Effects of gender, time of castration, genotype and feeding regimen on lamb growth and carcass fatness

Two concurrent trials were conducted to examine the effects of gender, time of castration, genotype and feeding regimen on lamb growth rate and carcass fatness. Trial 1 compared Polypay and Coopworth x Polypay male lambs either left intact or castrated early, mid or late in growth. Trial 2 compared Hampshire-sired lambs (females, early castrate wethers and late castrate wethers) from Suffolk x Coopworth dams and whiteface x Coopworth dams. Gender and time of castration significantly affected growth rate in Trial 1 but not in Trial 2. Rams were more efficient than wethers, but no other gender or time of castration effects on feed efficiency were observed. Delaying castration and pasture grazing both reduced fatness. Lambs grazed on irrigated pastures until they weighed 41 kg then finished in drylot had a lower dressing percentage than lambs fed in the drylot throughout, but USDA quality grades were similar. Substitution of Polypay genes by Coopworth genes in crossbred lambs did not significantly alter any of the fatness traits measured but increased ribeye area. Hampshire-sired lambs grew faster than whiteface lambs, particularly in drylot. They had a higher dressing percentage without increased fatness, apparently because of greater muscling in ribeye and leg.     

Postmortem proteolysis in longissimus muscle from beef, lamb and pork carcasses

Postmortem proteolysis in skeletal muscle and factors affecting this process were examined in pork, lamb and beef longissimus muscles (LM) to determine the cause of differences in meat tenderness among these species. Fat thickness differed among species in the following order: pork greater than beef greater than lamb. The following patterns were observed for rate of temperature and pH decline: lamb greater than pork greater than beef and pork greater than beef greater than lamb, respectively. At 1 d postmortem, pork was the most tender, followed by beef and lamb, respectively. Between 1 and 14 d of postmortem storage, lamb LM was the most improved in tenderness, followed by beef and pork, respectively. Species did not differ (P greater than .05) in LM collagen solubility. Pork LM from fed pigs had the highest (P less than .05) level of cathepsins B + L and cystatin(s) activities, whereas no differences (P greater than .05) were observed among the species for cathepsin B activity. The lowest (P less than .01) Ca2(+)-dependent protease (CDP)-II and CDP inhibitor activities were observed in pork LM. Beef LM had the highest CDP inhibitor activity (P less than .05) but was intermediate in CDP-II activity. No differences were observed among species for CDP-I activity. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of myofibrils isolated at 0, 1 and 14 d postmortem indicated that by d 1, desmin hydrolysis was most extensive in pork muscle, followed by lamb and beef.(ABSTRACT TRUNCATED AT 250 WORDS)     

Rigor temperature and meat quality characteristics of lamb longissimus muscle

The present experiment was conducted to determine the effect of muscle temperature during the prerigor and early postrigor period on meat tenderness, postmortem proteolysis, calpain system activity, water-holding capacity, and color. Lamb longissimus muscle (n = 14) from the right and left carcass sides was excised immediately after dressing, divided into an anterior and posterior sample, vacuum-packaged, and stored overnight at 5 to 35 degrees C. Further storage, up to 14 d postmortem, was at 2 degrees C. Tenderness at 1 d postmortem, tenderization during further storage, and postmortem proteolysis were negatively affected by overnight incubation above 25 degrees C. This effect could be explained by an effect of temperature on muscle contraction and activity of the calpain system. Muscle contraction was at a minimum after incubation at 15 degrees C. Water-holding capacity was negatively affected by incubation above 25 degrees C. Color scores improved with increasing incubation temperature at 1 d postmortem. However, after 14 d of postmortem storage, no differences in color scores were observed. Based on the present results and results of other groups, a temperature around 15 degrees C at the onset of rigor seems optimal to maximize tenderness without having detrimental effects on water-holding capacity or color.     

Evaluation of sampling, cookery, and shear force protocols for objective evaluation of lamb longissimus tenderness

Experiments were conducted to compare the effects of two cookery methods, two shear force procedures, and sampling location within non-callipyge and callipyge lamb LM on the magnitude, variance, and repeatability of LM shear force data. In Exp. 1, 15 non-callipyge and 15 callipyge carcasses were sampled, and Warner-Bratzler shear force (WBSF) was determined for both sides of each carcass at three locations along the length (anterior to posterior) of the LM, whereas slice shear force (SSF) was determined for both sides of each carcass at only one location. For approximately half the carcasses within each genotype, LM chops were cooked for a constant amount of time using a belt grill, and chops of the remaining carcasses were cooked to a constant endpoint temperature using open-hearth electric broilers. Regardless of cooking method and sampling location, repeatability estimates were at least 0.8 for LM WBSF and SSF. For WBSF, repeatability estimates were slightly higher at the anterior location (0.93 to 0.98) than the posterior location (0.88 to 0.90). The difference in repeatability between locations was probably a function of a greater level of variation in shear force at the anterior location. For callipyge LM, WBSF was higher (P < 0.001) at the anterior location than at the middle or posterior locations. For non-callipyge LM, WBSF was lower (P < 0.001) at the anterior location than at the middle or posterior locations. Consequently, the difference in WBSF between callipyge and non-callipyge LM was largest at the anterior location. Experiment 2 was conducted to obtain an estimate of the repeatability of SSF for lamb LM chops cooked with the belt grill using a larger number of animals (n = 87). In Exp. 2, LM chops were obtained from matching locations of both sides of 44 non-callipyge and 43 callipyge carcasses. Chops were cooked with a belt grill and SSF was measured, and repeatability was estimated to be 0.95. Repeatable estimates of lamb LM tenderness can be achieved either by cooking to a constant endpoint temperature with electric broilers or cooking for a constant amount of time with a belt grill. Likewise, repeatable estimates of lamb LM tenderness can be achieved with WBSF or SSF. However, use of belt grill cookery and the SSF technique could decrease time requirements which would decrease research costs.     

Effects of breed, sex, and halothane genotype on fatty acid composition of pork longissimus muscle

The objective of this study was to estimate the effects of breed, sex, and halothane genotype on fatty acid composition and several fatty acid indices of lipid extracted from porcine LM. Purebred Yorkshire (n = 436), Duroc (n = 353), Hampshire (n = 218), Spotted (n = 187), Chester White (n = 173), Poland China (n = 124), Berkshire (n = 256), and Landrace (n = 187) pigs (n = 1,934; 1,128 barrows and 806 gilts) from 1991, 1992, 1994, and 2001 National Barrow Show Sire Progeny Tests were used. Pigs were classified as the HAL-1843 normal (NN) genotype (n = 1,718) or the HAL-1843 carrier (Nn) genotype (n = 216). For statistical analysis, a mixed model was used that included fixed effects of breed, sex, halothane genotype, test, slaughter date, interaction of breed x sex, and random effects of sire and dam within breed. Breed significantly affected the concentration of individual fatty acids, total lipid content, and the values of several fatty acid indices of LM. Duroc pigs had the greatest (P < 0.01) content of total SFA. Total MUFA concentration in Poland China pigs was greater (P < 0.05) than in all other breeds except the Spotted (P > 0.05). The concentrations of total PUFA were greater (P < 0.01) in Hampshire, Landrace, and Yorkshire pigs compared with those of other breeds. Significant sex differences for individual fatty acids were detected. Compared with gilts, barrows had greater (P < 0.01) concentrations of SFA and MUFA but lower (P < 0.01) total PUFA. Halothane genotype was a significant source of variation for the percentages of some fatty acids. Pigs with the carrier (Nn) genotype had lower concentrations of SFA (P < 0.05) and MUFA (P < 0.01) but a greater concentration of PUFA (P < 0.01) compared with NN pigs. There were significant negative correlations between total lipid content and individual PUFA and significant positive correlations between lipid concentration and most individual SFA and MUFA. In conclusion, the results suggest that breed and sex are important sources of variation for fatty acid composition of LM.     

Effect of early gestation feeding, birth weight, and gender of progeny on muscle fiber characteristics of pigs at slaughter

Maternal nutrition and progeny birth weight affect muscle fiber development in the pig, thereby influencing early postnatal growth rate. The objective of the study was to determine the extent to which growth, morphometric characteristics, and area and distribution of slow-oxidative (SO), fast oxidative-glycolytic (FOG), and fast glycolytic (FG) fibers of three muscles (LM = longissimus muscle; RF = rectus femoris; ST = semitendinosus) of slaughter pigs were affected by DE intake level during the first 50 d of gestation. Multiparous Swiss Large White sows were assigned randomly to one of three energy intake treatments: 1) fed 2.8 kg/d of a standard diet (STD; n = 6) containing 10.7 MJ DE/kg; 2) fed 2.8 kg/d of a low-energy diet (LE; n = 5) containing 6.6 MJ DE/kg; or 3) fed 4.0 kg/d of a standard diet (HE; n = 5) containing 10.7 MJ DE/kg (as-fed basis). Sows were subjected to energy intake treatments for the first 50 d of gestation; however, from d 51 to parturition, sows received 2.8 kg/d of the standard diet, and the amount of feed offered each sow during lactation was adjusted according to the litter size. Sows farrowed normally and pig birth weights were recorded. Based on birth weight, the two lightest (1.27 kg; Lt) and two heaviest (1.76 kg; Hvy) barrows and gilts from the 16 litters (n = 64) were selected at weaning and were offered a fixed amount of feed (170 g x BW(0.569)/d) from 25 to 105 kg BW. Regardless of the birth weight, progeny from HE sows grew slower (P < 0.05) during lactation and the growing-finishing period, had a lower (P < 0.05) gain-to-feed ratios, and had higher (P < 0.05) percentages of adipose tissue than pigs born from LE sows. The ST was shorter (P = 0.03) in Lt than in Hvy pigs, and the ST of gilts was heavier (P = 0.01) and had a larger (P = 0.01) girth than the ST of barrows. Overall mean fiber area tended to be larger (P < or = 0.11) in the LM and light portion of the ST of Lt than in Hvy pigs, and was larger (P = 0.03) in the ST of gilts than barrows. The ST of progeny from LE sows had fewer (P < 0.10) FG fibers, which was compensated by either more (P < 0.05) FOG in the light portion of the ST, or more (P < 0.10) SO fibers in the dark portion, and these differences were more pronounced in Lt pigs than in Hvy pigs. Overall, maternal feeding regimen affected muscle fiber type distribution, whereas birth weight and gender affected muscle fiber area.     

小黑麦干草对羔羊生产性能及采食行为的影响

为探究小黑麦(×Triticale Wittmack)干草对舍饲羔羊生产性能和采食行为的影响,本研究选用18只舍饲湖羊公羔,随机分为对照组、试验Ⅰ组和Ⅱ组,每组6只;对照组饲喂基础日粮,试验Ⅰ组和Ⅱ组在基础日粮中分别用10%、20%的小黑麦干草等量替代粗料。结果表明:Ⅰ组试验羊的平均日增重为189.72 g,显著高于对照组和Ⅱ组(P <0.05);试验羊采食量随小黑麦干草添加比例的增加而降低,Ⅱ组采食量显著低于Ⅰ组和对照组(P <0.05),采食时长极显著高于Ⅰ组和对照组(P <0.01);Ⅰ组试验羊排泄次数显著高于对照组(P <0.05),与Ⅱ组无显著差异(P> 0.05);Ⅰ组试验羊反刍周期、反刍时间、反刍食团数和食团咀嚼总次数都极显著高于Ⅱ组(P <0.01)。综上可知,小黑麦干草作为粗饲料在羔羊日粮中适宜添加比例为10%,这为小黑麦干草饲料化开发利用提供了理论基础。     

初乳特点及喂养羔羊方法简述

初乳是指动物产仔或产犊后最初几天所分泌的乳汁,山羊一般指产羔后2 d内所分泌的乳汁,母牛是指产后5 d内或7 d内所分泌的乳汁,几乎所有哺乳动物的初乳均指产后不超过1周内分泌的乳汁.此时的乳汁营养价值高、抗病力强、易消化吸收,充分利用会促进培育羔羊的经济效益.     

Immunohistochemical characterization of canine prostatic carcinoma and correlation with castration status and castration time

The purpose of this study was to characterize canine prostate cancer using immunohistochemical staining specific for acinar and urothelial/ductal tissue and correlate these results with the dogs' castration status/castration time. Seventy dogs with prostate cancer were included, 71% were castrated and 29% were intact. Compared with an age‐matched control population, castrated dogs were at increased risk of prostate cancer, odds ratio 3.9. Immunohistochemical staining was performed on 58 cases. Forty‐six of the 58 stained positive for cytokeratin 7 (CK 7) (ductal/urothelial origin) and one of the 58 stained positive for prostate‐specific antigen. Dogs with CK 7‐positive tumours were younger when castrated than dogs with CK 7‐negative tumours, 2 versus 7 years (P = 0.03); dogs castrated at ≤2 years of age were more likely to be CK 7‐positive (P = 0.009). These results show that most canine prostatic carcinomas are of ductal/urothelial, androgen‐independent origin. This is consistent with the epidemiological findings, showing increased risk in castrated dogs. Canine prostate cancer may, therefore, not be a realistic model for the human disease.     

Influence of swine genotype on fatty acid composition of phospholipids in longissimus muscle.

Our objective for this study was to determine whether there is a difference in the fatty acid composition of phospholipids in longissimus muscle from pigs of different genotypes. In Exp. 1, 15 Hampshire x Yorkshire-Landrace (YL), 15 Duroc x YL, and 15 Danbred x YL were used. Animals were of similar age and were fed identical diets. In Exp. 2, longissimus muscle samples from pigs of seven genetically different lines were analyzed. In both experiments, saturated fatty acids (SFA, 16:0 and 18:0) constituted approximately 31.5% of the total fatty acids. Monounsaturated fatty acid (MUFA, 18:1 and 20:1) levels ranged from 12.3 to 16.9%, and PUFA (mainly 18:2 and 20:4) accounted for 50.8 to 57.0% of the total fatty acids. Fatty acid composition of muscle phospholipids from Duroc and Hampshire x YL pigs was identical. Muscle phospholipids from Danbred x YL pigs contained more PUFA (approximately 3%, P < .05) and less SFA (approximately 2%, P < .05) than phospholipids from the two other genotypes. Differences in SFA and PUFA of muscle from the seven lines were of the same order of magnitude. Differences in MUFA content were not significant.     

Effects of breed, sex and halothane genotype on fatty acid composition of triacylglycerols and phospholipids in pork longissimus muscle

The objective of this study was to estimate the effects of breed, sex, and halothane (HAL‐1843^TM) genotype on fatty acid composition of triacylglycerols (TAG) and phospholipids (PL) extracted from porcine longissimus muscle (LM). Purebred Yorkshire (n = 131), Duroc (n = 136), Hampshire (n = 49), Spotted (n = 35), Chester White (n = 74), Poland China (n = 51), Berkshire (n = 169) and Landrace (n = 82) pigs (n = 727; 427 barrows and 300 gilts) from the 1994 and 2001 National Barrow Show Sire Progeny Tests were used. For statistical analyses, a mixed model was used that included fixed effects of breed, sex, HAL‐1843^TM genotype, year, slaughter date within each year, interaction of breed × sex and random effects of sire and dam within breed. Breeds and sex were significantly associated with the percentages of the majority fatty acids in TAG. Duroc pigs had greater total saturated fatty acids (SFA) and lower total monounsaturated fatty acids (MUFA) (p < 0.05) contents than did pigs of all other breeds except Berkshire (p > 0.05). The concentration of total polyunsaturated fatty acids (PUFA) was the greatest in Hampshire pigs (p < 0.05). The content of total SFA was greater (p < 0.01), whereas the concentrations of total MUFA and PUFA were lower (p < 0.01) in barrows than those in gilts. The contents of major SFA in PL did not differ significantly among pigs from different breeds and sex groups. However, breed and sex significantly affected the concentrations of major MUFA and PUFA in PL and strong negative correlation between the total contents of MUFA and PUFA in PL was observed in the current study. Chester White pigs had greater total MUFA and lower total PUFA contents (p < 0.05) in PL than did pigs of all other breeds except Spotted (p > 0.05). In contrast to breed and sex effects, the concentrations of fatty acids in PL were more affected by HAL‐1843^TM genotype than those in TAG. The content of C16:0, a major SFA in PL, differed significantly in pigs with different HAL‐1843^TM genotypes. In conclusion, these results suggest that breed and sex are important sources of the variations for fatty acid composition of TAG and PL in LM.     

Effect of breed-type and feeding regimen on goat carcass traits

Meat-type (Boer x Spanish and Spanish) goats from two feeding regimens (feedlot and range) were slaughtered and live and carcass weights were obtained. At 24 h after death, various yield and quality measurements were collected. One side from each carcass was fabricated into major wholesale cuts for dissection into major carcass components. Feedlot goats had heavier (P<.05) live and carcass weights and carcasses that yielded more (P<.05) dissectible fat and lean and less (P<.05) bone, as a percentage of carcass weight, than did the carcasses of range goats. In the feedlot environment, Boer x Spanish goats had greater (P<.05) live weights, carcass weights, actual and adjusted fat thicknesses, carcass conformation scores, and leg circumference scores than did Spanish goats of similar age. The only breed-type differences that were significant after adjusting for live weight using analysis of covariance were that Boer x Spanish goats in the feedlot treatment had greater (P<.05) actual and adjusted fat thickness and carcass conformation than Spanish goats on the feedlot treatment. The Boer x Spanish goat carcass trait advantage could mainly be attributed to their larger size and enhanced capacity for growth.     

The extent of proteolysis is independent of sarcomere length in lamb longissimus and psoas major.

The objective of this experiment was to determine the effect of sarcomere length on postmortem proteolysis and meat tenderness. Eighteen Dorset market-weight sheep were slaughtered conventionally. The longissimus thoracis et lumborum and psoas major from each carcass were either left intact on the carcass (control), which was chilled at 0 degrees C, or excised from the carcass and chilled in an ice slurry (0 degrees C). At 24 h, control muscles were excised, and all muscles were cut into sections and assigned to 1 or 10 d of postmortem storage at 2 degrees C. Sarcomere length was shorter (P < .01), as intended, in the shortened relative to the control treatment and in longissimus relative to psoas major (1.36 vs 1.69 microm, raw longissimus; 1.45 vs 3.03 microm, raw psoas major). Sarcomere length was not affected (P > .05) by aging time. Western blot analysis of troponin-T and desmin indicated no effect (P > .05) of the shortened treatment compared to the control on the extent of proteolysis. Regardless of aging time or treatment, troponin-T was more degraded (P < .01) in longissimus than in psoas major (38.1 vs 23.5%) and desmin tended to be more degraded (P = .08) in longissimus than in psoas major (50.4 vs 35.1%). Regardless of muscle or treatment, aging 10 d compared to 1 d increased degradation of troponin-T (46.3 vs 15.3%) and desmin (69.3 vs 16.1%). Warner-Bratzler shear force was greater (P < .01) in the shortened treatment than in control (6.9 vs 3.8 kg), greater (P < .01) in longissimus than in the psoas major (6.5 vs 4.2 kg), and greater (P < .01) with 1 d than with 10 d of aging time (6.1 vs 4.6 kg). A muscle x aging time interaction (P < .05) indicated shear force declined more in longissimus than in psoas major during aging. We conclude that sarcomere length did not affect the extent of proteolysis. However, sarcomere length may have an indirect effect on tenderization during aging due to its effect on initial tenderness.     

不同饲喂方式对生长猪背最长肌中钙蛋白酶抑制蛋白表达量以及肉嫩度的影响

为研究不同饲喂方式对猪背最长肌钙蛋白酶抑制蛋白(calpastatin)表达量以及肉嫩度的影响,选用54头约60kg的三元杂交生长肥育猪,随机分为3个处理,每个处理3个重复,每个重复6头猪,分别按照自由采食组(对照)、限饲组(30%)、补偿生长组(前20d限饲30%后20d自由采食)进行不同的饲养。试验结果表明:自由组、补偿生长组、限饲组的肌纤维剪切力和钙蛋白酶抑制蛋白表达量依次显著升高,且随着钙蛋白酶抑制蛋白表达量的增多,剪切力值有上升的趋势。     

Effect of sex and exogenous porcine somatotropin on longissimus muscle fiber characteristics of growing pigs

Thirty-seven pigs with an initial live weight of 60 kg were used to investigate the effects of daily exogenous porcine somatotropin (pST) administration at two dose levels (0 and 100 micrograms.kg-1.d-1) for a 31-d period on muscle fiber characteristics and meat tenderness of boars, gilts and barrows. Excipient boars and gilts had more alpha W and fewer alpha R fibers than did those receiving pST. The percentage of muscle fiber type for barrows was not affected by pST treatment. The administration of pST resulted in an increase in muscle fiber size for all three fiber types in all three sexes, but these changes were of greater magnitude in barrows (31.8%) and gilts (27.8%) than in boars (9.3%). Somatotropin negated the intrinsic sex effect differences in fiber area of the pigs. There was no difference in tenderness among excipient boars, barrows and gilts; however, with the inclusion of pST, shear force decreased in boars and gilts and increased in barrows. A high proportion of the pST-treated pigs contained giant fibers in the longissimus muscle. Furthermore, a small proportion of the pST-treated pigs exhibited pale, soft, exudative muscle. Whether the giant fiber anomalies occurred through increased muscle activity or from fibers undergoing degenerative changes was not determined.     

Effects of feeding ergovaline on lamb performance in a heat stress environment

Lambs exposed to a heat-stressed environment (33 degrees C, 50% relative humidity) were used in three experiments to determine whether ergovaline (EV) is the primary toxin involved in fescue toxicosis. The first study evaluated the effects of feeding diets containing increasing levels of endophyte-infected tall fescue seed (E+) and decreasing levels of endophyte-free tall fescue seed (E-). The second and third study evaluated the response to a diet that contained synthetic EV added to an E- diet and the response to a diet containing endophyte-infected ryegrass seed (R+) with an elevated concentration of EV. In Exp. 1, lambs were fed diets of: 1) 10% E- and 0% E+, 2) 5% E- and 5% E+, or 3) 0% E- and 10% E+. Increasing the percentage of E+ in the diet resulted in a linear decrease (P < 0.01) in feed intake (as-fed basis), skin temperature, thermocirculation index (TCI), and serum prolactin. Body weight gain also decreased (P < 0.06). Respiratory rate and core body temperature were not affected by the 5 or 10% E+ diets. In Exp. 2, lambs were fed diets that contained: 1) 10% E-, 2) 10% E- with synthetic EV added at a level equivalent to the 10% E+ diet, or 3) 10% E+. Feed intake (as-fed basis), body weight gain, and skin temperature did not differ for lambs fed the E- and EV diets. The EV diet elicited a decrease (P < 0.05) in TCI and prolactin compared with the E- diet. The TCI for lambs fed EV did not differ (P > 0.10) from the E+ lambs; however, serum prolactin was lower (P < 0.05) for lambs on the E+ diet than for those fed EV. Core body temperature was not affected (P > 0.10) by feeding EV or E+ fescue seed in Exp. 2. In Exp. 3, lambs were fed diets that contained: 1) 10% E-, 2) 3.24% R+ and 6.76% E-, which added an equivalent amount of EV to E+ diets but reduced concentrations of other ergot alkaloids, or 3) 10% E+. Lambs fed the E+ diet and maintained at 33 degrees C had lowered feed intake (as-fed basis), skin temperature, and TCI compared with lambs fed the E- or R+ diets (P < 0.05). Lambs fed the E+ diet had increased rectal temperatures and lowered serum prolactin compared with lambs on the R+ diet (P < 0.05). Lambs on the R+ diet had a greater rectal temperature and lower serum prolactin than lambs on the E- diet (P < 0.05). These results suggest that EV is a fescue toxin; however, other alkaloids might work synergistically with EV, causing the full expression of fescue toxicosis.     

荒漠草原区饲草组合对苏尼特羔羊的饲喂效果

为合理利用荒漠草原区饲草资源,本研究分别以华北驼绒藜（Ceratoides arborescens）和紫花苜蓿(Medicago sativa)为主要饲草,配合谷草（Setavia italica）、冰草(Agropyron cristatum)饲喂苏尼特羔羊,根据组合效应原理科学组合为6组：100%驼绒藜、50%驼绒藜+50%谷草、50%驼绒藜+50%冰草、100%苜蓿、50%苜蓿+50%谷草和50%苜蓿+50%冰草。结果表明,100%苜蓿饲喂的羔羊增重、屠宰率和净肉率都明显高于其它处理,饲喂效果最好。不同组合饲喂效果为：50%驼绒藜+50%谷草＞100%驼绒藜、50%驼绒藜+50%冰草;100%苜蓿＞50%苜蓿+50%谷草、50%苜蓿+50%冰草。