Influence of gestation energy level on the production of Large White x Landrace sows

Sixty-four Large White x Landrace primiparous sows were utilized to evaluate the influence of feeding 6 vs 9 Mcal ME/d during gestation on reproductive performance. The sows remained on their respective gestation diets for four parities if they successfully farrowed, rebred and conceived. Sows fed 9 Mcal ME/d gained more weight (P less than .05) through the gestation period during parities 1 and 2 and were heavier (P less than .01) on d 110 of gestation for combined parities. Lactation weight loss was greater (P less than .05) for the sows fed 9 Mcal ME/d, resulting in similar weights at weaning. Ultrasonic backfat measurements were greater (P less than .01) on d 110 of gestation for sows fed 9 Mcal ME/d during parity 1 and remained higher (P less than .01) through the fourth-parity gestation. Although sow weaning weights were similar, sows receiving 6 Mcal ME/d scanned less backfat thickness. Gestation treatment significantly affected consumption of a common lactation diet provided ad libitum. Sows fed 6 Mcal ME/d during gestation consumed an average of 22 kg more feed (P less than .01) during lactation than those sows receiving 9 Mcal ME/d. Litter performance as measured by number and weights of pigs born alive and weaned was not altered (P greater than .10) by gestation energy intake. Days to return to estrus and the number of sows remaining in the study for four parities were similar (P greater than .10) between the two treatment groups. The number of farrowings for the four parities totaled 164, with 83 and 81 farrowings for the sows fed 6 and 9 Mcal ME/d, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of lactation and rebreeding phase energy intake on primiparous and multiparous sow performance

Fifty-three primiparous sows were used to study the effects of a high-energy, fat-supplemented diet on sow lactation and rebreeding performance. Sows received either a low [Lo, 12.5 Mcal metabolizable energy (ME)/d] or high (Hi, 16.0 Mcal ME/d) energy sorghum-soybean diet during a 28-d lactation. At weaning, sows were randomly allotted, within lactation treatment, to a low (lo, 5.54 Mcal ME/d) or high (hi, 9.61 Mcal ME/d) energy sorghum-soybean diet until the day of first postweaning estrus. Primiparous sows fed Lo weaned larger (P less than .05) litters than sows fed Hi; however, average pig weight was not affected by lactation treatments. Primiparous sows fed Hi had more backfat at weaning (P less than .01) than Lo sows. In contrast, sow weight was not affected by dietary treatments. Neither lactation nor rebreeding treatments influenced days to rebreeding; however, an interaction (P less than .01) was observed. Mean days from weaning to rebreeding for Lolo, Lohi, Hilo and Hihi sows were 10.0, 7.6, 6.9 and 17.1, respectively. Forty sows were maintained on the same dietary treatments during their second parity. Sows receiving Lo during their second parity farrowed and weaned more (P less than .05) pigs than Hi sows. Multiparous sows fed Hi nursed heavier (P less than .05) pigs on d 21 of lactation and at weaning compared with Lo sows. Sows fed Hi were heavier (P less than .05) and had more (P less than .01) backfat at weaning of their second litter compared to Lo sows. Days to postweaning estrus were not affected by lactation or rebreeding diets. Mean length of the second parity rebreeding interval for Lolo, Lohi, Hilo and Hihi sows was 6.2, 10.2, 7.0 and 10.5 d, respectively. These results suggest that feeding levels during lactation of 12.5 Mcal ME/d or higher supported adequate rebreeding performance. Postweaning feeding levels did not influence days to first estrus. Feeding a high energy diet continuously throughout the lactation and rebreeding phases in primiparous sows may lengthen the postweaning interval to estrus.     

The addition of ground wheat straw as a fiber source in the gestation diet of sows and the effect on sow and litter performance for three successive parities

A regional experiment was conducted at 8 experiment stations, with a total of 320 sows initially, to evaluate the efficacy of adding 13.35% ground wheat straw to a corn-soybean meal gestation diet for 3 successive gestation-lactation (reproductive) cycles compared with sows fed a control diet without straw. A total of 708 litters were farrowed over 3 reproductive cycles. The basal gestation diet intake averaged 1.95 kg daily for both treatments, plus 0.30 kg of straw daily for sows fed the diet containing ground wheat straw (total intake of 2.25 kg/d). During lactation, all sows on both gestation treatments were fed ad libitum the standard lactation diet used at each station. Response criteria were sow farrowing and rebreeding percentages, culling factors and culling rate, weaning-to-estrus interval, sow BW and backfat measurements at several time points, and litter size and total litter weight at birth and weaning. Averaged over 3 reproductive cycles, sows fed the diet containing wheat straw farrowed and weaned 0.51 more pigs per litter (P 相似文献   

Performance of sows fed high levels of nonstarch polysaccharides during gestation and lactation over three parities

The effect of feeding sows a starch diet or a diet with a high level of nonstarch polysaccharides (NSP) during gestation, lactation, or both gestation and lactation during the first three parities on reproductive performance, body weight, and backfat was studied. Four-hundred and forty-four postpuberal gilts were allotted to a 2 x 2 x 2 factorial experiment. Treatments were diet composition during gestation (including the weaning-to-estrus interval; G-Starch: 274 g/kg of starch and 123 g/kg of fermentable NSP or G-NSP: 86 g/kg of starch and 300 g/kg of fermentable NSP), diet composition during lactation (L-Starch: 293 g/kg of starch and 113 g/kg of fermentable NSP or L-NSP: 189 g/kg of starch and 216 g/kg of fermentable NSP) and group-housing system during gestation (free access stalls or electronic feeding). Both gestation diets were formulated to be isoenergetic. During lactation, sows were given free access to the lactation diets from d 6 after parturition onwards. Body weight and backfat gains during gestation were lower in sows fed the G-NSP diet than in those fed the G-starch diet (P < 0.001). The effects were more pronounced in the electronic feeding system than in the free access stalls. These results indicate an overestimation of the energy value of fermentable NSP. Body weight and backfat losses during lactation were less in sows fed the G-NSP diet during gestation than in those fed the G-starch diet (P < 0.05),which can be explained by a 0.4 kg/d higher (P < 0.001) feed intake during lactation of the sows fed the G-NSP diet. Sows fed the L-NSP diet lost more backfat during lactation than sows fed the L-starch diet (P < 0.05). The number of total piglets born and live-born piglets was 0.5 piglet higher in sows fed the G-NSP diet than in those fed the G-starch diet (P < 0.05). Lactation diet did not affect the number of total piglets born or live-born piglets. This study shows that, although high NSP diets negatively influence body weight and backfat thickness of the sows, it is possible to feed sows a diet with a high level of fermentable NSP diet during both gestation and lactation without negative effects on reproductive performance. Under the conditions of this study, feeding sows a diet with a high level of fermentable NSP during gestation and a high level of starch during lactation seems the most favorable feeding strategy.     

Comparison of three methods of feeding sows in gestation and the subsequent effects on lactation performance

A total of 684 sows from breeding groups over 6 wk was used to compare three methods of feeding during gestation on gestation and lactation performance. Control gilts and sows were fed according to body condition based on a scale of 1 to 5 (1 = thin, 5 = fat). Sows were visually assessed for body condition at breeding and were assigned a daily feed allowance to achieve a BCS of 3 at farrowing. Treatment 2 used feeding levels based on backfat thickness (measured between d 0 and 5 after breeding) and weight at weaning for sows or service for gilts. Feed allowance was calculated to achieve a target backfat of 19 mm at farrowing, and remained constant from d 0 to 101 of gestation. Feed allowances were based on modeled calculations of energy and nutrient requirements to achieve target sow maternal weight and backfat gains. Treatment 3 was identical to Treatment 2, except that feeding pattern was altered for thin sows and gilts (<15 mm at service) in an attempt to reach 19 mm by d 36 of gestation. Sows were weighed at the previous weaning, and gilts were weighed at service, with both weighed again between d 112 and 114 of gestation. Backfat was measured between d 0 and 5, and again between d 108 and 113 of gestation. At farrowing, sows on Treatments 2 and 3 had 19 and 19.1 mm of backfat, respectively, whereas control sows tended to have greater (P < 0.07) backfat (20 mm). On average, sows targeted to gain 6 to 9 mm of backfat failed to reach target gains regardless of feeding method. Feeding sows in gestation based on backfat (Treatments 2 and 3) resulted in a numerically higher proportion of sows in the target backfat range of 17 to 21 mm (40.2, 53.3, and 52.6% for control and Treatments 2 and 3, respectively) at farrowing and a numerically lower percentage of fat sows (>21 mm), but no difference in the percentage of thin sows (<17 mm) compared with feeding based on body condition. In conjunction with this observation, sows fed based on BCS were fed higher (P < 0.05) feeding levels in gestation than were sows fed based on backfat depth. Gestation feeding method had no effect on performance during lactation. Feed intake in lactation was lower (P < 0.05) for high backfat sows (>21 mm) at farrowing compared with sows with <21 mm. The high proportion of sows in the optimal backfat category demonstrates that feeding based on backfat and BW has potential for facilitating more precise feeding during gestation.     

羟甲基丁酸钙盐对妊娠后期-哺乳期母猪繁殖性能、乳成分及仔猪生长性能的影响

文章旨在评估日粮中添加羟甲基丁酸钙盐对妊娠后期到哺乳期母猪繁殖性能、乳成分及仔猪生长性能的影响.试验选择32头胎次接近的二元母猪,随机分为2组,每组4个重复,每个重复4头猪.对照组母猪在妊娠后期和哺乳期饲喂基础日粮,处理组母猪在妊娠和哺乳期饲喂基础日粮+8?mg/kg羟甲基丁酸钙,试验从分娩前6?d到仔猪21?d断奶....     

Energy Metabolism During Late Gestation and Lactation in Muciparous Sows in Relation to Backfat Thickness and the Interval from Weaning to First Oestrus

Ten crossbred, fourth or fifth parity sows were divided into 2 groups - high (H) and low (L) - according to their backfat thickness 9 days before parturition. Body weight, backfat thickness and litter weight were recorded repeatedly during a 5 week lactation period. The length of the interval from weaning to first oestrus was also noted. All sows were fed a commercial diet (11.9 MJ/kg, 14.5% crude protein). During gestation, daily food intake was 2.2 kg/sow, while during lactation it was 3.0 kg/sow plus 0.4 kg/piglet.Blood samples were drawn on day 9 before parturition and on days 2,7,14 and 21 of lactation. The samples were analysed to determine concentrations of glucose, urea nitrogen, creatinine, triglycerides, free fatty acids and beta-hydroxybutyric acid. In both groups, concentrations of free fatty acids and urea nitrogen were low on day 9 before parturition while those of triglycerides were high, indicating anabolism regardless of backfat thickness.During the first week of lactation, concentrations of free fatty acids increased in the H-group but not in the L-group, and concentrations of urea nitrogen were higher in the H-group. These differences, together with the greater loss of weight observed in the H-group, indicate that catabolism of maternal fat and protein depots was more pronounced in the Η-group than in the L-group during this time. On day 14 of lactation, both groups showed equally low concentrations of free fatty acids, decreasing creatinine concentrations and stable triglyceride and urea nitrogen concentrations. Furthermore, weight loss during the second and third weeks of lactation was low in both groups. These facts, taken together, indicate that the catabolic rate was decreasing in both groups during this period. No differences in return to oestrus interval were noted between the groups. The present study indicates that under a restricted feeding regime the catabolic rate during the first week of lactation is higher in sows with higher backfat thickness in late gestation.As lactation progresses, a more balanced metabolism is achieved regardless of backfat thickness, which may tend to reduce differences in return to oestrous interval.     

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.     

Effects of Dextrose Plus Lactose in the Sows Diet on Subsequent Reproductive Performance and within Litter Birth Weight Variation

Effects of dextrose plus lactose in sow’s feed were tested on subsequent reproductive performance and within litter birth weight variation. During the last week of gestation and lactation, sows were either fed a commercial lactation diet (Control: C), or an isocaloric diet containing 25 g/kg dextrose plus 25 g/kg lactose (Treatment: T). In the subsequent weaning‐to‐oestrus interval (WEI), all sows received the same amount of a commercial feed, but T sows were supplemented with 150 g dextrose plus 150 g lactose per day. Weight and backfat changes were recorded as well as litter characteristics during the treatment period and the subsequent parity. No significant effect of treatment was found on the subsequent reproductive performance, including the number of piglets born, although the number of live born piglets was 0.51 larger (p = 0.31) and weight of the live born piglets was 84 g higher in the T sows (p = 0.07) than in the C sows. When sows were categorized in sows with 12 or less and more than 12 total born piglets in the previous litter, treatment of sows with dextrose plus lactose resulted for the group with 12 or less piglets in a strong increase in subsequent total born piglets (13.97), whereas in the untreated sows the subsequent litter size was 11.89. In the group with more than 12 total born piglets, no effect of treatment was found (interaction between previous litter size and treatment p = 0.03). The within litter variation in birth weight in the subsequent litter was numerically lower in the T sows. We concluded that the use of dextrose and lactose during lactation and WEI seems to enhance litter size in sows with low previous litter size and seems to have the potential to reduce the within litter variation in birth weight.     

Value of raw soybeans and soybean oil supplementation in sow gestation and lactation diets: a cooperative study

A cooperative study using 215 sows during two parities (349 litters) was conducted at six stations to determine the effect of raw soybeans in gestation and lactation diets on sow and litter performance. Sows were bred and allotted to fortified corn diets containing either soybean meal (control) or raw soybeans. A corn-soybean meal-soybean oil diet, isocaloric to the raw soybean diet, was included as a third treatment at three stations. All diets contained 14% CP. These diets were fed during both gestation and lactation through two parities. The daily gestation feed intake ranged from 1.8 to 2.3 kg/sow, depending on station. During lactation, the sows were allowed ad libitum access to their respective diets. Gestational weight gain was not influenced by diet, but sows fed raw soybeans consumed less (P less than .01) feed during lactation and had greater (P less than .01) lactational weight loss and their pigs were lighter in weight (P less than .05) both at 21 d and at weaning (varied between 3 and 5 wk of age). Sows fed the diet with supplemental oil had reproductive and lactational performance similar to those fed the control diet. Milk obtained at d 10 to 14 of lactation from sows fed raw soybeans had lower (P less than .05) protein content than milk from sows fed the other two diets, but fat content of the milk tended to be increased by raw soybeans or by added soybean oil. Return to estrus was not affected by diet.(ABSTRACT TRUNCATED AT 250 WORDS)     

妊娠后期营养水平对初产母猪繁殖性能及血液生化指标的影响

为研究妊娠后期营养水平对初产母猪体况、繁殖性能及血液生化指标的影响,本试验选用背膘厚及体重相近的初产杂交母猪36头,按体况和配种时间随机分为3组（Ⅰ、Ⅱ、Ⅲ组）,每组6个重复,每个重复2头母猪,饲喂营养水平依次为维持需要的1.5、2.0和2.5倍的日粮,母猪妊娠81 d时开始试验至母猪分娩结束,试验期33 d。结果显示,分娩时Ⅰ组母猪背膘厚显著低于Ⅲ组（P<0.05）,断奶时各组背膘厚度差异不显著（P>0.05）;Ⅰ组母猪泌乳期背膘损失显著低于Ⅲ组（P<0.05）;Ⅲ组母猪分娩后体重、分娩前体重均显著高于Ⅰ组（P<0.05）,各组母猪妊娠81 d体重及泌乳期失重等差异均不显著（P>0.05）。试验组间窝产仔数、窝产活仔数、断奶个体重及母猪断奶-发情间隔均无显著差异（P>0.05）;Ⅲ组仔猪初生均重、断奶窝重、泌乳期窝增重均显著高于Ⅰ组（P<0.05）。随营养水平升高,Ⅱ、Ⅲ组雌激素水平显著高于Ⅰ组（P<0.05）;各组催乳素和孕酮水平差异不显著（P>0.05）;Ⅰ组甘油三酯水平显著低于Ⅱ、Ⅲ组（P<0.05）;各组尿素氮和葡萄糖含量随营养水平的升高逐渐增大,且差异显著（P<0.05）;Ⅲ组胰岛素含量显著高于I组（P<0.05）;各组总蛋白含量无显著差异（P>0.05）。结果提示,母猪妊娠后期饲喂营养水平为2.0倍维持需要的日粮时可使后备母猪分娩时体况达到标准水平,而饲喂营养水平为2.5倍维持需要的日粮可使母猪产仔性能得到提高。     

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)     

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.     

Effect of feather meal as a source of valine for lactating sows

An experiment was conducted to evaluate feather meal as a source of Val in lactating sow diets. Sows (five farrowing groups; mean parity = 2.34) were allotted to one of two dietary treatments on the basis of ancestry, parity, and weight and date of d 110 of gestation. The treatment diets included 1) corn-soybean meal lactation diet (n = 40) or 2) corn-soybean meal lactation diet with 2.5% feather meal (n = 39). The diets were formulated on an equal Lys basis. All litters were adjusted to 10 pigs within 24 h after farrowing, and all sows weaned at least nine pigs. Sows were bled at 110 d of gestation and at weaning, and serum urea N was determined. Backfat thickness was determined ultrasonically at 110 d of gestation and at weaning. Serum urea N and backfat thickness at d 110 of gestation were used as covariates for serum urea N and backfat thickness at weaning, respectively. The litter response criteria (weaning weight, litter weight gain, and percentage survival) were not affected (P > .10) by feather meal. The sow response criteria (weaning weight, weight loss per day, weaning backfat thickness, change in backfat thickness, ADFI, and days to estrus) were not affected (P > .10) by feather meal. Sows fed feather meal had increased (P < .01) serum urea N and tended (P = .15) to have decreased sow weaning weight. Following the initial analysis of the data, the data set was split into two groups: 1) sows with litters gaining less than 2.17 kg/d (n = 19 and 20 for control and feather meal diets, respectively) and 2) sows with litters gaining more than 2.17 kg/d (n = 21 and 19 for control and feather meal diets, respectively). These two groups were analyzed separately. In sows with litters gaining less than 2.17 kg/d, the litter and sow criteria were not affected (P > .10) by treatment. In sows with litters gaining more than 2.17 kg/d, sow weaning weight was decreased (P < .04) and sow weight loss (P < .02) and serum urea N (P < .01) were increased in sows fed feather meal. Feather meal (as a source of Val) did not improve litter weight gain, but it increased serum urea N.     

Relationship between body fat and postweaning interval to estrus in primiparous sows

Twenty-two primiparous Yorkshire sows were used to determine whether a minimal threshold of body fat exists below which the return to estrus is delayed. A second objective was to examine the relationship between body fat and interval from weaning to estrus in restricted-fed sows. During lactation (28 d), sows received 7, 9, 11 or 13 Mcal of ME daily to produce a range of sow body fatness at weaning. Intake of all dietary essentials except ME was similar for all sows. Litter size was adjusted to 10 pigs for all sows by d 3 postpartum. Each day from weaning to estrus, sows received 110 kcal ME per kg metabolic body weight plus 1,359 kcal ME per sow. Body fat was estimated at weaning and at first postweaning estrus by deuterium oxide dilution. Last rib backfat depth was determined ultrasonically 24 h postpartum and at weaning. Irrespective of dietary ME intake, percentage body fat at weaning (R2 = .24; P less than .05) and first postweaning estrus (R2 = .03; P greater than .50) accounted for only a small portion of variation in interval from weaning to estrus. Likewise, loss of backfat depth during lactation was not an accurate predictor of interval from weaning to estrus (R2 = .24; P less than .05). The low coefficients of determination (less than .25) suggest that body fat is a minor controller of postweaning interval to estrus. In contrast, dietary ME intake during lactation accounted for the largest portion of the variation (R2; = .48; P less than .01) in postweaning interval to estrus. We conclude that timing of postweaning estrus in primiparous sows is not dependent on a minimal threshold of body fat. Furthermore, effects of lactational ME intake on the postweaning interval to estrus are more pronounced than the effects of body fat.     

Effect of feeding thyrotropin-releasing hormone to lactating sows

Two experiments were conducted to assess the effects of feeding thyrotropin-releasing hormone (TRH) during lactation on sows. In Exp. 1, sows were fed 0, 1, 10, 100 or 1,000 mg TRH on d 10.8 +/- .4 (mean +/- SE) after parturition. Blood samples were taken from sows every 30 min from -2 h to 8 h and at 10, 12 and 18 h from feeding. Consumption of 100 or 1,000 mg TRH increased mean serum concentrations of thyroxine (T4; P less than .001), 1,000 mg TRH increased growth hormone (GH; P less than .06) and 100 or 1,000 mg TRH increased prolactin (PRL; P less than .01), but insulin (INS; P greater than .10) was unaffected by TRH. Serum concentrations of T4 were elevated within 2 to 4 h after feeding TRH and remained elevated for 12 to 18 h. Concentrations of GH and PRL began to increase immediately after feeding 100 or 1,000 mg TRH and remained elevated for 6 and 8 h, respectively. In Exp. 2, sows were fed 0 or 200 mg TRH from d 111 of gestation to weaning at 27.1 +/- .3 d of lactation. Consumption of TRH elevated concentrations of T4 at all stages of lactation and increased respiration rate on d 10 and d 20, heart rate on d 20, and milk production on d 20 of lactation. Consumption of TRH did not influence number of pigs born, number born alive, survival rate during lactation, sow body weight, heartgirth, backfat depth, feed disappearance, or milk production on d 10 of lactation. Piglets nursing sows fed TRH were similar in weight to piglets nursing sows not fed TRH on d 0 and 5 of lactation, but they were heavier on d 10 (P less than .07), 15 (P less than .001), 20 (P less than .001) and 27 (P less than .0001). Sows fed TRH took longer (P less than .001) to return to estrus after weaning than control sows. Results indicated that feeding TRH elevated T4, GH and PRL and that feeding TRH for the duration of lactation increased milk production on d 20 of lactation and increased weaning weights, but it delayed estrus after weaning.     

母猪妊娠末期背膘厚度对产仔性能和胎盘脂质氧化代谢的影响

本试验旨在探讨母猪妊娠末期背膘厚度对产仔性能和胎盘脂质氧化代谢的影响,以探索母猪妊娠期脂肪沉积与繁殖性能的关系。本试验度量了846头经产大白母猪妊娠第109天时的背膘厚度,并分为3组,背膘厚度≤18 mm的为第1组(母猪192头),背膘厚度为19~22 mm的为第2组(母猪265头),背膘厚度≥23 mm的为第3组(母猪389头)。记录母猪分娩后的产仔性能,测定胎盘组织中脂质、氧化产物水平及抗氧化酶活性。结果表明:1)尽管母猪妊娠末期背膘厚度对总产仔数、产活仔数及木乃伊数无显著影响(P0.05),但显著影响了死胎数、初生窝重、初生头重和胎盘效率(P0.05)。其中,第2组的初生头重、初生窝重及胎盘效率显著高于其他2组(P0.05);第2组的死胎数显著低于第1组(P0.05),与第3组差异不显著(P0.05)。值得注意的是,母猪妊娠末期背膘厚度显著影响每窝初生重≤0.9 kg的仔猪数和每窝初生重≤1.0 kg的仔猪数(P0.05),第3组的每窝初生重≤0.9 kg的仔猪数和每窝初生重≤1.0 kg的仔猪数均显著高于其他2组(P0.05)。2)在第3组的胎盘组织中,不仅甘油三酯(TG)、低密度脂蛋白胆固醇(LDL-C)及游离脂肪酸(FFA)的水平显著高于其他2组(P0.05),而且丙二醛(MDA)和活性氧(ROS)水平也显著高于其他2组(P0.05),同时超氧化物歧化酶(SOD)活性显著低于其他2组(P0.05)。3)妊娠末期母猪胎盘组织中ROS水平与总产仔数、初生窝重及胎盘效率呈显著负相关(P0.05),而MDA水平与总产仔数呈显著负相关(P0.05)。由此可知,母猪妊娠末期背膘厚度与产仔性能密切相关。妊娠末期维持背膘厚度在19~22 mm,母猪可获得较高的产仔性能;背膘厚度≤18 mm时,会增加死胎数;而背膘厚度≥23 mm时,会引起胎盘组织中脂质过度沉积,从而加剧胎盘氧化应激的发生。     

Hormonal therapy for sows weaned during fall and winter

Sows from five commercial herds were weaned in the fall and winter and used to ascertain the potential application of hormonal therapy to stimulate subsequent litter size born. At weaning sows within parity (1, 2, and 3 through 6) and lactation length classification (early weaned, < or = 14 d; conventionally weaned, > 14 d) were randomly assigned to treatment. Treatments were injection with P.G. 600 (400 IU PMSG with 200 IU hCG) at weaning or no treatment. Sows were individually observed for estrus and mated following protocol for each herd. Breeding, culling, and farrowing data were collected. Treatment with P.G. 600 did not change subsequent rebreeding performance for sows at parity 1 or parities 3 through 6. However, conventionally weaned parity-2 sows treated with P.G. 600 were more likely (P < .05) to return to estrus than conventionally weaned controls (99.0 vs 93.6%, respectively). For parity-1 and parity-2 sows, treatment did not significantly change the likelihood for farrow percentage. However, the likelihood to farrow a litter was greater (P < .05) among P.G. 600-treated sows at parities 3 to 6 that were conventionally weaned (84.4 vs 71.3%, respectively). Subsequent litter birth weight for parity-1 sows treated with P.G. 600 was lower (P < .02) than for controls (15.6 vs 16.6 kg, respectively). Subsequent litter size at birth was not affected by treatment for parity-1 or parity-2 sows compared with controls. However, early-weaned sows at parities 3 through 6 treated with P.G. 600 had more (P < .06) total number born than controls (12.4 vs 10.6, respectively). Treatment with P.G. 600 improved reproductive function within specific parity and lactation length classification for sows weaned in the fall and winter.     

Effect of sow parity and weight at service on target maternal weight and energy for gain in gestation

The objective of this study was to evaluate targeted maternal weight gains in sows by parity group during gestation. Weight and backfat gains during gestation by parity, weight, and backfat groups also were analyzed. The data evaluated were a subset (374 sows) of a larger experiment that compared three methods of feeding sows during gestation on weight and backfat gains and subsequent reproductive performance. Feed allowances were based on modeled calculations of energy and nutrient requirements to achieve target sow maternal weight and backfat gains. Actual backfat gain for gilts and sows was regressed on maternal weight gain and estimated energy available for gain. The regression equations were then used to predict maternal weight gains for target backfat gains for three parity groups (gilts, Parity 1 and 2 sows, and Parity 3 and older sows). For gilts and Parity 1 and 2 sows, much greater target maternal weight gains are required to achieve 6 and 9 mm of backfat gain, whereas Parity 3 and older sows require maternal weight gains similar to those targeted to achieve the desired backfat gain. Given similar energy intake levels above maintenance, gilts gained more weight than multiparous sows, as gain was based more on protein and less on fat and thus was more efficient. Gilts required more maternal weight gain than sows to achieve similar backfat gains due to the higher protein and low fat contents of gain in younger, lighter sows compared with older parity sows. Low-backfat sows that needed to gain large amounts of backfat failed to achieve these large gains. We speculate this failure may be due to lower tissue insulation levels with the low backfat levels and higher activity levels of these sows compared with high-backfat sows. It seems that both parity and weight are individually important factors that influence energy and nutrient requirements for gestation in the modern sow.     

Dietary medium- or long-chain triglycerides improve body condition of lean-genotype sows and increase suckling pig growth

In a field trial conducted on a commercial swine farm, lean-genotype sows (n = 485) were fed diets containing 0 or 10% supplemental fat as either medium-chain triglyceride or choice white grease from d 90 of gestation until weaning (15.5 d). Effects on standard sow and litter production traits were examined together with assessment of sow body condition using live ultrasound. Daily feed intake during lactation was 10% higher in sows consuming diets without added fat (7.2 vs 6.5 kg; P < 0.01); however, lactation ME (23.9 Mcal/d) and digestible lysine (54 g/d) intakes were unaffected (P > 0.10). Sows supplemented with fat were 4 kg heavier on d 109 of gestation (220 vs 224 kg; P < or = 0.01), 1 d after farrowing (210 vs 214 kg; P < or = 0.01), and at weaning (210 vs 214 kg; P < or = 0.01). Expressed as overall gain, this amounted to a 23% increase (0.66 vs 0.86 kg/d; P < or = 0.01) and was accompanied by a 49% increase in backfat (0.82 vs 1.68 mm; P < or = 0.03) from d 90 to farrowing. Changes in sow weight (-0.01 kg/d) and backfat (+4.2 mm) over lactation were minimal and were not affected by fat supplementation (P > or = 0.10). Longissimus muscle area at weaning was slightly greater (44.96 vs 46.2 cm2) in sows consuming fat than in control sows (P < or = 0.05), but changes in longissimus muscle area were not significant from d 90 to weaning (P > or = 0.10). Gestation length, pigs born alive, average birth weight, survival (d 3 to weaning), and days to estrus were not affected by diet (P > 0.10). However, supplemental fat increased pig ADG (192 vs 203 g/d; P < 0.01) and average pig weaning weight (4.3 vs 4.5 kg) at 15.5 d (P < or = 0.02). No differences between the two fat sources were detected. This large-scale study demonstrated that supplemental fat during gestation and lactation effectively improved sow condition and improved suckling pig performance without affecting energy intake during lactation, implying improved efficiency of sow energy utilization.