Evaluation of growth, carcass traits and reproductive organs of young boars in response to zeranol implantation

Two experiments were conducted to evaluate the effect of implants containing zeranol on growth rate, carcass composition, palatability and reproductive organ development of intact male pigs. In Exp. 1, three treatment groups were evaluated: control barrows, intact control boars and implanted boars (implanted at either 28, 56 or 112 d of age with one 12-mg dose of zeranol). In Exp. 2, four treatment groups were evaluated: control barrows, intact control boars, boars implanted at 28 d with 24 mg of zeranol (single implant) and boars implanted at 28 d and re-implanted at 56 and 112 d of age with 24 mg of zeranol (triple implant). Differences for average daily gain and carcass traits were not consistent between treatment groups with the exception of 10th rib fat, where barrows were fatter than boars. There were no differences among treatments due to zeranol for the reproductive organ characteristics, with the exception that bulbourethal gland and teat weights were heavier for boars in Exp. 2. Penis weights and lengths were lower for barrows in both experiments. Juiciness, tenderness, Warner-Bratzler shear force, pork flavor intensity and sensory scores were not consistently affected by male condition or zeranol treatment. In two of the three comparisons, implanted boars had higher off-flavor intensity scores in Exp. 1, but no treatment difference was observed in Exp. 2. Zeranol implantation did not result in significant changes in growth rate, development of reproductive organs or carcass characteristics of young boars.     

Age‐related changes in semen quality characteristics and expectations of reproductive longevity in Duroc boars

Quadratic fitting was used to regress semen characteristics of 1441 samples consisting of 12‐month collection from 58 Duroc boars against animal age varied from 10 to 80 months. Data was divided into two groups of cool (14.0–22.7°C, RH 81.5%) and hot season (22.9–29.9°C, RH 86.6%), to test effects of age, season and their interactions. Results revealed that young boars of around 1 year old could endure the hot season. The endurance gradually diminished as animals grew. In the hot season animals exhibited peak performance at age around 33 month and it remained for 1 month, while cool‐season kept boars could last for 48 months from 16 months old onward. The reproductive longevity should be 51 month in a subtropical environment and it may extend to 70 month if heat stress can be avoided. The estimated total sperm contribution of a Duroc boar would be 1.8 times more when kept below 22°C than in a natural subtropical environment. It is concluded that to maintain Duroc boars as semen donor to at least 4 years of age is feasible in a subtropical environment and boar longevity could reach 6 years old if well kept in a temperate region.     

种公猪营养与繁殖性能

营养与繁殖性能的关系越来越受到人们关注,而种公猪的繁殖性能对养猪生产至关重要。研究表明营养是影响种公猪繁殖性能的主要因素,营养缺乏使得种公猪繁殖性能低下。文中主要综述了能量、蛋白质与氨基酸、维生素、矿物质等营养素与种公猪繁殖性能关系以及种公猪的营养需要等。     

The use of ultrasonography in the reproductive evaluation of boars

The objective was to study the use of ultrasound as a complementary test in the breeding soundness evaluation in male pigs and study the pattern of echogenicity of the testicular parenchyma in boars of different racial groups. Twenty‐six adult boars from four different racial groups were used, 10 from the Piau breed (group 1), four from the commercial and finishing group (group 2), six Pietrain breed (group 3) and six from the Duroc breed (group 4). All animals were evaluated for breeding soundness evaluation and the ultrasound examination of the testicles. The groups of animals that were evaluated showed no difference in the main semen parameters that were evaluated, except for the sperm volume, concentration of the ejaculated sperm and the supravital staining; the lowest figures were for the animals from the Piau breed (group 1). In relation to the testicular biometrics, Duroc animals (group 4) had a greater scrotal width compared to the other groups. But when we assessed the intensity of pixels of the testicles, there was a difference between groups. The groups 2 (finishing animals), 3 (Pietrain) and 4 had no difference between themselves. Group 3 had greater pixel intensity in relation to group 1. Of the 26 animals studied, five showed an abnormality during ultrasound evaluation, like hydrocele, hyperechoic mass in the testicular parenchyma, cyst in the head of the epididymis and the presence of fluid in the head and tail of the epididymis. The various animal groups studied did not differ in the principal reproductive parameters evaluated, showing that despite the great variability of reproductive traits between breeds and within the same breed, the breeding soundness evaluation, the more complete it is, is essential for the selection of breeders and the ultrasonography of the reproductive system becomes an important addition in this examination.     

Seminal changes in boars after heat stress

The object of the present study was to investigate the influence of elevated ambient temperature on sperm production, sperm morphology and composition of seminal plasma in boars. A total of 8 boars were used, 4 of them were exposed to 35°C, in a climate room, during 100 h and 4 served as controls and were kept at 20°C during 100 h in the climate room.Ejaculate volume and total sperm count per ejaculate remained unaltered. An obvious decrease in sperm motility was seen in all heat exposed boars 15–21 days after the exposure. The most consistent increase in sperm abnormalities were proximal cytoplasmic droplets and abnormal sperm heads. The highest levels were found during the 4th week after exposure. All the sperm characteristics assessed had returned to normal levels at the end of the experimental period, which means 7–8 weeks after the end of exposure.Only minor and inconsistent alterations were found in the seminal plasma components analysed and these changes were observed both in control and experimental boars.     

葡萄糖氧化酶对公猪生殖性能的影响

为探讨葡萄糖氧化酶对种公猪生殖性能的影响,选择18～24月龄、体重150～200 kg健康长白种公猪25头,分为5组,每组5个重复.对照组饲喂基础日粮,试验1、2、3、4组分别在基础日粮中添加1、2、3、4kg/t的葡萄糖氧化酶.试验期28 d.结果表明:试验3、4组公猪血清中雌二醇含量显著高于对照组(P＜0.05),...     

Experimentally induced testicular alterations in boars: hormonal changes in mature and peripubertal boars

Eleven sexually mature boars and 10 peripubertal boars were used to study the effects of elevated testicular temperature on plasma hormonal levels. The scrotum of the boars was covered with a textile-aluminium foil insulation device for 100 h. Insulation of the scrotum in the peripubertal boars took place at an age of 100 days. Blood samples were drawn 3 times daily for 12 days in the mature boars, starting 3 days before scrotal insulation. In the peripubertal boars, blood sampling was performed once a day for 11 days, starting the first day of scrotal insulation. During scrotal insulation, the plasma levels of testosterone, oestradiol-17 beta and oestrone sulphate decreased continuously in the mature boars. After removal of the scrotal insulation device there was a continuously increase, back to normal levels of oestradiol-17 beta and oestrone sulphate. The plasma levels of testosterone showed an immediate rise of brief duration after removal of the device in 5 of the boars, while in the other 6 boars the rise in testosterone levels came 4 days after removal and lasted for 3 days. In the peripubertal boars, there were no significant differences in the hormone levels between the experimental and control animals during and after scrotal insulation. However, the decrease in testosterone concentration over time, during scrotal insulation, was significant within the experimental group.     

Effects of soybean isoflavones on reproductive parameters in Chinese mini-pig boars

Background: Soybean isoflavones are structurally similar to mammalian estrogens and therefore may act as estrogen agonists or antagonists. However, it has not been determined if they have any negative effects on reproductive parameters in male livestock. Therefore, the objective of this study was to evaluate the effects of soybean isoflavones on male reproduction using Chinese mini-pig boars as a model. Fifty Xiang boars were randomly divided into five groups and fed diets containing 0, 125, 250, or 500 ppm soybean isoflavones or 0.5 ppm diethylstilbestrol for 60 days. Results: Dietary supplementation with 250 ppm of soy isoflavones markedly increased the testis index (P<0.05), fructose content (P <0.05), and α-glycosidase content in testicular tissue (P<0.01), as well as increased the number of viable germ cells (P<0.01) and the level of Bcl-2 protein (P <0.01). However, 500 ppm of soybean isoflavones significantly reduced both testis and epididymis indexes (P<0.05) and lactate dehydrogenase levels (P<0.01), as well as reduced serum LH and testosterone levels (P<0.05). High levels of soybean isoflavones also increased malondialdehyde levels (P<0.05), as well as increased the numbers of early and late apoptotic germ cells (P<0.01) and the level of Bax proteins (P<0.05) in the testis. Conclusions: The results of this study indicate that consumption of soy isoflavones at dietary levels up to 250 ppm did not adversely affect reproductive parameters in Chinese mini-pig boars whereas higher levels of soy isoflavones may adversely affect male reproduction.     

Effects of soybean isoflavones on reproductive parameters in Chinese mini-pig boars

Background

Soybean isoflavones are structurally similar to mammalian estrogens and therefore may act as estrogen agonists or antagonists. However, it has not been determined if they have any negative effects on reproductive parameters in male livestock. Therefore, the objective of this study was to evaluate the effects of soybean isoflavones on male reproduction using Chinese mini-pig boars as a model. Fifty Xiang boars were randomly divided into five groups and fed diets containing 0, 125, 250, or 500 ppm soybean isoflavones or 0.5 ppm diethylstilbestrol for 60 days.

Results

Dietary supplementation with 250 ppm of soy isoflavones markedly increased the testis index (P < 0.05), fructose content (P < 0.05), and α-glycosidase content in testicular tissue (P < 0.01), as well as increased the number of viable germ cells (P < 0.01) and the level of Bcl-2 protein (P < 0.01). However, 500 ppm of soybean isoflavones significantly reduced both testis and epididymis indexes (P < 0.05) and lactate dehydrogenase levels (P < 0.01), as well as reduced serum LH and testosterone levels (P < 0.05). High levels of soybean isoflavones also increased malondialdehyde levels (P < 0.05), as well as increased the numbers of early and late apoptotic germ cells (P < 0.01) and the level of Bax proteins (P < 0.05) in the testis.

Conclusions

The results of this study indicate that consumption of soy isoflavones at dietary levels up to 250 ppm did not adversely affect reproductive parameters in Chinese mini-pig boars whereas higher levels of soy isoflavones may adversely affect male reproduction.     

小尾寒羊同期发情技术优化及其血清生殖激素的变化

为了优化绵羊同期发情技术,本试验分析了不同外源激素对小尾寒羊的同期发情效果,并进行生殖激素测定。将80只健康、空怀的经产小尾寒羊随机分为2组,每组4个重复,每个重复10只。采用单因素设计,分别用CIDR+PMSG、PG+PMSG进行同期发情处理,并在处理期间每组随机抽取4只小尾寒羊空腹颈静脉采血,采用放射免疫法测定血清中雌二醇(E2)、孕酮(P4)、促黄体素(LH)、促卵泡素(FSH)的浓度。结果表明:CIDR+PMSG组小尾寒羊同期发情率、受胎率分别为82.50%、75.00%,均显著高于PG+PMSG处理组(P0.05);CIDR+PMSG组小尾寒羊颈静脉血液中E2浓度在撤栓24 h上升至峰值(8.64±0.13)pg/m L,显著高于撤栓时、撤栓48 h的浓度(P0.05),P4浓度在撤栓7d显著高于撤栓24 h、撤栓48 h(P0.05),LH、FSH浓度变化曲线与E2相似,都是在撤栓24 h显著升高;PG+PMSG组除LH在二次注射后的第2天、第3天显著升高(P0.05),其余3种激素浓度差异不显著(P0.05)。总之,与PG+PMSG相比,CIDR+PMSG可以显著提高小尾寒羊同期发情效率,并且发情高峰期在撤栓后的24 h前后,因此,人工输精选择在撤栓后12h~36h之间进行为佳。     

Pathological changes in the lumbar spine of boars.

Lumbar vertebral columns from 73 boars were examined for pathological changes. While pathological changes were minimal at five months of age, several animals aged seven to 18 months of age had facet asymmetry and large osteophytes surrounding lumbar facets. In the adult group 36% had degeneration of intervertebral discs and 28% had ventrolateral vertebral osteophytes. Lesions characterized by irregular areas of cavitation in the annulus and adjacent vertebral epiphyses were also observed. Of animals submitted for necropsy with a history of clinical lameness. lesions included nonsuppurative polyarthritis, fracture of the sacrum and femoral head, osteochondrosis involving articular cartilage of the distal humerus and distal femur, vertebral osteomyelitis, meningeal abscess and ulnar osteomyelitis.     

种公猪的营养需要及营养对种公猪繁殖性能的影响

种公猪的繁殖力不仅直接决定公猪站的经济效益,而且也直接影响规模化猪场母猪的繁殖性能。种公猪的繁殖力受多种因素的影响,营养是其中的重要因素之一。本文就国内外关于种公猪营养的文献报道,针对营养对种公猪繁殖性能的影响及种公猪的营养需要做较为全面的综述,为生产上公猪的日粮配比提供参考。     

Age-related changes in the testes of horses

Atrophy of seminiferous tubules and interstitial fibrosis are frequently observed in aged horses. Samples from 8 male Thoroughbreds, age 4-24 years, were subjected to histological, electron microscopical and immunohistochemical examination and statistical analysis. There were statistically significant increases in collagen fibres in the lamina propria of seminiferous tubules and testicular interstitium in 3 horses age 23 and 24 years compared with 5 horses age 4-20 years (P<0.001). Lamina propria surrounding atrophic tubules was thickened by an increase in collagen type IV and elastic fibres and by proliferation of bizarre myoid cells. Basal lamina was also thickened but had decreased reactivity for collagen type IV. Some myoid cells changed morphologically to a swollen and irregular shape and contained abundant cytoplasmic organelles. Laser scanning microscopy revealed that cytoplasmic actin filaments were decreased; the remaining filaments were positive for alpha-smooth muscle actin and vimentin, and matrix metalloproteinase-2 was secreted. These myoid cells transformed into myofibroblasts. The changes are interpreted as evidence of injured structure and function of the lamina propria and basal lamina and may explain the functional decline of the blood-testis barrier. Myoid cells may play an important role in the progression of testicular fibrosis.