妊娠－泌乳母猪钙代谢及调控机理研究进展

母猪的生产性能受很多因素的影响，其中日粮矿物质水平是其主要影响因素之一。钙在调控母猪的生产性能方面发挥着重要的作用。机体钙吸收的方式有3种，即主动转运、被动转运和囊泡运输，激素或者其他影响钙吸收的因素大多是通过调控钙吸收方式进而影响日粮钙的利用率。母猪对日粮钙的利用率直接影响其生产性能的发挥，一方面，适当的日粮钙水平可以促进母猪发挥最大的生产潜能，提高养殖效益；另一方面，当日粮钙水平不足或者钙利用率低时，首先，母猪的生产性能潜力不能充分发挥，如产仔数或活仔数低，仔猪的生长速度慢。其次，母猪由于钙利用不足而导致骨骼疾病的发生，尤其是妊娠后期和哺乳期的母猪，最终使其淘汰率居高不下，这一系列的因素最终导致养殖业的生产效益大幅度降低。近年来，国内外学者针对影响母猪对日粮钙利用率的因素进行了大量的研究，并取得了很大的进展，例如，钙的饲喂时间、日粮钙磷比、维生素、激素和消化道pH均影响母猪对日粮钙的吸收利用。因此，研究母猪钙吸收特征及其影响因素对提高母猪生产性能具有重要的实践意义。作者简述了机体钙吸收的作用机制，同时介绍了影响母猪钙吸收的主要因素，旨在为母猪日粮钙的饲喂提供理论依据。     

提高母猪生产性能技术措施

母猪生产性能主要体现在其繁殖性能上,在研究中母猪的繁殖性能受到很多因素的影响,包括饲养管理、疾病控制、环境、遗传等因素,所以要考虑各个因素对母猪的影响情况,结合生产者生产实际,抓住母猪生产各个环节,才能提高母猪生产性能。该文分析母猪生产相关因素,提出广泛适合我国各地生产措施。     

营养素及添加剂改善哺乳母猪泌乳力、生产性能和血液参数的研究进展

在母猪妊娠期和泌乳期日粮中添加不同水平的营养素或添加剂可改善哺乳母猪的泌乳力、生产性能和某些血液参数。文章就添加蛋白质、氨基酸、油脂、纤维、微量元素、维生素及添加剂对哺乳母猪的影响展开分析。     

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。     

母猪情期启动营养调控分子机制的探讨

养猪生产中后备母猪年更新率高达40％～50％,哺乳母猪断奶后情期启动失败被淘汰比例占30％～40％,50％的母猪终身仅提供30～40头断奶仔猪就被淘汰,给养猪生产带来巨大经济损失.大量研究表明,下丘脑Kisspeptin信号系统在调控雌性动物情期启动和卵泡发育方面发挥重要作用.本课题组前期研究证实,猪的情期启动只有在营养充足、机体处于合成代谢时才能发生和维持.营养是推动后备母猪由生长向繁殖转换,或断奶母猪由泌乳向繁殖转换的物质基础.本文提出了营养调控母猪情期启动的几种理论假设,综述了能量、蛋白质(氨基酸)、维生素D3和部分矿物元素对机体代谢和下丘脑Kisspeptin信号的影响及其在调控母猪情期启动方面的分子机制.     

Comparative effects of sodium butyrate and flavors on feed intake of lactating sows and growth performance of piglets

We examined the effects of sodium butyrate and flavors on feed intake of lactating sows and growth performance of piglets. A total of 52 primiparous sows (Large White) were randomly divided into four treatments (n = 13) and received 6 g/kg sodium butyrate (SB), fruit‐milk (FM) flavor and fruit‐milk‐anise (FMA) flavor with pair feeding to the mothers receiving the control diet. The feeding trial lasted for 29 days, including 21 days of nursing and 8 days of post‐weaning period, respectively. The nursing and weaning piglets received creep diets with the same flavor or SB supplement as their mother. The results showed that FMA flavor increased average daily feed intake (ADFI) of lactating sows (P < 0.01), as well as improved litter weight gain (P = 0.05) and ADFI (P < 0.01) of nursing pigs among treatments. Indeed, greater ADFI and average daily gain of weaning piglets for the initial 8 days after weaning was observed in the FMA group compared with those in the control group (P < 0.01). These findings indicated that adding FMA flavor was superior to SB for increasing feed intake of lactating sows and improving growth performance of piglets.     

Effects of cooled floor pads combined with chilled drinking water on behavior and performance of lactating sows under heat stress

This study was conducted to evaluate whether cooled floor pads combined with chilled drinking water could alleviate negative impacts of heat stress on lactating sows. Thirty sows (Landrace × Yorkshire, Parity = 1 to 6) were housed in individual farrowing stalls in two rooms with temperatures being controlled at 29.4°C (0700–1900 hours) and 23.9°C (1900–0700 hours). Sows in one room (Cool), but not in the other room (Control) were provided cooled floor pads (21–22°C) and chilled drinking water (13–15°C). Behavior of sows (15 sows/treatment) was video recorded during farrowing, and days 1, 3, 7, 14, and 21 after farrowing. Videos were viewed continuously to register the birth time of each piglet, from which total farrowing duration and birth intervals were calculated. The number of drinking bouts and the duration of each drinking bout were registered for each sow through viewing videos continuously for 2 h (1530–1730 hours) each video-recording day. Postures (lying laterally, lying ventrally, sitting, and standing) were recorded by scanning video recordings at 5-min intervals for 24 h each video-recording day, and time budget for each posture was calculated. Rectal temperature and respiration rate were measured for all sows the day before and after farrowing, and then once weekly. Sow and litter performance was recorded. Data were analyzed using the Glimmix procedure of SAS. The cooling treatment did not affect sow behavior or litter performance. Sows in the Cool room had lower rectal temperature (P = 0.03) and lower respiration rate (P < 0.001), consumed more feed (P = 0.03), tended to have reduced weight loss (P = 0.07), and backfat loss (P = 0.07) during lactation than sows in the Control room. As lactation progressed, sows increased drinking frequency (P < 0.001) and time spent lying ventrally (P < 0.0001), standing (P < 0.001), and sitting (P < 0.0001), and decreased time spent lying laterally (P < 0.0001) in both Cool and Control rooms. While cooled floor pads combined with chilled drinking water did not affect sow behavior, they did alleviate heat stress partially, as indicated by decreased rectal temperature, respiration rate, weight, and backfat loss, and increased feed intake in lactating sows.     

Behavioral and stress responses to feeding time in pregnant sows under limit-fed regime

We investigated the effect of feeding time on behavior and stress responses in pregnant sows under isocaloric conditions. Twenty-four sows were balanced for parity and randomly assigned to 1 of 3 feeding times. Corn–soybean meal-based diet was fed once at: 0730 (Control, T1), 1130 (T2), and 1530 hours (T3). On average, sows received 7,062 kcal ME/d from 2.20 kg of diet formulated to contain SID Lys/ME of 1.71 g/Mcal. The study was conducted for 28 d (21 d acclimation to the feeding regime and 7 d data collection). Saliva samples were collected every 2 hr for 12 hr in stalls on day 52 of pregnancy. Behavior data were collected 24 hr for 7 d from day 53 of gestating by affixing a remote insights ear tag to each sow. Each sow had 120,960 data points categorized into: “Active,” “Feed,” or “Dormant”. Due to housing constraint, all sows were housed in individual stalls in the same barn presenting a potential limitation of the study. Data were analyzed using PROC MIXED and GLIMMIX procedures of SAS 9.4 for cortisol and behavior data, respectively. Sow was the experimental unit. The area under the curve (AUC) is quantitative evaluation of response as threshold varies over all possible values. A 12-hr cortisol total AUC for sows fed once daily at 1130 hours was reduced relative to sow group fed at 1530 hours (P = 0.046) but similar compared with the control sows (P = 0. 323). The control sows (0730 hours) had reduced total (P < 0.001) and feeding (P = 0.001) activity AUCs relative to sows on 1130 hours but did not differ compared with sows on 1530 hours feeding schedules (P > 0.100). Sows on 1130 hours feeding schedule had greater feed anticipatory activity, 24-hr total activity count, total (P < 0.001) and feeding (P < 0.001) activity AUC compared with sows fed daily at 1530 hours. In conclusion, feeding pregnant sows earlier in the morning (0730 hours) appears to minimize sows’ behavior but similar cortisol response. Sows on 1130 hours feeding schedule had greater activities but reduced cortisol concentration, suggesting that elevated sow activity might not necessarily indicate activation of hypothalamic–pituitary–adrenal axis.     

定时输精对经产母猪繁殖性能及生殖激素的影响

试验旨在建立高效的经产母猪定时输精（timed artificial insemination,TAI）技术,研究了定时输精对经产母猪繁殖性能、断奶-分娩间隔、不同胎次母猪产仔性能及断奶后7 d内血清生殖激素水平的影响。选取309头2~8胎次二元（长×大）经产母猪,随机分为对照组和试验组,对照组母猪进行常规人工授精（artificial insemination,AI）,试验组母猪进行断奶后24 h注射PMSG 1 000 IU,间隔72 h注射GnRH 100 μg,在注射GnRH后24和40 h各输精1次的定时输精技术。通过统计两组母猪的断奶1周内发情率、受胎率、分娩率、窝均产仔数等,判断定时输精对经产母猪繁殖性能的影响;通过对断奶时间和分娩时间的统计,检测定时输精对经产母猪断奶-分娩间隔的影响;用放射免疫（RIA）方法检测2~4胎次母猪断奶1周内血清E₂、LH、FSH和P₄的含量,研究定时输精对母猪生殖激素的影响。结果显示,试验组母猪发情率显著高于对照组（P<0.05）,但两组间受胎率、分娩率差异不显著（P>0.05）,窝均产仔数、窝均合格仔数和繁殖效率有增加的趋势,但差异不显著（P>0.05）;定时输精显著缩短了母猪的断奶-分娩间隔（P<0.05）。在胎次方面,3~4胎母猪使用定时输精的效果较好,其发情率、受胎率和分娩率均显著高于对照组（P<0.05）。在生殖激素方面,试验组E₂水平在注射PMSG后迅速上升,且在定时输精处理后66~96 h内持续高于对照组（P<0.05）,试验组P₄水平在断奶后至配种前显著低于对照组（P<0.05）,但配种后快速升高,并高于对照组;LH和FSH的含量在两组间无显著差异。综上,定时输精可有效提高经产母猪的断奶发情率,并减少其非生产天数,可显著提高3~4胎母猪的繁殖性能。     

氯前列醇钠与卡贝缩宫素对荣昌猪和涪陵黑猪母猪分娩时间的影响

氯前列醇钠作为人工合成的前列腺素类似物被广泛的应用于诱导各种母畜的分娩。卡贝缩宫素作为一种具有长效特性的新型催产素类样分子,有望在母猪分娩过程中替代缩宫素起到收缩子宫启动分娩的作用。试验一主要对氯前列醇钠注射部位和剂量进行研究,将母猪随机分为自然分娩组(n=74)、2 mL肌肉注射组(n=52)、2 mL后海穴注射组(n=63)和1 mL后海穴注射组(n=57)。研究结果表明,2 mL后海穴注射组的母猪分娩时间上表现更为集中,产仔持续时间最短(228 min),白天分娩比例最高(90.48%)。说明通过调整母猪注射氯前列醇钠时间、剂量以及部位等因素能够一定程度的缩短母猪产仔时间,提高母猪白天分娩率。试验二主要对卡贝缩宫素(CBT)与氯前列醇钠的联合应用进行研究,试验将母猪随机分为自然分娩组(n=81)、氯前列醇钠注射组(n=70),CBT注射组(n=67),氯前列醇钠+CBT注射组(n=64)。研究结果表明,氯前列醇钠与卡贝缩宫素联合应用能够缩短母猪产仔持续时间(205 min),并且大幅提高母猪在白天工作时间分娩比例(95.31%)。