,CP,NDF,ADF,and/or N retention in lambs consuming total mixed rations(Adams et al.,1981;Angeles et al., 1998;Corona et al.,1999;Kawas et al.,2007a).In contrast,others have shown increased digestibility of CP,NDF,ADF and cellulose in dairy cattle(Wiedmeier et al.,1987;Erasmus et al.,1992;Wohlt et al.,1998)or steers(Plata et al.,1994;Cabrera et al.,2000).Yeast culture had has no effect on DM intake,live weight gain or feed conversion ratio of steers(Adams et al.,1981;Cole et al.,1992;Cabrera et al.,2000),midlactation dairy cows(Piva et al.,1993),orfinishing lambs(Kawas et al.,2007b).Others found that DM intake was higher in bulls fed YC,while live weight gain and feed conversion ratio did not differ between treated and control groups(Mutsvangwa et al.,1992).Erasmus et al. (1992)showed that YC increased DM intake of lactating dairy cows.Wehner et al.(1998) found that YC fed calves gained more weight than controls,but this did not reach statistical significance.Likewise,YC supplementation had no effect of on ADG of grazing growing steers(Cabrera et al.,2000)orfinishing lambs(Kawas et al.,2007b).Small ruminants constitute the majority of the ruminant population in developing coun-tries.Data available on feeding YC to small ruminants,such as kids,is scarce,and especially lacking with regard to carcass characteristics.Only one recent study was found in which carcass traits were evaluated,where Kawas et al.(2007b)showed that YC supplementation had no effect on slaughter or carcass traits offinishing lambs.Therefore,the objective of this study was to evaluate effects of a supplementary YC(Saccharomyces cerevisiae)culture to sheep and goat diets on nutrient digestibility,N balance,growth performance,and carcass composition and meat quality of fattened Awassi lambs and Shami goat kids.2.Materials and methodsTwo experiments were conducted,being a digestibility study and a fattening one. The same diet(Table1)was used in both experiments and it was offered as a totalH.H.Titi et al./Animal Feed Science and Technology142(2008)33–4335 Table1Ingredients and chemical composition of the diet used in experiments1and2g/kg S.E. Ingredients composition aBarley grain614.1Soybean meal133.5Wheat bran115.7Wheat straw117.0DiCalcium phosphate9.7Limestone 5.0Salt 4.0Vitamins/Mineral premix b 1.0Chemical composition(g/kg)DM926 1.3 OM947 1.5 CP168 5.6 aNDF282 3.7 ADF-ADF133 2.6a Dry matter basis.b Ruminant nutristar premix provides per kg:30,00,000IU vitamin A;10,00,000IU vitamin D3;10,000IU vitamin E;1600mg nicotinic acid;4000mg choline chloride;10,000mg DL-methionine;5000mg HCL-lysine; 90,000mg Fe;3000mg I;1000mg Cu;50,000mg Mn;50,000mg Zn;200mg Se;1,00,000mg Mg;30,000mg P; 10,3000mg Ca;11,200mg antioxidant(Endox),STAR INTERNATIONAL95520OSNY FRANCE.mixed ration(TMR).Two treatments were included in each experiment being the con-trol(C)that was not supplemented,and the treatment diet supplemented with YC. The YC was supplemented according to manufacturer recommendations at the level of12.6kg/tonne of DM(“XP”Yeast Culture,Diamond‘V’.Mills,Cedar Rapids, IA,USA).The guaranteed analysis provided by the manufacturer was not less than 120g/kg crude protein(CP),less than30g/kg crude fat and not more than65g/kg of crudefiber.The YC wasfirst hand mixed with the micro components mixture of the ration before being placed in the horizontal mixer for complete mixing with other TMR ingredients.Samples were collected after each mixing and kept frozen for later analysis.2.1.Experiment12.1.1.Animals and experimental procedureThe main objective of this study was to assess effects of adding YC on nutrient digestibil-ity coefficients and N retention of lambs.An in vivo digestibility experiment was used with 12intact male Awassi lambs of about150±10days of age and with an initial live weight (LW)of39.5±7.1kg at the beginning of the mbs were divided into two treatment groups of equal number according to LW and placed in individual metabolic cages equipped with a water container and meshedfloor.The study was completed for two consecutive experimental periods in a switch-over design.Each experimental period was15days in length,with9days for adaptation period and6days for sample collection. Lambs were fed ad libitum during the adaptation period and intake was restricted to0.9036H.H.Titi et al./Animal Feed Science and Technology142(2008)33–43of voluntary intake on individual basis during the collection mbs were fed once daily at09:00h and water was available at all time.Feces and urine were collected daily before feeding.Daily fecal output was composited for each lamb within the treatment for the collection period,then thoroughly mixed,and a 0.10representative sample preserved for later analysis.Urine excreted by each lamb over 24h was collected in300ml of HCl solution(3.0N)to avoid N loss.A0.10sample of collected urine was transferred to a5l container for each animal daily and kept at4◦C for later chemical analysis.2.2.Experiment22.2.1.Animals and experimental procedureThis experiment was conducted to determine effects of YC supplementation of the diet on growth performance of Awassi lambs and Shami kids in terms of DM intake,average daily gain(ADG),and feed conversion ratio(FCR),and to determine its effects on carcass composition and quality.A total of48Awassi male lambs and48Shami male kids were used.Animals of each species were divided into two groups of equal number based on LW. Each group was then randomly divided into3pens of8animals/mbs were around 120±7days old and weighed27.8±4.52kg,while kids were about105±7days old and weighed20.5±5.63kg.Animals were kept in an open shaded barn for the duration of the experiment.The LWs were measured at the beginning of the experiment and every14 days thereafter before feeding.The experimental period lasted12weeks.Feed was offered for14days for adaptation and then on an ad libitum basis.Animals were fed the same diets that were fed in experiment1.Feed consumption was measured as the difference between the amount offered and residues.The amount offered was adjusted daily based on the previous day’s consumption.Clean water was offered ad libitum for the whole period.By the end of the fattening period,12lambs and12kids(6/treatment,2/pen),were ran-domly selected,slaughtered and dressed at a commercial slaughterhouse following normal commercial procedures.Non-carcass components were weighed and recorded.Full weights of the foregut and intestines were weighed with all ingesta included,while empty weights were collected after being emptied and washed under running tap water and allowed to drip.Dressing proportions were calculated on a cold carcass weight basis and expressed as a proportion offinal fasting LW.Body length was measured on the whole carcass as the distance from the point where the gambrel is inserted to the base of the neck.Carcasses were halved along the vertebral column mid line.Each side was divided into five commercial cuts(i.e.,shoulder,rack,loin,leg,and tail),and cuts from both sides of every carcass were weighed.Linear measurements were made on the surfaces of the cuts,including back fat thickness,rib eye area,width and depth.Measurements were on the cut surface between rib12and13utilizing a metal ruler.After weighing,dissection was completed as quickly as possible to avoid moisture losses.Cuts were dissected into the components:Total muscles(M.semitendinosus,M.semimembranosus,and M.biceps femoris);total bone weight(bone plus cartilage);total fat(subcutaneous and intramuscular). The muscle(M.semitendinosus)of the right leg cut of each carcass was used for chemical analysis and subsequent determination of meat quality(Kawas et al.,2007b).H.H.Titi et al./Animal Feed Science and Technology142(2008)33–43372.3.Analysis procedureChemical analysis was according to AOAC(1990)procedures.Feed and fecal samples were ground by a Wiley mill(Arthur H.Thomas Co.,Philadelphia,PA,USA)through a 1mm screen and analyzed for DM in a forced air oven at100◦C for12h(method967.03). Urea and total N were determined using a Kjeldahl method of N determination using a Kjeltec1030Auto Analyzer following digestion(method976.06).Organic matter(OM) was also measured(method942.05).Concentrations of acid detergentfiber(ADF)and neutral detergentfiber(NDF)were determined according to Van Soest and Robertson(1980) using the ANKOM Fiber Analyzer(ANKOM Technology,Fairport,NY,USA).NDF was determined using sodium sulphite,heat stable alpha amylase and expressed inclusive of residual ash(aNDF).ADF was determined using cetyl trimethyl ammonium bromide and 1N H2SO4and expressed inclusive of residual ash(ADF).Chemical analysis of meat was according to the AOAC(1990)as specified above including analysis for ether extract(EE, method22.033).2.4.Statistical analysisData of both experiments were analyzed using the GLM option of SAS(2000).Means were analyzed using a least significant difference(LSD)method(Steel and Torrie,1986). The model of the fattening section included effects of treatment,species and treat-ment×species interaction in a2×2factorial design.Initial LWs were used as a covariate in the model utilized for LW.Pen was also in the model as the experimental unit for DM intake.The value for DM intake was the mean of three observations per treatment,while all other values were for individual animals.Carcass data was adjusted for fasting weight and cold carcass weight.Furthermore,week(period)was utilized in the model with a repeated measure design to study effects of YC supplementation on growth parameters throughout the experiment and initial BWs were used as a covariate for statistical analysis.3.Results3.1.Experiment1:Digestibility and N-retentionThere was no difference in DM intake(Table2),and only OM and ADF digestibilities for the treatment group were higher(P<0.05)than those for the controls.The N intake tended(P=0.08)to be higher for lambs fed YC,but there were no differences in total,fecal, or urinary N output between the control and YC supplemented groups.3.2.Experiment2:Fattening study3.2.1.Body weights,gain and feed intakeFinal BWs and average daily gain did not differ between control and YC supplemented groups(Table3).Average daily gain for lambs and kids as related to time of the feeding are in Fig.1.The DM intake also did not differ in lambs and kids fed the diet supplemented38H.H.Titi et al./Animal Feed Science and Technology142(2008)33–43Table2Effect of feeding yeast culture(YC)supplemented diet to Awassi lambs on digestibility coefficient of nutrients and N balanceC YC S.E.M.P1 Body weight(kg)39.238.5 4.200.60 DM intake(g/day)1071112371.90.20 Digestibility coefficient(g/kg)Dry matter7387567.80.30 Organic matter773b793a7.00.04 Crude protein7317448.30.50 Neutral detergentfiber46848027.50.70 Acid detergentfiber358b439a21.20.02 N BalanceN intake(g/day)28.730.3 1.500.08 Fecal N outputg/kg43840524.50.30 g/day7.87.60.500.50 Urinary N outputg/kg56259524.60.80 g/day10.111.6 1.100.20 Total N outputg/kg intake62663431.10.20 g/day17.919.2 1.400.60 Ng/kg intake37436630.90.40 g/day10.911.1 1.300.40 a,b Means with different superscripts within the same row are different(P<0.05).with YC and those of the control group(Table3).As a result,feed conversion ratio did not differ between yeast supplemented and control lambs or kids.3.2.2.Carcass measurements and cutsYeast culture supplementation decreased cold dressing proportion and increased (P<0.05)empty digestive tract weight(Table4),but only in lambs.These changes were not associated with differences in weight of external and/or internal organs,or internal fat. Table3Growth,feed intake and feed conversion ratio of Awassi lambs and Shami goat kids after yeast culture(YC) supplementationLambs Kids P aC YC C YC S.E.M.T S T×S No.of animals24242424Initial BW(kg)27.827.620.020.20.600.500.100.20 Final BW(kg)49.749.932.532.10.800.020.040.60 Average daily gain(g/day)26126614914212.00.010.010.40 DM intake(g/day)313132885387431.00.700.010.80 Feed conversion ratio 5.4 5.3 6.1 6.50.400.100.400.10 a T:treatment effect,S:species effect.H.H.Titi et al./Animal Feed Science and Technology142(2008)33–4339Fig.1.Average daily gain of lambs and kids during fattening on the control and yeast supplemented diets. Lower dressing proportion of treated lambs would mostly be a result of increased weight of non-carcass,especially the digestive tract.Increased empty digestive tract weight could indicate increased DM intake and/or higher body fat.Prime carcass cuts(i.e.,leg,loin, rack,shoulder,and tail)did not differ for lambs or kids fed control or YC supplemented diets(Table5).However,only leg and shoulder cuts in kids were different(P<0.05)when expressed as a proportion of total carcass weight.Leg of the control kids was higher com-pared to that for YC supplemented ones,while the shoulder proportion was higher in YC supplemented kids.Table4Carcass characteristics and linear measurements of Awassi lambs and Shami kids as influenced by the yeast culture (YC)supplementationLambs Kids S.E.M.P fC YC C YC T S T×S No.of animals6666CharacteristicsFasting weight a(kg)42.342.137.738.00.500.800.010.30 Hot carcass weight(kg)23.0a20.8b21.121.80.700.200.600.01 Dressing proportion0.526a0.478b0.5460.562 1.200.300.040.03 HSF b weight(kg)8.18.7 5.6 5.90.300.100.050.50 LHKSLS c weight(kg) 1.5 1.7 2.1 2.10.100.300.020.10 Total fat d weight(kg)0.050.100.400.500.100.500.02 1.00 Empty digestive tract(kg) 2.1a 2.5b 3.6 3.20.200.600.030.03 Linear measurementsBody length(cm)96.198.917.9115.0 2.100.400.100.40 Fat thickness e(mm) 6.68.2 4.1 4.00.700.500.100.30 Rib eye width(mm)61.359.956.756.3 2.000.400.100.30 Rib eye depth(mm)29.129.226.725.60.900.700.200.90 a,b Means with different superscripts within the same row are different(P<0.05).a Average weight of6animals/treatment,adjusted to constant fasting weight.b HSF:weight of head+skin+feet.c LHKSLS:weight of liver+heart+kidneys+spleen+lung+sweetbread.d Fat weight:fat of heart+kidney+pelvic.e Over M.longissimus dorsi(eye muscle).f T:treatment effect,S:species effect.40H.H.Titi et al./Animal Feed Science and Technology142(2008)33–43Table5Wholesale cuts of Awassi lambs and Shami kids as influenced by the yeast culture(YC)supplementation Lambs Kids P aC YC C YC S.E.M.T S T×S Legkg 6.1 5.9 6.3 6.10.200.300.100.50 Proportion0.2870.2830.321a0.302b0.700.050.100.03 Lionkg 2.2 2.3 2.3 2.30.10 1.000.800.50 Proportion0.1080.1070.1180.1130.500.800.500.50 Rackkg 2.0 1.9 2.1 2.20.100.500.400.30 Proportion0.990.930.1070.1090.500.500.300.30 Shoulderkg7.27.39.19.40.200.030.010.80 Proportion0.3580.3580.449b0.470a0.600.040.010.02 Tailkg 3.3 3.40.70.60.200.900.010.90 Proportion0.1490.1590.600.600.900.500.010.50 a,b Means with different superscripts within the same row are different(P<0.05).a T:treatment effect,S:species effect.3.2.3.Dissection and chemical compositionTotal muscle/bone(M/B)ratio(Table6)was lower(P<0.05)for YC treated lambs versus control,but there were no differences in kids.Proportions of protein content in lambs was Table6Physical dissection of leg cut and chemical composition of muscle of Awassi lambs and Shami kids as influenced by the yeast culture(YC)supplementationLambs Kids P aC YC C YC S.E.M.T S T×S Physical dissection of leg cutTotal muscle proportion0.6080.5890.6300.627 1.300.400.010.30 Total fat proportion0.2320.2260.1460.1560.900.600.010.80 Total bone proportion0.1580.1720.2150.2070.800.500.05 1.00 TM/B ratio b 4.0a 3.5b 2.9 3.00.200.100.010.04 S.coetaneous fat/total fat73.173.856.655.1 3.800.400.010.70 Intramuscular fat/total fat27.026.243.444.9 4.000.600.010.80 Chemical composition c,proportionMoisture0.2250.23.20.2260.2230.400.300.100.50 Crude protein0.823a0.79.4b0.8040.811 2.500.400.010.03 Ether extract0.137b0.171a0.1720.156 1.200.700.010.04 Ash0.0510.0470.0460.0490.300.300.100.30 a,b Means with different superscripts within the same row are different(P<0.05).a T:treatment effect,S:species effect.b Total muscle/bon ratio.c Leg muscle sample.H.H.Titi et al./Animal Feed Science and Technology142(2008)33–4341 lower(P<0.05),and ether extract was higher(P<0.05),when YC was supplemented to the diets.4.Discussion4.1.Experiment1:Digestibility and N-retentionAlack of digestibility differences with YC supplementation are consistent with others who reported that supplemental YC failed to improve digestion coefficients of different diet components in sheep or lambs(Adams et al.,1981;Andrighetto et al.,1993;Angeles et al., 1998;Kawas et al.,2007a),bulls and steers(Mutsvangwa et al.,1992;Cabrera et al.,2000) or lactating dairy cows(Arambel and Kent,1990).Cole et al.(1992)reported that lambs fed YC in their diets had numerically higher apparent DM and N digestibility.In our case,lambs were fed a highly digestible concentrate diet,which could have masked positive effects of YC supplementation on digestibility.Another possibility could be that the low forage quality prevented benefits.Roa et al.(1997)showed that high benefits can be obtained with good quality ck of response to YC with low quality diets has also been reported by Cabrera et al.(2000).The improved ADF digestibility is consistent with others who reported that using YC improved ADF digestibility in dairy cattle(Erasmus et al.,1992;Wohlt et al.,1998)or steers (Plata et al.,1994).This might be related to increased concentrations of cellulolytic bacteria in the rumen(Wiedmeier et al.,1987;Harrison et al.,1988).Wiedmeier et al.(1987)and Plata et al.(1994)suggested that adding a YC supplement can stimulate rumen fermentation by increasing the number and proportion of cellulolytic bacteria in the rumen.However, Harrison et al.(1988)reported that,although YC stimulated an increase in the number of cellulytic bacteria,the activity of these organisms was decreased.Results of N balance are consistent with those of Mutsvangwa et al.(1992)and Kawas et al.(2007a)who reported no effect of supplementing YC on N parameters in bulls and lambs.In contrast,lambs fed YC had higher N retention than control lambs(Cole et al., 1992).In our case,lambs were fed on a diet with adequate CP(168g/kg)which could be a reason for no effect of YC supplementation on digestibility or N balance.4.2.Experiment2:Fattening study4.2.1.Body weights,gain and feed intakeImproved growth with YC supplementation has been reported with steers(Adams et al.,1981;Cabrera et al.,2000),calves(Cole et al.,1992),bulls(El Hassan et al.,1996; Mutsvangwa et al.,1992),andfinishing lambs(Kawas et al.,2007b).Kawas et al.(2007b) reported that addition of YC improved weight gain in lambs fed low protein diets with no benefit with those fed high protein diets.In our case,the relative high diet CP content could have prevented effects of YC supplementation on growth rate.The relationship between YC supplementation and CP level in the diet suggested no beneficial effect of YC on DM intake at high CP levels,but that could improve DM intake of diets with low CP levels(Kawas et al.,2007b).42H.H.Titi et al./Animal Feed Science and Technology142(2008)33–43Reasons behind the different responses to YC supplementation between our study and those of others are not clear.Cole et al.(1992)reported that the YC can have beneficial effects on performance under some circumstances,but there seems to be considerable unexplained variability in response.This could be due to factors such as basal diet,viable cell numbers in the YC,amount of YC supplemented,type of forage fed,and feeding strategy(Piva et al., 1993;Cabrera et al.,2000;Kawas et al.,2007b).For example,there was a greater beneficial effect of YC with forage based diets versus high concentrate diets(Kawas et al.,2007b).4.2.2.Carcass measurements and carcass cutsCarcass measurements were adjusted to a constant fasting weight and to a constant carcass weight for non-carcass components.Very little published literature is available concerning effects of YC supplementation on carcass characteristics,especially with kids. However,similar results were reported with Mir and Mir(1994)who reported no effects of YC supplementation on dressing proportions of growing steers.Basiony et al.(1998) indicated that YC supplementation did not influence carcass characteristics of buffalo calves. Recently,Kawas et al.(2007b)showed that YC had no effect on hot and chilled carcass weights,or dressing proportions of lambs fed a high grainfinishing diet due to no differences in DM intake.Reason for similarity in carcass cuts could be due to similar growth and LW gain during our fattening period.4.2.3.Dissection and chemical compositionLower protein content of the leg in YC treated lambs could indicate increased fat content of leg muscle.Indeed fat content was higher in treated lambs.Higher fat content could be related to changes in ruminal fermentation and metabolic end products.Several stud-ies reported that adding YC to ruminant diets resulted in low acetate:propionate ratio in the rumen(Harrison et al.,1988;Erasmus et al.,1992).Moreover,Erasmus et al.(1992) suggested that this lower ratio results from increased propionate production.5.ConclusionsResults show species variability in response to YC supplementation.It also indicated that YC supplementation improved digestibility of 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