母猪配种实施方法

1 母猪发情征状 发情母猪表现兴奋不安，有时哼叫，食欲减退。非发情母猪食后上午均喜欢趴卧睡觉，而发情的母猪却常站立于圈门或爬跨其他母猪。公猪与母猪并圈。发情母猪会主动接近公猪。鉴定人员慢慢靠近疑似发情母猪臀后认真观察阴门，白色猪表现潮红、水肿有的有黏液流出。黑色猪或其他有色猪只能看见水肿及黏液变化。     

快速鉴定母猪发情技术“三法”

发情鉴定的目的是及时发现发情母猪，准确判断母猪的发情阶段，正确掌握配种或人工授精的最佳时间，防止误配漏配，提高受胎率。母猪的发情鉴定技术一般采用以下几种方法：     

母猪的仿生法发情鉴定

母猪的仿生法发情鉴定何英俊（浙江省金华农业学校）母猪的发情鉴定是繁殖工作中的重要技术环节之一。通过发情鉴定，可正确确定配种适期，提高受胎率。目前猪的发情鉴定大多采用外部观察，结合压背试验、公猪试情等方法。外部观察虽简单，但对一些隐性发情及发情不明显的...     

试谈母猪不发情和易返情的对策

在猪的繁殖工作中，发情鉴定是一个重要的技术环节。母猪性成熟以后，卵巢中规律性地进行着卵泡成熟和排卵过程，通过发情鉴定，可以判断母猪发情是否正常，以便发现问题，进行及时解决；也可以判断母猪发情阶段，确定配种适期，提高受胎率。本文初步探讨了母猪不发情和易返情的对策。     

浅谈断奶母猪不发情原因及防治

正常情况下，母猪在仔猪断奶后7～10天就会发情。但生产中常常可以看到母猪断奶后20天内不能正常自然发情．甚至有的超过30天还未出现发情．或母猪断奶后乏情的发生。母猪发情间隔时间长或不发情是目前规模化、标准化养瘦肉型品种母猪及其杂交母猪中普遍存在的一个繁殖障碍问题，     

后备母猪乏情的原因及对策

后备母猪达到一定年龄和一定体重后不发情、发情症状不明显或安静发情等都统称为后备母猪乏情。一般来说，正常情况下外来品种及其杂交的后备母猪5-6月龄就进入初情期，如果超过了7月龄或体重达到120kg后，还没有出现过一次发情症状，就可视为乏情。     

外二元杂交母猪难发情的处理建议

在养猪生产管理的各个环节中，最重要的技术之一是准确地和有效地判定母猪的正常发情．那我们就可以得到母猪的高怀孕率，将来会得到的生产效益和经济效益就越高。所以促使母猪正常发情是提高母猪繁殖率和养殖经济效益的重要措施，掌握好母猪难发情的处理措施，具有很高的实用价值．     

几种母畜异常发情的防治

在畜牧业生产中养牛、养猪、养羊是畜牧业发展的一个重要的组成部分，畜牧业要发展母畜生产是关键。母牛、母猪、母羊如果受生理、营养、疾病、年龄、应激等因素影响，往往会导致异常发情。异常发情将会延误配种，增加了饲料消耗及其它饲养费用，给养殖业造成严重的经济损失。本文对母牛、母猪、母羊的常见的异常发情进行了综述，并提出了针对性的防治措施，为母牛、母猪、母羊生产提供一定的参考。     

正常发情与异常发情对大白猪繁殖性能的影响

本试验旨在研究大白母猪配种前的状态对其繁殖性能的影响。试验按配种前的状态分为正常发情配种母猪组（仔猪断奶7 d内发情配种）与异常发情配种母猪组（仔猪断奶7 d后发情配种、流产后再发情配种、妊娠后复发情配种）,比较2组母猪的繁殖记录,分析正常发情与异常发情对大白猪繁殖性能的影响。试验结果表明,配种前大白母猪的发情状态对窝总产仔数、产活仔数、初生窝重无显著影响（P>0.05）;正常发情配种母猪产木乃伊胎数高于异常发情配种母猪,差异显著（P<0.05）;异常发情配种母猪产死胎数有增多的趋势,差异不显著（P>0.05）。本试验通过对正常发情和异常发情母猪繁殖性能的比较研究,初步了解了母猪配种前不同发情状态下的繁殖性能,为大白猪的繁殖管理、特别是配种前发情状态管理提供参考。     

提高母猪产仔三措施

要想提高母猪的饲养效益,提高母猪的产仔率是关键,而提高母猪的产仔率,关键在于配种。1掌握好母猪适宜的配种时间。一般情况下,母猪发情的持续时间为2～3天,但母猪排卵时间常常在发情后期,也就是发情后的2～3天。所以,母猪发情后的适宜配种时间是发情后的2～3天。     

Evaluation of methods of providing supplemental heat to newborn pigs during and after farrowing.

Two experiments were conducted to evaluate systems of providing supplemental heat to newborn pigs during and after farrowing. In Exp. 1, 35 sows were randomly allotted to farrowing crates with two supplemental heat treatments: 1) two lateral 250-watt heat lamps; and 2) two lateral heat lamps, plus a 250-watt heat lamp behind the sow during farrowing. In Exp. 2, 72 sows were randomly assigned to farrowing crates with four supplemental heat treatments: 1) one lateral 250-watt heater; 2) one lateral heater plus a 250-watt heater behind the sow during farrowing; 3) a hover with 100-watt light bulb; and 4) a hover with light bulb plus heater behind the sow during farrowing. The average farrowing house temperature was 18.9 degrees C in Exp. 1 and 21.6 degrees C in Exp. 2. Results showed no significant treatment effects on preweaning pig survival or growth rates in either experiment. Thus, providing a heat lamp at the rear of the sow during parturition was not beneficial and would increase operating costs. Hovers have a higher initial cost than conventional heat lamps or heaters, but they would have a much lower operating cost. Hovers may offer swine producers a way of reducing energy costs without affecting preweaning pig survival and performance.     

Sow line differences in heat stress tolerance expressed in reproductive performance traits

The objectives of this study were 1) to investigate if there were differences in the relation between temperature and reproductive performance traits in 2 different sow lines, a Yorkshire line producing mainly in temperate climates and a Large White line producing mainly in warm climates, and 2) to determine the upper critical temperature (UCT) for the reproductive performance of these 2 lines. Sows are exposed to heat stress when temperature exceeds the UCT of the thermo-neutral zone. Data included 32,631 observations on reproductive performance from 11,935 sows on 20 farms in Spain, collected from 2003 to 2005. Sows belonged to 2 different purebred sow lines, named D (Yorkshire sow line, producing mainly in temperate climates) and I (Large White sow line, producing mainly in warm climates). Only first insemination records per parity were used and were combined with the maximum outside temperature at day of insemination. Upper critical temperatures were studied for 3 reproduction traits: farrowing rate (0 or 1), litter size (range from 1 to 25), and total number of piglets born per first insemination (combination of farrowing rate and litter size, range from 0 to 25). Data were corrected for fixed effects, which included parity, service sire, and an interaction between farm and year. Corrected data were used as observations in the models to study the effect of outside temperature on reproductive performance. Two models were compared for goodness of fit: a linear regression model and a plateau-linear model with the plateau representing the thermo-neutral zone and a linear decrease above that zone. Farrowing rate of I-line sows was not affected by temperature. For litter size and total number born per first insemination of I-line sows no UCT could be estimated. These traits were linearly affected by temperature. For all 3 reproduction traits of the D-line the best model was the plateau-linear model; the UCT for the D-line sows was estimated to be 19.2 degrees C for farrowing rate, 21.7 degrees C for litter size, and 19.6 degrees C for total number born per first insemination. The decrease in reproductive performance of I-line sows with increasing outside temperature was less than in D-line sows. From this study it can be concluded that there are differences in heat stress tolerance between sow lines as measured by the differences in reproductive performance. These differences are an indication of genetic differences in heat stress tolerance in sow lines.     

Photoperiod and heat stress influence on lactating sow performance and photoperiod effects on nursery pig performance

Three experiments were conducted to evaluate sow and piglet productivity under extended photoperiod. In Exp. 1, 98 crossbred, lactating sows were housed in one of four treatments: thermoneutral air temperature (23.6 degrees C) in either (h of light:dark) 1:23 or 16:8 photoperiods, or heat stress (30.4 degrees C) in either 1:23 or 16:8 photoperiods. Heat stress reduced (P less than .05) sow feed intake, piglet mortality and piglet weaning weight and increased (P less than .01) sow lactation weight loss. Number of pigs weaned per litter was increased (P less than .01) when sows were heat-stressed. Extended photoperiod reduced (P greater than .05) time for sows to rebreed postweaning by .4 d. The interaction between air temperature and photoperiod was significant only for sow lactation weight loss. Heat stress increased sow lactation weight loss, but this effect was more severe in the 1:23 than in the 16:8 photoperiod. Experiments 2 and 3 examined the effects of 1:23 or 16:8 photoperiods on nursery pig performance when pigs were weaned from sows experiencing 1:23 (Exp. 3) or 16:8 (Exp. 2) photoperiods. In both nursery studies, photoperiod did not influence (P greater than .10) postweaning pig mortality, feed intake, weight gain or gain:feed ratio. In conclusion, extended photoperiod reduced days to return to estrus and reduced sow lactation weight loss, especially during heat stress. No benefits in preweaning or postweaning piglet weight or survival were observed by use of extended photoperiod.     

Management of lactating sows during heat stress: effects of water drip, snout coolers, floor type and a high energy-density diet

Two experiments using 120 sows were conducted to determine the effects during heat stress of two floor types, snout coolers or a water drip system, and a high energy-density diet. During both studies, air temperature was maintained at or above 29 degrees C. Floor types included partially slotted concrete and plastic-coated, expanded metal. In Exp. 1, in addition to floor-type treatments, snout coolers were on or off and the water drip was on for 3 min each 10 min or off. Snout coolers increased (P less than .05) sow feed intake and decreased (P less than .05) sow lactation weight loss. Water drip increased (P less than .002) sow feed intake and reduced lactation weight loss. The drip X floor-type interaction was significant for most measures of piglet performance. Drip was beneficial for piglet weights when piglets were on plastic, whereas drip was detrimental to piglet performance while they were housed on concrete. In Exp. 2, two floor types, drip or no-drip and a high energy-density diet or control diet were examined during heat stress. The high energy-density diet reduced (P less than .01) sow feed intake but provided no measurable increase in piglet performance during heat stress. We conclude that water drip is an effective cooling technique for heat-stressed sows, especially when floors are plastic. Snout coolers, partial concrete slots and high energy-density diets provided only minor benefits to heat-stressed sows and were not of benefit to piglets nursing heat-stressed sows.     

Effects of heat stress on piglet production/performance parameters

Heat stress is problematic for pigs raised in tropical environments. The animal is large and has proportionally high body heat, and subcutaneous fat thickness reduces the animal’s ability to thermoregulate. It is not clear how stress affects pig litter size. For this reason, we performed a meta-analysis of the effect of heat stress on pig litter size. We reviewed behavioral, endocrine, and cellular data and the signaling pathways involved in heat stress. We found that heat stress did not affect litter size or the body weight of offspring. However, heat stress was found to decrease litter body weight gain due to reductions in sow milk production. For this reason, artificial feeding of piglets may be appropriate.     

膨化菜籽对哺乳母猪生产性能的影响

为研究夏季热应激情况下使用全脂膨化菜籽配制哺乳母猪饲粮对其生产性能的影响,选择妊娠107 d不同胎次的长大母猪30头,采用随机区组设计分为3组,每组10头母猪,分别接受3种饲粮处理：即试验1组（5.63%膨化菜籽）、试验2组（9%膨化菜籽）、对照组（2%猪油＋5%膨化大豆）。结果表明,母猪哺乳期第18至第22天日采食量,试验1组和试验2组分别比对照组提高0.90和0.38 kg;哺乳期第18至第22天日采食量峰值,试验1组和试验2组分别比对照组提高0.64和0.23 kg;日采食量达到峰值后下降速度,试验1组和试验2组分别比对照组低50%和42.5%。试验1组、试验2组和对照组母猪失重率均较小,分别为3.10%、5.90%、4.63%;母猪断奶后1周内全部发情。哺乳仔猪窝增重,试验1组和试验2组分别比对照组提高0.65、0.75 kg。哺乳仔猪18日龄以前没有出现腹泻,19～22日龄出现轻微腹泻,且腹泻率很低。乳品质,试验1组和试验2组优于对照组;血液生理生化指标,3组均在正常范围内。说明使用全脂膨化菜籽配制的哺乳母猪饲粮适口性好,能显著增加热应激情况下哺乳母猪的采食量,改善乳品质,提高其生产性能,效果优于添加猪油＋膨化大豆的饲粮。     

Exploratory spatial analysis of Aujeszky's disease during four phases of the eradication programme in Catalonia, Spain (2003-2007)

An exploratory spatial analysis of Aujeszkys disease virus infection from 2003 to 2007 was conducted in Catalonia (north eastern Spain), the largest pig-producing region in the country. The analysis was divided into four periods in relation to the different eradication phases of the programme established in the region. Different purely spatial analyses, based on the Bernoulli model, were run with SaTScan v6.1 in each period. Clusters of positive sow farms (farrow to weaning and farrow to finish) and/or fattening farms were identified in the four study periods in the western part of the region, in the three first periods in the central part and in the last three periods in the north eastern part of the region. The prevalence ratio values of these clusters increased throughout the study period due to the fact that the risk of disease decreased faster outside the clusters than inside the clusters. In order to study the evolution of the disease, we explored for areas where more negative sow farms became infected and areas where more sow farms eliminated the infection. These analyses demonstrated areas with significantly higher proportions of sow farms that became negative, which indicates that the eradication of the disease had a spatial component. Clusters of negative sow farms that were infected again (reinfections) were also detected in the four study periods. The relative risk values of these clusters were much higher compared to the other cluster analyses. There was a geographical association between the clusters of positive sow farms, positive fattening farms and re-infected sow farms. This association could be attributable to the local spread of Aujeszkys disease virus. Pig farm density could be a factor influencing the local spread of infection and was therefore evaluated for clusters of re-infected sow farms and clusters of sow farms that eliminated the infection. The mean density of pig farms was 0.40 farms/km(2) (median of 0.28 and standard deviation of 0.33) in clusters of sow farms that became negative and 1.51 (median of 0.70 and standard deviation of 1.61) in clusters where more sow farms became positive (p-value<0.05).     

Economic analysis of outbreaks of porcine reproductive and respiratory syndrome virus in nine sow herds

The economic losses due to porcine reproductive and respiratory syndrome virus (PRRSv) outbreaks are reported in the literature to be substantially high, but recent figures are not available. The aim of this study was to quantify the economic effects of epidemic PRRSv outbreaks in Dutch sow herds. Nine sow herds were selected based on a confirmed PRRSv outbreak within those populations. The economic impact during the first 18 weeks after the outbreak was estimated by comparing the overall costs between pre- and postoutbreak periods, using different factors (production data, medication, diagnostics, labour, etc.). An outbreak of PRRSv resulted in a reduced number of sold pigs per sow of 1.7. The economic loss varied between €59 and €379 for one sow per 18-week period outbreak. The mean loss per sow per outbreak was €126. The costs after the outbreak varied significantly from €3 to 160 per sow, due to the different methods used by farmers to tackle PRRSv outbreaks. The calculated costs in this study correlate with the costs of the initial outbreak in The Netherlands of 98 per sow.     

Bioeconomic evaluation of sow longevity and profitability

Sow production indicators, including litter size, litter weight, and the length of time that sows remained in the herd (sow longevity), were used to characterize sow performance and profitability. Sow longevity and production records from 148,568 sows in 32 commercial herds from Central Illinois from January 1995 to May 2001 were analyzed using survival and repeatability models, respectively. The factors studied included sow genetics (32 genetic lines), with eight major lines present in multiple herds, and the combination of herd and year of entry in the herd. The largest difference in longevity between the major genetic lines was approximately one parity. There were differences (P < 0.05) in the instantaneous sow removal rate or hazard from the major lines. These differences constitute evidence that sow longevity could be improved by using replacements from specific genetic lines. The net present value per sow (present value of future cash flows and the present value of the sow) was used to evaluate the effect of sow longevity and production traits on economic returns. Assuming a zero discount rate per parity, genetic lines with longer herd life resulted in greater profit than genetic lines with shorter herd life. This difference was reduced with increasing discount rates and was reversed with high discount rates and low net income per litter. These results suggest that the magnitude of the economic improvement attained through the use of sow genetic lines with longer longevity depends on the economic context under which the evaluation is made.     

Timing and temperature thresholds of heat stress effects on fertility performance of different parity sows in Spanish herds

High temperature is an environmental factor that impairs sow fertility. In this study, we identified the critical weeks for heat stress effects on aspects of fertility performance, namely weaning-to-first-service interval (WSI) and farrowing rate (FR). We also examined the threshold temperatures above which the fertility performance deteriorated and whether there were any differences between parities regarding heat stress effects or thresholds. Performance data of sows in 142 herds from 2011 to 2016 were matched to appropriate weekly averaged daily maximum temperatures (T_max) from weather stations close to the herds. Two types of ratios (i.e., ratio for WSI and odds ratio for FR) were used to identify the critical weeks for heat stress by comparing the respective measures for two sow groups based on T_max in different weeks around weaning or service events. The ratios for WSI were calculated between groups of sows exposed to T_max ≥ 27 °C or <27 °C in each week before weaning, with the T_max cutoff value based on a recent review study. Similarly, the odds ratios for FR for the two groups were calculated in weeks around service. The weeks with the largest differences in the fertility measures between the two T_max groups (i.e., the highest ratio for WSI and the lowest odds ratio for FR) were considered to be the critical weeks for heat stress. Also, piecewise models with different breakpoints were constructed to identify the threshold T_max in the critical week. The breakpoint in the best-fit model was considered to be the threshold T_max. The highest ratios for WSI were obtained at 1 to 3 wk before weaning in parity 1 and 2 or higher sow groups. The threshold T_max leading to prolonged WSI was 17 °C for parity 1 sows and 25 °C for parity 2 or higher sows. Increasing T_max by 10 °C above these thresholds increased WSI by 0.65, and 0.33 to 0.35 d, respectively (P < 0.01). For FR, the lowest odds ratios were obtained at 2 to 3 wk before service in parity 0, 1, and 2 or higher sow groups. The threshold T_max leading to reductions in FR was 20, 21, and 24 to 25 °C for parity 0, 1, and 2 or higher sow groups, respectively. Increasing T_max by 10 °C above these thresholds decreased FR by 3.0%, 4.3%, and 1.9% to 2.8%, respectively (P < 0.01). These results indicate that the critical weeks for heat stress were 2 to 3 wk before service for FR and 1 to 3 wk before weaning for WSI. The decreases in fertility performance in parity 0 to 1 sows started at temperatures 3 to 8 °C lower than in parity 2 or higher sows.