性别对关中黑猪生长性能及血液生化指标的影响

为探讨不同性别对关中黑猪生长性能、血液指标及宰前应激的影响,选取10头体重(6.34±0.14)kg的关中黑猪,公母各半,进行分栏饲养,公猪在7日龄去势。分阶段对关中黑猪的体尺进行测量,并在屠宰时采集其血液,对其血液常规指标和应激指标进行检测。结果显示,关中黑猪去势公猪体重自5月龄起显著高于母猪(P0.05),体长在2月龄和8月龄显著高于母猪(P0.05),体高和腿臀围在2月龄和6月龄显著高于母猪(P0.05),胸围自6月龄起显著高于母猪(P0.05)。关中黑猪的血液生化指标在性别间无显著影响(P0.05)。关中黑猪去势公猪血液中肌酸激酶含量显著低于母猪(P0.05),并且检测到血液中乳酸含量也有同样趋势。综合考虑得出,关中黑猪去势公猪的生长性能及抗应激性能优于母猪。     

姜曲海瘦肉型品系母猪早期生殖激素变化的研究

用放射免疫测定法(RIA),以姜曲海瘦肉型品系零世代母猪及亲本为试验材料,用前腔静脉连续采血方法,在初生,15,30,45,60,75日龄时,对其体内5种生殖激素浓度的变化进行了对比研究。结果表明,初生时,各生殖激素浓度均处于高浓度水平;0～75日龄阶段血清LH(75日龄除外)、FSH(30日龄除外)和E2(初生时除外)平均水平零世代极显著低于亲本(P<0.01),而P(初生时除外)和T(30,45日龄除外)平均水平二者无显著差异(P>0.05);在60～75日龄囊状卵泡出现前的阶段,LH、FSH和E2浓度均出现明显上升趋势。     

不同日龄北京黑猪卵巢发育的研究

对30～180日龄北京黑猪母猪卵巢形态学和组织学的研究结果表明,在60日龄以前卵巢体积缓慢增长,60日龄以后直到120日龄迅速增长,150～180日龄之间增长速度减慢。90日龄卵巢切片上,首先观察到有腔卵泡。卵泡总数随日龄增加而减少,闭锁率增高。一半180日龄母猪卵巢上有成熟黄体。根据实验结果,提出北京黑猪母猪初情期在170日龄左右。     

性别对关中黑猪胴体性状、肉品质以及脂代谢相关基因表达的影响

为探究性别对关中黑猪胴体性状、肉品质以及脂代谢相关基因表达的影响,本实验选用10头体重为(6.34±0.14)kg的关中黑猪,公、母各半,公猪在7日龄阉割,使用商品日粮分栏饲养至100 kg左右屠宰,试验历时8个月。结果表明:去势公猪的平均背膘厚和胴体肥肉率显著高于母猪,而胴体瘦肉率、皮率和骨率极显著低于母猪;去势公猪的pH24、亮度、红度、黄度和肌内脂肪含量极显著高于母猪,大理石花纹显著优于母猪;去势公猪背最长肌的肌纤维细胞面积极显著低于母猪,而皮下脂肪细胞面积极显著大于母猪;去势公猪成脂基因PPARγ、aP2和SCD表达水平显著高于母猪,而脂解基因ATGL的表达水平极显著低于母猪。以上结果表明,关中黑猪去势公猪的肉品质优于母猪,但胴体品质低于母猪,去势公猪脂肪含量高于母猪与其成脂能力强和脂解能力弱有关。     

去势对公猪生长性能和胴体品质的影响

试验选用40头新生仔公猪,由5头健康母猪哺乳,每头母猪哺乳去势和完整仔公猪各4头。保育期开始分别饲养,记录全程的采食量和各阶段体重;分别于20、38、85、135和185日龄采集每头猪的粪便和血液样品,用于测定粪臭素和吲哚的含量;并分析血清中雄烯二酮、睾酮(T)、三碘甲腺原氨酸(T3)和生长激素(GH)水平;育肥末屠宰并分析胴体品质。结果显示,去势对猪的日增重无显著影响(P>0.05)。完整公猪平均背膘厚和肌内脂肪含量低于去势公猪(P<0.05);完整公猪脂肪中粪臭素和吲哚水平、血清中雄烯二酮水平高于去势公猪(P<0.05)。185日龄时,完整公猪血清中生长激素水平明显高于去势公猪(P<0.05)。各个日龄完整公猪血清中睾酮水平均极显著高于去势公猪(P<0.01)。结论:去势并不显著影响公猪的生长速率,但显著增加了背膘厚和肌内脂肪含量;完整公猪脂肪和血清中粪臭素和吲哚水平,血清中雄烯二酮水平均显著高于去势公猪。     

初情期前母猪垂体细胞LH和FSH的释放及其对GnRH类似物的反应

利用垂体细胞单层培养模型研究了30，60，90，120和150日龄北京黑猪母猪垂体细胞LH和FSH的释放及其对LRH－A3反应能力。结果表明，猪垂体细胞LH和FSH释放对LRH－A3的反应呈S形剂量依赖型同线。LH基础释放量和LRH－A3刺激的最大释放量在不同日龄间没有显著差异，说明初情期前母猪垂体细胞已达最大LH释放和对GnRH反应的能力。FSH的基础释放量和LRH－A3刺激的最在释放量在30日龄与60日龄之间无差异，但90日龄以后垂体细胞FSH的释施量随日龄增大而降低，提出可能由于垂体在体内时受过抑制素的作用。     

香猪生殖器官的发育及血浆雌二醇和睾酮含量变化

测试验定了初生、10、20、30、90、150和210日龄香猪公母猪的生殖器官及其血浆雌二醇和睾酮浓度。结果表明,香猪公猪的生殖器官发育较早,母猪生殖器官发育较迟。90日龄时,公猪睾酮水平达3273±1455pg/ml,母猪雌二醇水平也开始上升。发现公猪血浆中查得较母猪高的雌二醇水平。     

江泉黑猪生长发育规律及其生长曲线拟合研究

为探讨江泉黑猪的生长发育规律,本研究测定了江泉黑猪60～240日龄的体重变化,采用Logistic模型、Gompertz模型和von Bertal anffy模型对江泉黑猪体重进行生长曲线拟合研究。结果发现,3种模型拟合效果均较好,拟合度均大于0.99。为了进一步研究江泉黑猪的最优拟合模型,将3种模型拟合值与实测值进行对比分析,结果发现von Bertal anffy模型更符合江泉黑猪生产实际。von Bertal anffy模型对江泉黑猪体重拟合结果显示,江泉黑猪母猪和公猪的拟合度均为0.997,江泉黑猪母猪成熟体重估计值为178.095 kg,拐点体重为52.77 kg,拐点日龄为113.13 d,最大日增重633.23 g;江泉黑猪公猪成熟体重估计值为182.329 kg、拐点体重为54.02 kg,拐点日龄为115.38 d,最大日增重为648.28 g。本研究为江泉黑猪的进一步选育及开发利用提供了参考依据。     

早期断奶并补饲代乳粉对羔羊生长性能、消化性能、血清生化指标及肉品质的持续影响

本试验旨在研究早期断奶并补饲代乳粉对羔羊生长性能、消化性能、血清生化指标及肉品质的持续影响。选取60只体重[(8.26±2.14) kg]、日龄[(20±1)日龄]相近的健康湖羊公羔,随机分成随母哺乳组(ER组)和早期断奶组(EW组),每组6个重复,每个重复5只羔羊。ER组羔羊饲喂母乳+开食料,至60日龄断母乳;EW组羔羊饲喂代乳粉+开食料,至开食料采食量达到300 g/d时停止饲喂代乳粉。所有羔羊从20日龄开始补饲开食料至65日龄,之后过渡至育肥颗粒料。羔羊65日龄前每隔10 d称重,65日龄后每隔30 d称重;在羔羊65、120、180日龄晨饲前颈静脉采血测定血清生化指标;在55～65日龄、115～125日龄、170～180日龄阶段,每个重复选取1只(共12只)羊进行消化代谢试验;在180日龄,每个重复选取1只(共12只)羊屠宰测定肉品质。结果显示:1) EW组羔羊46～55日龄阶段平均日增重显著低于ER组(P0.05),91～120日龄阶段平均日增重显著高于ER组(P0.05)。2) EW组羔羊55～60日龄、115～125日龄、170～180日龄阶段各营养物质消化率相较ER组均未出现显著差异(P0.05)。3)EW组羔羊65、120日龄时血清尿素氮、生长激素含量显著高于ER组(P0.05),EW组羔羊180日龄时血清β-羟丁酸含量显著低于ER组(P0.05)。4)早期断奶并补饲代乳粉对羔羊180日龄宰前活重、屠宰率及肉品质指标均无显著影响(P0.05)。综上所述,早期断奶并补饲代乳粉降低了羔羊哺乳阶段(25～65日龄)的生长性能,但提高了育肥前期(66～120日龄)羔羊的生长性能,对育肥后期(121～180日龄)羔羊的生长性能、消化性能及肉品质均没有显著影响。     

鲁西黑猪生长发育性状测定与分析

对鲁西黑猪原种场初生至8月龄的31头公猪和62头母猪的生长发育性状进行了测定,并在不同生长阶段屠宰后进行组织器官的分离测定。结果表明:鲁西黑猪体重和体尺等指标在4月龄前公、母无显著差异,5月龄后母猪体重和体尺逐渐大于公猪。增重高峰公、母猪均在5~6月龄。胴体组织早熟顺位为骨骼—皮肤—肌肉—脂肪,体躯各段早熟顺位是四肢—头—腰—腿臀—颈胸。鲁西黑猪不同器官的早熟性反映了其生长发育的内在素质。     

Changes in the serum concentrations of gonadotrophins and oestradiol in peripubertal Chinese Beijing Black gilts

Four gilts of the Chinese Beijing Black breed, all from the same litter, had their blood serum concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH) and oestrogens (E₂) measured by radioimmunoassay at intervals of 20 days between the ages of 5 and 185 days. The concentrations of LH declined sharply between days 5 to 25 and remained low until rising again from day 85 and reaching a peak at day 105 before declining again and remaining constant. The concentrations of FSH increased from day 85, peaking at day 105, followed by a slow decline to day 185. Serum E₂ concentrations were high at day 5 then decreased dramatically, but increased considerably at 185 days. These results are similar to those reported from European breeds.Abbreviations CV coefficient of variation - E₂ oestrogens - FSH follicle stimulating hormone - IU international unit - LH luteinizing hormone - RIA radioimmunoassay     

Plasma prolactin, LH, FSH and estrogen excretion patterns in gilts during sexual development

Plasma prolactin (PRL), luteinizing hormone (LH) and follicle stimulating hormone (FSH) were measured by radioimmunoassay in groups of eight gilts sampled every 20 min for 6 h at about 2-wk intervals between 15 and 192 d of age. The PRL levels were high at 15 and 28 d, declined at 40 d just after weaning and then rose slowly until 192 d of age. The number of LH pulses during 6 h was higher between 83 and 125 d than at the other periods. Magnitude of LH pulses was highest at 15 d, constant from 54 to 125 d, fell at 137 d and remained low until 192 d. Plasma FSH was high from 15 to 125 d, with a maximum at 54 d. It declined slowly until 168 d and did not change thereafter. Estrogen excretion was estimated from urine excretion of estrone (E1; conjugated plus nonconjugated E1) per 24 h from 40 d until puberty in three gilts and at 156 and 174 d in two other animals. The E1 excretion increased with age and four levels were described before peak values with the onset of first estrus. The first increase in E1 excretion occurred between 68 and 110 d, when antral follicles appeared in the ovaries. It was subsequent to the highest levels of FSH and concomitant with the increased frequency of LH pulses. The drop in levels of both gonadotropins after 125 d probably corresponded to the development of the negative feedback as a result of greater ovarian activity in these gilts.     

Correlated response to selection for litter size in pigs: I. Growth,fat deposition,and feeding behavior traits

Data on individually tested pigs from a line selected for litter size (H) and a control line (C) were used to estimate the correlated responses to litter size in growth, fat, and feeding behavior patterns from 75 to 165 d of age. During the test period, BW and ultrasonic midback (UMB) and loin (ULB) backfat were recorded periodically on the same animal. Individual voluntary feed intake (DFI), number of visits (NVD), and feeding time (FTD) were measured on a daily basis using an automatic feeding system. Third degree polynomial models with random regression coefficients were used to describe BW, UMB, ULB, DFI, NVD, and FTD as a function of age. The first derivative of the model for BW was used to estimate growth rate. Several measurements of efficiency were obtained using polynomial models on accumulated DFI, NVD, and FTD. The difference between the genetic means of animals from line H and line C was used to estimate correlated responses. The H pigs showed higher BW throughout most of the test period (2.29 +/- 0.90 kg at 135 d of age, P < 0.05) but they were not different (P = 0.18) from C pigs at the end of the test (102 kg, SD 9). Thus, despite both lines showing similar average growth rate on the test, line H grew faster at the start of the test (34 +/- 11 g/d, P < 0.01), but it grew more slowly by the end (-68 +/- 27 g/d, P < 0.05). Fat deposition rate differed between lines, with H pigs showing higher UMB (1.26 +/- 0.23 mm, P < 0.01) and ULB (1.32 +/- 0.28 mm, P < 0.01) at 165 d of age. The difference between lines in total on-test feed intake was not significant (P= 0.10), but intake was slightly higher in line H between 105 and 135 d of age (2.28 +/- 1.25 kg, P = 0.07). Line H showed a higher feed efficiency up to about 100 d of age, whereas line C performed better from this age until 165 d of age. However, differences never exceeded 18 +/- 6 g of weight gain per kilogram of feed consumption (P < 0.01). Total feed efficiency throughout the test period was slightly higher in line C (1.37 +/- 0.77 kg of weight gain after eating 185 kg of feed, P = 0.08). Lines H and C had distinct feeding patterns with regard to eating frequency. Pigs from line H ate less frequently, but instead they spent more time and ate more per visit. In the long term, selection for litter size could result in pigs with less capacity of lean growth.     

内蒙古阿尔巴斯绒山羊胎儿期皮肤毛囊发生发育规律研究

以阿尔巴斯绒山羊胎儿期55d至初生10个阶段的头顶、颈侧、髫甲、颈上缘、肩胛、体侧、背部、荐部、股部、腹部10个部位皮肤为样品，制作横切和纵切切片，观测皮肤毛囊性状的发育规律。结果表明：各部位表皮在胎龄55～65d均形成完整的结构，在胎龄85～95d达到最厚；真皮厚度在胎龄95～125d增长幅度较大。胎龄55d见到初级毛囊原始体，胎龄65d见到次级毛囊原始体，次级毛囊是初级毛囊的一个分支。胎龄85d见到皮脂腺，胎龄95d绒、毛开始形成，见到汗腺，有粗毛长出体表，绒毛在胎龄115d长出体表。各部位初级毛囊在胎龄95～115d增长速度较快，次级毛囊在胎龄105～125d增长速度较快；初级毛囊密度在胎龄75～85d最大，次级毛囊密度在胎龄105～125d达到最大，S／P在胎龄115d至初生时达到最大。胎龄105d已经形成完整的毛囊群结构，主要为三元毛囊群。     

Neuroendocrine Regulation of Growth Hormone and Luteinizing Hormone in Fetal and Neonatal Pig

Ontogeny of the production and the regulation of growth hormone and Luteinizing hormone is studied in a series of experiments utilizing male and female pigs at different fetal and neonatal stages. Growth hormone mRNA is detectable in both sexes as early as d. 50 p.c. The mRNA levels increase to reach the maximum levels at d. 95–110 p.c. Plasma levels of GH follow the developmental patterns of GH mRNA. A sex difference is evident around d. 80–90 p.c. with males having higher GH levels than females. The stimulatory but not the inhibitory mechanisms of GH secretion are fully functioning in the pig fetus. LHβ mRNA is detectable earlier in females (d. 50 p.c.) than in males (d. 65 p.c.). Plasma concentrations of LH increase with fetal age in female fetuses, but in male fetuses there is no distinct developmental pattern evident. Basal LH secretion achieves maximum levels in both sexes after birth. Opioids do modulate fetal LH secretion, however, the mode of their action is age-dependent.     

Few differences found between early- and late-weaned pigs raised in the same environment

Segregation and medicated early weaning are technologies used to optimize the productivity and health of pigs, but these practices may also cause aberrant behaviors indicative of stress. Thus, differences in early- (=10 d of age) and late- (=30 d of age) weaned pigs were investigated. At weaning, pigs were housed in groups of four in 16 pens (eight pens per treatment) in the same facility, and, thus, they were not segregated. Body weights were recorded at birth, weaning, and at approximately 42, 65, 102, 137, and 165 d of age (at slaughter). One-minute, instantaneous scan samples during a 10-min period (at 0600, 1000, 1400, and 1800) were used to record the frequency of lying, standing, and sitting, total number of drinks, feeder investigations, and time spent playing/fighting on 2, 3, and 4 d after weaning. Five-minute, direct observations of each pig were conducted at approximately 40, 60, 80, and 150 d of age. Direct observations were also made of the entire pen for 10 min at approximately 50, 95, 123, and 160 d of age to record aberrant behaviors. At 62 d of age, a handling and blood collection stress was imposed. At 165 d of age, a second stress test was conducted in response to rough handling and transport. Early-weaned pigs spent more time playing/ fighting (P < .006) than late-weaned pigs during the 4 d after weaning, manipulated conspecifics more often at 40 d of age (P < .002), had greater percentage of hemoglobin (P < .03) during Stress Test 1, had greater ADG at 42 d of age (P < .03), and had greater hypothalamic growth hormone-releasing hormone receptor mRNA at slaughter (P < .06). Late-weaned pigs had greater ADG between 137 and 165 d of age (P < .03) and greater pro-opiomelanocortin at slaughter (P < .04). Overall, most differences found between early-weaned and late-weaned pigs were evident soon after weaning, but they disappeared before slaughter.     

Serum leptin concentrations, luteinizing hormone and growth hormone secretion during feed and metabolic fuel restriction in the prepuberal gilt

Two experiments were conducted to determine 1) the effect of acute feed deprivation on leptin secretion and 2) if the effect of metabolic fuel restriction on LH and GH secretion is associated with changes in serum leptin concentrations. Experiment (EXP) I, seven crossbred prepuberal gilts, 66 +/- 1 kg body weight (BW) and 130 d of age were used. All pigs were fed ad libitum. On the day of the EXP, feed was removed from four of the pigs at 0800 (time = 0) and pigs remained without feed for 28 hr. Blood samples were collected every 10 min from zero to 4 hr = Period (P) 1, 12 to 16 hr = P 2, and 24 to 28 hr = P 3 after feed removal. At hr 28 fasted animals were presented with feed and blood samples collected for an additional 2 hr = P 4. EXP II, gilts, averaging 140 d of age (n = 15) and which had been ovariectomized, were individually penned in an environmentally controlled building and exposed to a constant ambient temperature of 22 C and 12:12 hr light: dark photoperiod. Pigs were fed daily at 0700 hr. Gilts were randomly assigned to the following treatments: saline (S, n = 7), 100 (n = 4), or 300 (n = 4) mg/kg BW of 2-deoxy-D-glucose (2DG), a competitive inhibitor of glycolysis, in saline iv. Blood samples were collected every 15 min for 2 hr before and 5 hr after treatment. Blood samples from EXP I and II were assayed for LH, GH and leptin by RIA. Selected samples were quantified for glucose, insulin and free fatty acids (FFA). In EXP I, fasting reduced (P < 0.04) leptin pulse frequency by P 3. Plasma glucose concentrations were reduced (P < 0.02) throughout the fast compared to fed animals, where as serum insulin concentrations did not decrease (P < 0.02) until P 3. Serum FFA concentrations increased (P < 0.02) by P 2 and remained elevated. Subcutaneous back fat thickness was similar among pigs. Serum IGF-I concentration decreased (P < 0.01) by P 2 in fasted animals compared to fed animals and remained lower through periods 3 and 4. Serum LH and GH concentrations were not effected by fast. Realimentation resulted in a marked increase in serum glucose (P < 0.02), insulin (P < 0.02), serum GH (P < 0.01) concentrations and leptin pulse frequency (P < 0.01). EXP II treatment did not alter serum insulin levels but increased (P < 0.01) plasma glucose concentrations in the 300 mg 2DG group. Serum leptin concentrations were 4.0 +/- 0.1, 2.8 +/- 0.2, and 4.9 +/- 0.2 ng/ml for S, 100 and 300 mg 2DG pigs respectively, prior to treatment and remained unchanged following treatment. Serum IGF-I concentrations were not effected by treatment. The 300 mg dose of 2DG increased (P < 0.0001) mean GH concentrations (2.0 +/- 0.2 ng/ml) compared to S (0.8 +/- 0.2 ng/ml) and 100 mg 2DG (0.7 +/- 0.2 ng/ml). Frequency and amplitude of GH pulses were unaffected. However, number of LH pulses/5 hr were decreased (P < 0.01) by the 300 mg dose of 2DG (1.8 +/- 0.5) compared to S (4.0 +/- 0.4) and the 100 mg dose of 2DG (4.5 +/- 0.5). Mean serum LH concentrations and amplitude of LH pulses were unaffected. These results suggest that acute effects of energy deprivation on LH and GH secretion are independent of changes in serum leptin concentrations.     

Effects of dietary salt level during gestation and lactation on reproductive performance of sows: a cooperative study

Two experiments involving 1,020 litters were conducted at eight research stations to determine the effects of dietary NaCl (salt) concentration during gestation and lactation on reproductive performance of sows. Primiparous and multiparous sows were fed fortified corn- or grain sorghum-soybean meal diets at 1.82 kg/d during gestation. During the winter months (December, January, February) the feeding level was increased to 2.27 kg/d. Sows had ad libitum access to diets during lactation. Dietary concentrations of added salt were .50 and .25% in Exp. 1 and .25 and .125% in Exp. 2. When more feed was fed during gestation, the salt concentrations were reduced to .40, .20, .20 and .10%, respectively, in order to maintain a constant daily intake of Na and Cl during gestation. Gestation weight gain and lactation (21-d) weight loss of the sows were not affected by dietary salt level in either experiment. In Exp. 1, lowering the salt concentration did not influence the number of pigs farrowed, but it resulted in a .05 kg/pig reduction (P less than .01) in average birth weight. Average 21-d pig weights also tended (P less than .19) to be lower in the low-salt group. There was a decrease in litter size from the first to the second farrowing for sows fed low salt, but not for sows fed the higher salt concentration. In Exp. 2, reducing the salt content from .25 to .125% did not alter reproductive performance. The overall ratio of males to females at birth in the population of greater than 10(4) pigs was 52.3:47.7. Lower salt intakes tended to reduce the percentage of males born in both experiments, although the differences were not significant (P greater than .3). The results indicate that reducing the salt concentration in sows diets from .50 to .25 or .125% reduces birth weight in newborn pigs. When continued for more than one reproductive cycle, feeding less than .5% salt appears to reduce litter size at birth and weaning.     

Temperature and body weight affect fouling of pig pens

Fouling of the solid lying area in pig housing is undesirable for reasons of animal welfare, animal health, environmental pollution, and labor costs. In this study the influence of temperature on the excreting and lying behavior of growing-finishing pigs of different BW (25, 45, 65, 85, or 105 kg) was studied. Ten groups of 5 pigs were placed in partially slatted pens (60% solid concrete, 40% metal-slatted) in climate respiration chambers. After an adaptation period, temperatures were raised daily for 9 d. Results showed that above certain inflection temperatures (IT; mean 22.6 degrees C, SE = 0.78) the number of excretions (relative to the total number of excretions) on the solid floor increased with temperature (mean increase 9.7%/ degrees C, SE = 1.41). Below the IT, the number of excretions on the solid floor was low and not influenced by temperature (mean 13.2%, SE = 3.5). On average, the IT for excretion on the solid floor decreased with increasing BW, from approximately 25 degrees C at 25 kg to 20 degrees C at 100 kg of BW (P < 0.05). Increasing temperature also affected the pattern and postural lying. The temperature at which a maximum number of pigs lay on the slatted floor (i.e., the IT for lying) decreased from approximately 27 degrees C at 25 kg to 23 degrees C at 100 kg of BW (P < 0.001). At increasing temperatures, pigs lay more on their sides and less against other pigs (P < 0.001). Temperature affects lying and excreting behavior of growing-finishing pigs in partially slatted pens. Above certain IT, pen fouling increases linearly with temperature. Inflection temperatures decrease at increasing BW.