从饲喂策略考虑提高母猪泌乳期采食量

母猪泌乳期高自由采食量(VFI)是其繁殖性能正常发挥的保证。为了提高母猪泌乳期VFI,文中分析了母体因素如品种、基因、带仔数、体况等对VFI的影响,提出着重从全繁殖周期饲喂策略考虑,以提高母猪泌乳期VFI。     

Mineral nutrition of the sow: a review

The sow varies greatly in her mineral requirements, which largely reflects the nutritional demands during different phases of her reproductive cycle. Minerals are required for conceptus product formation, mammary secretions, and growth and maintenance. Although the sow's mineral requirements are highest during late gestation and lactation, those that are supplied from the diet and tissue reserves both contribute in meeting these nutritional needs. The sow is fairly resilient to borderline mineral insults, but longevity in the herd may be compromised under these conditions. Specific mineral deficiencies vary, but the reproducing sow will deplete the pool of tissue minerals before litter size, congenital abnormalities of developing fetuses or milk mineral composition are affected. Inadequate mineral supplies may prolong the duration of parturition, increase the number of stillbirths and result in a higher occurrence of skeletal problems. Tissue mineral reserves can be increased in various tissues with higher dietary fortification, but subsequent mineral availability from various pools differ. Because feed intake during lactation is low, daily mineral intake during lactation often is below NRC (1988) requirements.     

Improving sow productivity through management during gestation, lactation and after weaning

Number of pigs produced per sow per year is dependent upon the number of pigs born live, the number that survive to weaning and the interval between consecutive farrowings for the sow. Feeding and management of the sow during late gestation affects birth weight and amount of energy stored as glycogen and lipid in the piglet. Piglets that are heavier and that have more energy stores have a higher survival rate. Adding fat to the sow's diet during the last month of gestation or altering the sow's metabolism to direct more nutrients to the fetus are methods for increasing piglet birthweight and energy stores. Feeding the sow properly during lactation is important for maximum yield of milk and milk energy, which affects survival of pigs to weaning, and for rebreeding performance of the sow after weaning. Energy intake during lactation can be increased by adding fat to diets, and this is beneficial in situations where feed intake is insufficient to meet the sow's requirements. For example, fat supplementation during lactation is beneficial for primiparous sows and for sows lactating during hot weather. The minimum practical lactation length is about 2 wk for normal rebreeding performance of the sow. Split weaning or separation of the litter from the sow for 6 to 12 h/d will shorten the rebreeding interval or induce estrus during lactation. Administration of pregnant mare's serum gonadotropin, with or without human chorionic gonadotropin, will induce estrus during lactation, and the response is better after the second week of lactation. Similar treatments at weaning will shorten the rebreeding interval.(ABSTRACT TRUNCATED AT 250 WORDS)     

National Pork Producers Council Maternal Line National Genetic Evaluation Program: a comparison of sow longevity and trait associations with sow longevity

Data from the National Pork Producers Council Maternal Line National Genetic Evaluation Program were used to compare longevity of sows from 6 commercial genetic lines and to estimate the phenotypic associations of sow longevity with gilt backfat thickness, ADG, age at first farrowing, litter size at first farrowing, litter weight at first farrowing, average feed intake during lactation, and average backfat loss during lactation. The lines evaluated were American Diamond Genetics, Danbred North America, Dekalb-Monsanto DK44, Dekalb-Monsanto GPK347, Newsham Hybrids, and National Swine Registry. The data set contained information from 3,251 gilts, of which 17% had censored longevity records (sows lived longer than 6 parities). The line comparison was carried out by analyzing all lines simultaneously. Because the survival distribution functions differed among genetic lines, later analyses were carried out separately for each genetic line. All analyses were based on the non-parametric proportional hazard (Cox model). Dekalb-Monsanto GPK347 sows had a lower risk of being culled than sows from the other lines. Moreover, the shape of the survival distribution function of the Delkab-Monsanto GPK347 line was different from the other 5 lines. The Dekalb-Monsanto 347 line had lower culling rates because they had lower gilt reproductive failure before the first parity than gilts from the other lines. Within line, sows with lower feed intake and greater backfat loss during lactation had a shorter productive lifetime. Thus, producers should implement management practices having positive effects on sow lactation feed intake. Additionally, the swine genetics industry is challenged to simultaneously improve efficiency of gain of their terminal market pigs and to obtain high feed intake during lactation of their maternal lines for future improvement of sow longevity. Recording sow feed intake and backfat loss during lactation in nucleus and multiplication breeding herds should be considered. Between-line differences in this study indicate that it is possible to select for sow longevity, but more research is needed to determine the most efficient selection methods to improve sow longevity.     

A Delphi exercise used to identify potential causes of variation in litter size of Ontario swine

Forty-eight people, considered to the swine experts, were asked to collaborate in a Delphi exercise to identify the factors which they believed affect litter size in Ontario swine. The panel included 16 animal scientists, 16 pork producers, and 16 veterinarians in swine practice. The ten factors with the highest ratings were parity of the sow, mycotoxins in the feed, infections with porcine parvovirus or Leptospira spp., breeding gilts on their second versus first observed estrus, the timing of breeding with respect to the onset of estrus, purebred versus crossbred sows, boar overuse (bred by a boar that was mated more than six times per week), pen versus hand mating, age of gilt when first bred, and body condition of the sow at the time of conception. The experts did not agree about the effect on litter size of the sow's previous lactation, factors ensuring adequate nutrient intake during lactation, health of the sow and the boar, breed of a purebred sow, or the ease of mating the sow.

Key items in the use of the Delphi technique to arrive at a consensus are discussed.

     

Nutrition for optimizing breeding herd performance.

Modern sows are younger and leaner at time of mating and probably have poorer appetites than sows of 10 to 15 years ago. Therefore, feeding strategies should aim to minimize weight loss and maintain a sow's body condition throughout her reproductive life. The efficiency with which gilts are introduced into the breeding herd is as important in economic terms as is the efficiency with which the sow returns to estrus after weaning. Gilts should be selected at 50 to 60 kg, and fed a 16% protein diet ad libitum until mated at their second estrus, when they weigh 115 to 120 kg and have 17 to 20 mm backfat. Flushing gilts before the onset of second or third estrus increases ovulation rate of restricted gilts to the levels achieved by gilts fed ad libitum. During gestation, maintenance represents 75 to 85% of total energy requirements. The aim should be to achieve 20 to 25 mm backfat at farrowing. Increased feed intake from day 2 to 3 after mating will not increase embryo mortality. Feeding an extra 1 kg feed/sow/day for the last 10 days of gestation increases piglet birth weight slightly and prevents a loss of 1.5 to 2.0 mm of sow backfat. Wherever possible, sows should be fed ad libitum from the day after farrowing until weaning. Reduced feed intake by lactating sows, for whatever reason, results in excessive weight and condition loss. Excessive weight loss in lactation causes extended remating intervals, a lower percentage of sows returning to estrus within 10 days of weaning, reduced pregnancy rate, and reduced embryo survival. Ovulation rate is not affected by level of feed intake in lactation. It has been suggested that sows will have minimum weaning-to-service intervals when they weigh 150 kg or more at weaning. It is likely that the sow must be anabolic for about 10 days before she will exhibit postweaning estrus. The decision when to rebreed is made some time prior to weaning and is mediated by a host of substrates, hormones, and neurotransmitters. Sows with a delayed return to estrus also have a lower pregnancy rate and smaller subsequent litters. If sows lose considerable weight or condition during lactation, a high level of feeding in the postweaning period will improve embryo survival.     

Correlated responses in sow appetite, residual feed intake, body composition, and reproduction after divergent selection for residual feed intake in the growing pig

Residual feed intake (RFI) has been explored as an alternative selection criterion to feed conversion ratio to capture the fraction of feed intake not explained by expected production and maintenance requirements. Selection experiments have found that low RFI in the growing pig is genetically correlated with reduced fatness and feed intake. Selection for feed conversion ratio also reduces sow appetite and fatness, which, together with increased prolificacy, has been seen as a hindrance for sow lifetime performance. The aims of our study were to derive equations for sow RFI during lactation (SRFI) and to evaluate the effect of selection for RFI during growth on sow traits during lactation. Data were obtained on 2 divergent lines selected for 7 generations for low and high RFI during growth in purebred Large Whites. The RFI was measured on candidates for selection (1,065 pigs), and sow performance data were available for 480 sows having from 1 to 3 parities (1,071 parities). Traits measured were sow daily feed intake (SDFI); sow BW and body composition before farrowing and at weaning (28.4 ± 1.7d); number of piglets born total, born alive, and surviving at weaning; and litter weight, average piglet BW, and within-litter SD of piglet BW at birth, 21 d of age (when creep feeding was available), and weaning. Sow RFI was defined as the difference between observed SDFI and SDFI predicted for sow maintenance and production. Daily production requirements were quantified by litter size and daily litter BW gain as well as daily changes in sow body reserves. The SRFI represented 24% of the phenotypic variability of SDFI. Heritability estimates for RFI and SRFI were both 0.14. The genetic correlation between RFI and SRFI was 0.29 ± 0.23. Genetic correlations of RFI with sow traits were low to moderate, consistent with responses to selection; selection for low RFI during growth reduced SDFI and increased number of piglets and litter growth, but also increased mobilization of body reserves. No effect on rebreeding performance was found. Metabolic changes previously observed during growth in response to selection might explain part of the better efficiency of the low-RFI sows, decreasing basal metabolism and favoring rapid allocation of resources to lactation. We propose to consider SRFI as an alternative to SDFI to select for efficient sows with reduced input demands during lactation.     

Effects of pre- and postnatal exposure to garlic and aniseed flavour on pre- and postweaning feed intake in pigs

The low nutrient intake shortly after weaning is a major cause of post-weaning problems. Feed intake after weaning is strongly related to feed intake during lactation. Feed intake during lactation, however, varies considerably between litters. We hypothesised that prenatal and postnatal exposure to certain flavours would increase the intake of feed containing the same flavours pre- and postweaning. Multiparous sows did (n = 17) or did not (n = 14) receive 50 g garlic granulate/powder and 25 g aniseed as daily additive to their diet during the last month of gestation and during lactation. From day 14 of lactation, litters were submitted to intermittent suckling: 12 h separation form the sow each day. During lactation, all litters had 40 g garlic and 20 g aniseed per kg added to their creep feed. After weaning, half of the litters had no additive in their diet. Piglets were weaned at 4 weeks (13 litters) or at 6 weeks (18 litters). At 6 weeks of lactation, litters of which the dam received the flavour in her diet, had a higher feed intake (309 ± 43 vs 233 ± 35 g/p/d) than litters of dams without the flavour, although the difference was not significant. Sow diet had no effect on postweaning feed intake, but postweaning piglet diet did. Late (week 6) weaned litters receiving the flavoured feed had a higher feed intake from 3 to 10 days after weaning (833 ± 38 vs 687 ± 58 g/p/d). Weight gain during the first 10 days after weaning was not affected by sow or pig diets. Feed intake and weight gain shortly after weaning were strongly related to feed intake during lactation (overall R = 0.64, P < 0.05 and R = 0.77, P < 0.05). We conclude that early experience with flavours increases later acceptance and improves adaptation to post weaning conditions.     

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.     

Exploring breeding opportunities for reduced thermal sensitivity of feed intake in the lactating sow

The aims of this study were, first, to evaluate the effects of climatic variables on daily feed intake of lactating sows and, second, to establish whether the response of sows to variation in temperature on feed intake during lactation was heritable. A total of 82,614 records for daily feed intake during lactation were available for 848 sows with 3,369 litters farrowing from January 2000 to December 2007. Climatic parameters available from the nearest weather station were maximum 24 h outside temperature, day length changes, and humidity. Although ambient room temperature was modified at the animal level in the farrowing shed, these climatic variables still had a significant effect on feed intake during lactation. Regression coefficients temperature and humidity were 0.01385 ± 0.00300 (temperature) - 0.00031 ± 0.00009 (temperature(2)) and 0.01443 ± 0.00620 (humidity) - 0.00009 ± 0.00004 (humidity(2)). There was an interaction between temperature and humidity, partly due to the climate control in the farrowing shed. At low temperature, feed intake increased considerably with greater humidity, in contrast to a small reduction in feed intake with greater humidity at high temperature. Day length change was modeled with a cosine function. At the start of autumn (September 21), sows ate 0.36 ± 0.056 kg/d less feed than at the start of spring (March 21). Daily feed intake during lactation was described as a function of days in lactation and as a function of both days in lactation and temperature using random regression models. The average heritability and repeatability summarized over the day in lactation at the mean temperature were 0.21 and 0.69, respectively. Genetic variance of temperature response on feed intake was less than 20% of the day effect. The permanent environmental variance was 2-fold (day) and 4-fold (temperature) greater than the corresponding additive genetic variance. Heritabilities of daily feed intake were greater during the first week of lactation compared with the rest of lactation. The genetic correlation between days decreased as time increased down to about 0.2 between the first and last day in lactation. The genetic correlation between feed intake records at the extreme temperatures decreased to about -0.35. It was concluded that random regression models are useful for research and results may be used to develop simpler models that can be implemented in practical breeding programs. An effect of temperature on lactation feed intake was found even in this climate-controlled environment located in a temperate climate zone. Larger effects are expected in more extreme climatic conditions with less temperature-controlled farrowing sheds.     

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.     

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。     

哺乳母猪采食量的重要性

哺乳母猪采食量低下是当前养猪生产中存在的一大难题,特别是现代瘦肉型品种的哺乳母猪这一问题更为严重。泌乳期母猪采食量低下会对种猪繁殖性能造成有害影响,提高泌乳期采食量将有利于提高母猪繁殖性能和养猪经济效益。本文综述了哺乳母猪的采食量,哺乳母猪采食量低下对繁殖性能的影响,哺乳母猪采食量的影响因素,弥补哺乳母猪采食量不足的营养与饲养措施,哺乳母猪采食量的营养生理调控方法。     

Performance and individual feed intake characteristics of group-housed sows fed a nonstarch polysaccharides diet ad libitum during gestation over three parities

The objective of this experiment was to study the effects of feeding group-housed gestating sows a diet with a high level of fermentable nonstarch polysaccharides (NSP; approximately 45% sugar beet pulp as fed) ad libitum on the development in individual feed intake characteristics and reproductive performance during three successive reproduction cycles. Performance of the ad libitum-fed sows was compared to the performance of sows that were fed a conventional diet restrictedly. Feed intake characteristics during gestation were only measured in the ad libitum-fed sows. One hundred and nineteen sows were assigned to one of two gestation feeding regimens. Gestating sows were fed a conventional Dutch diet restrictedly or a diet with a high level of fermentable NSP ad libitum. During lactation, sows were given free access to a commercial lactation diet from d 6 after parturition onward. The ad libitum-fed sows ate 1.3 kg/d more during gestation than the restrictedly fed sows (P < 0.001), resulting in higher body weight and backfat gains during gestation (P < 0.05). Sows that were fed ad libitum during gestation lost more body weight and backfat during lactation (P < 0.001) than sows that were fed restrictedly during gestation. Feed intake during lactation, however, did not differ between sows that were fed restrictedly or ad libitum during gestation. The numbers of total piglets born, live-born and stillborn piglets, piglet birth weight, weaning-to-estrus interval, and percentage of sows that returned to estrus after first insemination were not affected by gestation feeding regimen. Mean daily voluntary feed intake (as-fed basis) over the three reproduction cycles in the ad libitum-fed gestating sows was 4.2 kg/d. Depending on the number of preceding reproduction cycles during which a sow was fed ad libitum, the maximum voluntary feed intake was reached in Parity 3, 4, or 5 and then remained stable in subsequent parities. Mean daily feed intake of the ad libitum-fed sows increased from wk 2 to 6 of gestation and then decreased to wk 15 of gestation. The mean number of daily visits with feed intake over the three reproduction cycles was 13.8. On average, ad libitum-fed sows spent 90 min/d on eating. This study shows that it is possible to feed gestating sows a diet with a high level of fermentable NSP ad libitum during three successive reproduction cycles without negative effects on reproductive performance.     

The importance of a high feed intake during lactation of primiparous sows nursing large litters

The objective of this study was to investigate whether nursing a large number of piglets has negative effects on lactation and postweaning performance of primiparous sows and whether a greater lactation feed intake can prevent possible negative effects. Data were recorded on 268 ad libitum-fed sows of three genotypes (G1, G2, and G3) in an experiment where litter size was standardized to 8, 11, or 14 piglets during a 4-wk lactation. Compared to G1 and G2, G3 sows were heavier (P < 0.05) and leaner (P < 0.05) at weaning of their litters, lost similar amounts of BW and backfat, and their piglets grew faster (P < 0.05). Compared to G1, feed intake during lactation was higher for G3 sows (P < 0.05), and their risk of a prolonged weaning-to-estrus interval was lower (P < 0.01). Daily feed intake by sows was not affected by litter size in G1 and G3, but it was quadratically affected in G2 (P < 0.05), with a maximum at 10.8 piglets. Backfat loss of the sows increased linearly with litter size (P < 0.05) in G1 and G3. In G2, backfat loss increased only at litter sizes > 9.8 piglets (P < 0.01). Body weight loss of the sow and litter weight gain increased linearly with litter size (P < 0.001). Per extra piglet nursed, sows had a 23% (P < 0.01) higher probability of a prolonged weaning-to-estrus interval. A higher daily feed intake during lactation reduced tissue loss of the sow, increased litter weight gain (P < 0.01), and reduced the probability of a prolonged weaning-to-estrus interval (by 42% per extra kilogram; P < 0.01). Sows with a lower daily body weight loss during first lactation had a larger second litter (1.28 piglets/kg; P < 0.01), and their probability of a prolonged weaning-to-estrus interval was reduced by 61% per kilogram (P < 0.001). With increasing litter size, it is therefore recommended to reduce body weight loss during lactation by stimulating daily feed intake and by genetic selection.     

Effect of roasted or raw peanut kernels on lactation performance and milk composition of swine

A lactation trial involving 105 sows was conducted to determine the effect of 12% roasted or raw, ground, whole, shelled peanuts on sow weight change during lactation, feed intake, piglet and litter weight gain, milk composition, and days to return to postweaning estrus. The trial was conducted using three sow groups during two farrowing seasons, summer (July to September) and winter (December to February). Diets were based on corn plus soybean meal. Diets contained either 5% animal fat or equivalent added fat from 12% roasted or raw, ground, shelled peanuts. The replacement of animal fat by roasted or raw peanuts had no effect (P greater than .20) on sow weight change, average daily feed intake during lactation or days to estrus postweaning, or on piglet weight gain or survival. Milk composition (percentage fat and protein) was not altered (P greater than .20) by source of fat in the summer; however, in the winter, sows fed roasted peanuts had higher (P less than .05) milk fat and protein percentage at 3 d postfarrowing than other treatment groups. At d 7, sows fed 12% roasted or raw peanuts had higher (P less than .05) milk protein than sows fed 5% animal fat. Sows farrowing in the summer had greater (P less than .01) weight loss and consumed less (P less than .05) feed during lactation than sows farrowing in the winter. Sows farrowed in the summer had larger (P less than .05) litters at birth and 14 d postfarrowing and greater (P less than .10) piglet and litter weight gain postfarrowing than those farrowed in the winter.(ABSTRACT TRUNCATED AT 250 WORDS)     

Feeding behavior in primiparous lactating sows: impact of a high-fiber diet during pregnancy

Voluntary feed intake of hyperprolific sows can be insufficient to cover the requirements for milk production and maintenance of body condition. A bulky diet fed during pregnancy is known to prepare sows for an ad libitum feed supply after parturition as shown by the increased feed intake during lactation. The aim of this study was to investigate the feeding behavior of young sows during their first lactation to evaluate the further impact of the feeding experience acquired during pregnancy, through the addition of dietary fiber in the diet. Analysis of the feeding pattern and the profile of feed intake tested the hypothesis that lactating sows would exhibit different feeding strategies depending on the diet during pregnancy. During pregnancy, 24 primiparous sows (Large White x Landrace) were offered either 2.4 kg of a control diet/d containing 3.16% crude fiber or 2.8 kg of a high-fiber diet/d containing 12.42% crude fiber. All sows received 33 MJ of DE/d. From the first day postpartum until weaning, all sows were offered the same lactation diet ad libitum. The feeding pattern during lactation was recorded as ADFI, meal frequency, and meal size. In lactation, the ADFI did not differ according to the treatment. Compared with control sows, high-fiber sows consumed their diet in more (P < 0.05) but smaller meals (P < 0.05). In both treatments, ADFI and the number of daily meals increased over weeks of lactation (P < 0.001). All sows presented a strong diurnal and bimodal feeding activity evolving toward 2 distinct feeding periods occurring from 0500 to 0900 and from 1400 to 1800 and accounting for 0.64 of the total daily feed intake during the third week of lactation. The provision of a fibrous diet during pregnancy pointed out the role of an early feeding experience on the development of feeding behavior during the first reproductive cycle.     

A review of factors influencing litter size in Irish sows

Many factors influence litter size. These include genetics, gilt management, lactation length, parity distribution, disease, stress and boar fertility. In the past 20 years, litter size in Irish sows has increased by only one pig. Born alive figures now average at 11.2 pigs per litter. In this regard, Ireland is falling behind our European competitors who have made significant advances over this time. Denmark, for example, has an average figure of 12.7 pigs born alive per litter and France an average of 12.5. The single area that could be improved immediately is sow feeding. It is important that sows are fed correctly throughout pregnancy. If over-fed during pregnancy, sows will have depressed appetite during lactation. If underfed in pregnancy, sows will be too thin at farrowing. The correct way to feed a pregnant sow is to match her feed allocation to her requirement for maintenance, body growth and growth of her developing foetuses. During lactation, sows should be given as much feed as they can eat to prevent excessive loss of body condition. Liquid-feed curves should be such that lactating sows are provided with a minimum mean daily feed supply of 6.2 kg. A small proportion of sows will eat more and this could be given as supplementary dry feed. Where dry feeding is practised in the farrowing house, it is difficult to hand-feed sows to match their appetite. Ideally ad libitum wet/dry feeders should be used. From weaning to service, sows should once again be fed ad libitum. If liquid feeding, this means giving at least 60 MJ DE (digestible energy) per day during this period. If dry feeding, at least 4 kg of lactation diet should be fed daily. The effort spent perfecting sow feeding management on units should yield high dividends in the form of increased pigs born alive per litter.     

Effect of system of feeding and watering on performance of lactating sows

An experiment was conducted to determine the effects of ad libitum access to feed and water and the option to mix feed and water, all in the same feeder, on the performance of multiparous lactating sows. Feed and water were made available to sows using a self-fed wet/dry (SFWD) or a hand-fed (HF) feed-water system. In the SFWD system, feed and water were dropped into a common trough area of the feeder. The sow determined when and how much of each was dropped. With feed falling onto the flat area of the bottom of the SFWD feeder trough and water falling into the shallow bowl area, and with the 2 areas seamlessly connected, the sow also determined the wetness of the feed consumed. In the HF system, sows were given dry feed twice daily in a J-shaped feeder that was independent of the sow's water source. Sows (n = 114) were assigned to treatments based on parity and genotype. Total feed disappearance per sow during lactation (20 +/- 0.2 d) was greater (P < 0.01) with the SFWD system than with the HF system (120 vs. 110 +/- 4.1 kg, respectively). The SFWD sows had greater (P < 0.01) BW gains during lactation than HF sows (6.2 vs. 0.6 +/- 1.85 kg, respectively). Backfat depth change during lactation did not differ (P = 0.37) between treatments. Likewise, percentage of sows displaying estrus by d 11 post-weaning did not differ (P = 0.51). Piglet weaning BW was greater (P < 0.01) with the SFWD system than with the HF system (6.63 vs. 6.12 +/- 0.22 kg, respectively). Sow average daily water intake and total feed wastage during lactation did not differ (P > 0.66) between treatments. However, sows with the SFWD system wasted less water (P < 0.01) than those with the HF system (15 vs. 232 +/- 12 L, respectively). From a commercial swine production perspective, the difference in waste water volume would result in a significant variation in costs associated with manure storage and distribution. In conclusion, use of a SFWD feed-water system in lactation, which provides sows choices of when to eat, how much to eat, and if dry feed should be mixed with water during consumption, enhances sow appetite, improves litter growth performance, and wastes less water than a HF feed-water system.     

Effects of salinomycin on sow weight change during lactation and on sow reproductive performance

Forty-five gravid cross-bred sows (mean parity 3.3 +/- .3) were randomly allotted to two dietary treatments: corn-soybean mean (CS) or CS plus 60 mg salinomycin per kilogram of diet (CSS). Sows were fed their respective diets through two successive parities with dietary treatment initiated at 100 d postcoitum and continued until weaning of the second successive litter. Therefore, sows fed CSS received salinomycin for 14 d before the first parturition and for approximately 153 d before the second parturition. Daily feed intake was restricted to 2 kg.hd-1.d-1 during gestation and to 3 kg.hd-1.d-1 from weaning to breeding. All sows. had ad libitum access to feed during lactation. Sows were weighed 7 d prior to parturition, at weaning and at breeding. Weaning-to-estrus interval and farrowing interval were recorded for all sows. Litters were weighed at birth and weaning. There were no differences (P greater than .05) between dietary treatments in sow weights before parturition, at weaning or at breeding for either first or second farrowing. The CSS-fed sows lost more weight from weaning to breeding after the first (P less than .03) and second (P less than .05) lactation periods than CS-fed sows. The CSS-fed sows tended to gain more (P = .06) weight during lactation than CS-fed sows. There were no differences (P greater than .05) between treatments in lactation feed intake, weaning-to-estrus interval, farrowing interval, litter size born or weaned, litter weights at birth or at weaning, or in sow culling rate.(ABSTRACT TRUNCATED AT 250 WORDS)