猪氟烷基因对繁殖性能的影响初探

本文采用PCR—RFLP技术检测了德阳市种畜场“九五”期间长白猪选育群第三世代123个个体的氟烷基因型,并统计分析了其中80头母猪(NN型52头,Nn型28头)头胎繁殖性状受氟烷敏感基因(Haln)影响的情况。研究结果表明,该猪群中Haln基因的频率为13.82%;NN型个体35日龄断奶成活率显著高于Nn型个体,在其他繁殖性状上二者间无显著差异,研究结果为全面了解Haln基因的遗传效应及其合理利用提供了理论依据和参考。     

Effect of magnesium sulphate and l-tryptophan and genotype on the feed intake, behaviour and meat quality of pigs

Sixty-nine entire male pigs with different halothane genotype (homozygous halothane positive — nn-, n = 36; and homozygous halothane negative — NN-, n = 33) were fed with a supplementation of magnesium sulphate (Mg) and/or l-tryptophan (Trp) in the diet for 5 days before slaughter. Animals were housed individually and were submitted to stressful ante mortem conditions (mixed in the lorry according to treatments and transported 1 h on rough roads). Individual feed intake was recorded during the 5-d treatment. At the abattoir, pig behaviour was assessed in the raceway to the stunning system and during the stunning period by exposure to CO₂. Muscle pH, colour, water holding capacity, texture and cathepsin activities were determined to assess meat quality. The number of pigs with an individual feed intake lower than 2 kg/day was significantly different among diets (P < 0.05; Control: 8.7%; Mg&Trp: 43.5%; Trp: 17.4%) and they were considered to have inadequate supplement intake. During the ante mortem period, 15.2% of pigs included in the experiment died, and this percentage decreased to 8.7% in those pigs with a feed intake > 2 kg/day, all of them from the stress-sensitive pigs (nn). In general, no differences were observed in the behaviour of pigs along the corridor leading to the stunning system and inside the CO₂ stunning system. During the stunning procedure, Trp diet showed shorter periods of muscular excitation than control and Mg&Trp diets. The combination of a stressful ante mortem treatment and Mg&Trp supplementation led to carcasses with high incidence of severe skin lesions. Different meat quality results were found when considering all pigs or considering only those with adequate supplement intake. In this later case, Trp increased pH₄₅ (6.15) vs Control diet (5.96) in the Longissimus thoracis (LT) muscle (P < 0.05) and pH at 24 h (Trp: 5.59 vs C: 5.47) led to a higher incidence of dark, firm and exudative (DFD) traits in SM muscle (P < 0.05). Genotype affected negatively all the meat quality traits. Seventy-five percent of LT and 60.0% of the SM muscles from nn pigs were classified as pale, soft and exudative (PSE), while none of the NN pigs showed these traits (P < 0.0001). No significant differences were found between genotypes on the incidence of DFD meat.Due to the negative effects observed in the Mg&Trp group in feed intake and carcass quality, the utilization of a mixture of magnesium sulphate and tryptophan is not recommended.     

乙酸镁对氟烷基因杂合子育肥猪肌肉加工品质的影响

育肥猪屠宰前饲粮中短期添加乙酸镁,研究其对氟烷基因杂合子育肥猪肌肉加工品质的影响。选用体重相近的氟烷基因杂合子(HalNHaln)大长猪(大白猪×长白猪)36头随机分为2组,即对照组、乙酸镁组,每组18头。乙酸镁组在屠宰前5 d,基础日粮中添加镁1 500mg/kg(以乙酸镁形式),对照组饲喂基础日粮。试验表明:在猪屠宰前饲粮中短期添加1 500 mg/kg水平的镁对试验猪的平均日采食量没有明显影响(P>0.05);可以显著降低肌肉的滴水损失(P<0.05),提高猪肉的熟肉率,从而提高猪肉的加工品质。     

Effect of supplementation with MgCO3 and l-Tryptophan on the welfare and on the carcass and meat quality of two halothane pig genotypes (NN and nn)

Sixty-one animals with different Halothane genes (homozygous halothane positive, n = 34; and homozygous halothane negative, n = 27) were fed with three diets (control group, with no supplement; magnesium (Mg) group with 1.28 g MgCO₃/kg and tryptophan (Trp) group with 5 g l-Trp/kg) during the last 5 days before slaughter. Animals were submitted to minimal stress antemortem conditions. Pig behaviour was recorded at the experimental farm, raceway to the CO₂ stunning system and during the stunning period. Corneal reflexes were recorded after stunning as well. There were no differences in feed intake among diets (P > 0.05) during the 5 days of treatment. The halothane positive (nn) group had lower intake than the halothane negative (NN) group (P < 0.01). The behaviour of the pigs in the raceway did not differ (P > 0.05) among treatments or halothane genotype. A significant (P < 0.001) interaction diet  halothane was found in the time to appear the first retreat attempt during the exposure to the CO₂ system. In the nn group, the time of performing the first retreat attempt was later in the Mg (P < 0.05) than the control group. Moreover, in the Mg group, the nn had a later (P < 0.05) first retreat attempt than the NN. Thus, Mg supplementation could have a positive effect on welfare of nn pigs. The nn had a lower proportion of animals that showed corneal reflexes after stunning than NN, indicating a higher effectiveness of the stunning method in nn pigs. Neither Mg nor Trp affected carcass quality and meat quality parameters, although significant differences were found between genotypes.     

Effects of Carbon Dioxide Insufflation and Body Position on Blood Gas Values in Horses Anesthetized for Laparoscopy

The objective of the study was to describe the effects of carbon dioxide pneumoperitoneum and Trendelenburg position on arterial blood gas values in horses anesthetized for laparoscopy. The study design was a prospective case series using 14 healthy adult horses anesthetized for elective laparoscopic surgery. All horses in the study were maintained under anesthesia with halothane in oxygen with intermittent positive-pressure ventilation. A pneumoperitoneum of 15 mmHg or less was achieved with carbon dioxide, and horses were tilted to a 35-degree Trendelenburg position to allow the completion of laparoscopic cryptorchidectomy (n = 13) or ovariectomy (n = 1). Heart rate, mean arterial pressure, and arterial blood gases were recorded at six time intervals throughout the procedure. Results of the study indicated a pH that decreased and partial pressure of carbon dioxide (PaCO₂) and mean arterial pressure that increased over time and differed significantly from baseline during Trendelenburg position. Partial pressure of oxygen (PaO₂) was significantly lower than baseline after assumption of Trendelenburg position and did not improve on return to normal recumbency and abdominal pressure. As body weight increased, pH and PaO₂ decreased and PaCO₂ increased. We concluded that horses placed in Trendelenburg position have changes that are transient, with the exception of PaO₂. Heavier horses have a greater change in pH, PaCO₂, and PaO₂ than lighter horses during abdominal insufflation and Trendelenburg position. The changes incurred during CO₂ abdominal insufflation and Trendelenburg position are transient, with the exception of a decreased PaO₂. Heavy horses undergoing abdominal insufflation and Trendelenburg position should be closely monitored for critical cardiopulmonary values.     

Diminished expression of ACTH signaling proteins and steroidogenic limiting factors in adrenocortical cells isolated from halothane nn pigs

Previous studies demonstrated significantly lower plasma cortisol level in homozygous halothane-positive (Hal nn) pigs, as compared with homozygous halothane-negative (Hal NN) pigs. To determine whether such difference is attributed to the fundamental alterations in adrenocortical function, F1 offsprings from Pietrain (Hal nn)xErhualian (Hal NN) were intercrossed to produce F2 sibling pigs with segregated genotypes. Adrenocortical cells were isolated from the Hal nn and Hal NN F2 pigs, respectively, and cultured with or without ACTH challenge. Cortisol levels in culture medium, as well as the content of MC2R, cAMP, CREB, phosphorylated CREB (pCREB), StAR and P450scc in adrenocortical cell lysates, were determined. Cortisol, cAMP, StAR and P450scc levels were significantly lower in Hal nn adrenocortical cells under basal condition without ACTH challenge. ACTH significantly increased cortisol level in the medium and the protein content of MC2R, StAR, P450scc in adrenocortical cell lysates, regardless of genotypes. Total CREB protein content was not different between genotypes and treatments, whereas pCREB content exhibited significant effects of genotype and treatment, being higher in Hal NN than in Hal nn under basal condition and in response to ACTH challenge. These results indicate that the compromised cAMP/PKA/pCREB signaling pathway of ACTH and diminished expression of limiting factors in adrenocortical steroidogenesis (StAR and P450scc) may contribute to the significantly lower plasma cortisol levels in Hal nn pigs.     

北京地区种猪氟烷基因分布的研究

[目的]了解北京地区种猪群氟烷基因（Haln）的分布状况。[方法]采用PCR-RFLP对北京地区公猪站、种猪场共计609头种猪进行氟烷基因检测。[结果]公猪站大白猪、长白猪、杜洛克、皮特兰的Haln基因频率分别为0、17.11%、5.56%和18.75%;种猪场大白猪、长白猪、杜洛克的Haln基因频率分别为4.52%、11.68%和23.33%。[结论]该研究结果为合理利用氟烷基因提供依据。     

SNaPshot based genotyping of the RYR1 mutation in Portuguese breeds of pigs

The porcine stress syndrome or malignant hyperthermia is an inherited autosomic recessive disease, which results in neuromuscular disorders leading to death in homozygous individuals and is associated with deterioration of meat quality. The defect in susceptible animals results from modifications in the calcium release channel or Ryanodine Receptor (RYR1), with a mutation leading to a C to T transition in nucleotide 1843 of the gene. The objective of this work was to develop a method based on analysis of SNPs to detect the mutation described in the RYR1 locus in pigs, and study polymorphisms of the gene in four exotic (Large White, Landrace, Duroc and Pietrain) and three native (Bísaro, Alentejano and Malhado de Alcobaça) breeds of pigs in Portugal. The method was successful in identifying the mutation by analysis of SNPs, and results indicate a high incidence of the mutant allele in Pietrain (0.75) and, to a lesser degree, in Malhado de Alcobaça (0.34) and Landrace (0.28); frequencies in Alentejano, Bísaro and Large White ranged between 0.04 and 0.09. These results suggest the need to establish breeding programs aimed at eliminating the susceptibility allele from those populations.     

大白猪育种核心群氟烷基因PCR—RFLP检测及其净化

采用PCR—RFLP技术,对正邦集团大白猪原始基础群及其育种核心群0、1世代共538头个体,以及红星衣场大白猪原始基础群和育种核心群0世代共249头个体进行氟烷基因（Hal）基因型检测,并对阳性个体予以清除使其净化。基因继代选择结果显示,正邦原始基础群及核心群0、1世代群体Hal^n基因频率分别为9．48％、2．22％、0;红星原始基础群及核心群0世代群体Hal^n基因频率分别为1．08％、0,呈现世代递减并实现净化,进而培育出大白猪抗应激品系。研究表明,PCR—RFLP技术可准确诊断猪氟烷基因,在种猪选育过程中及时淘汰携带氟烷基因的个体,提高猪种质量。