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....     

Lactational and subsequent reproductive responses of lactating sows to dietary lysine (protein) concentration

Gilts (n = 208) were used to evaluate the effect of lysine (protein) intake over three parities on lactation and subsequent reproductive performance. Sows were assigned randomly to one of five experimental diets at each farrowing. The five corn-soybean mealbased lactation diets contained increasing concentrations of total lysine (.60, .85, 1.10, 1.35, and 1.60%) and CP (14.67, 18.15, 21.60, 25.26, and 28.82%). Other amino acids were provided at a minimum of 105% of the NRC (1988) ratio to the lysine requirement. Sows had ad libitum access to their assigned diets from parturition until weaning (19.5+/-.2 d postpartum). All sows were fed a common gestation diet (14% CP and .68% lysine) from weaning to next farrowing. Litter size was standardized by d 3 postpartum to 10 pigs in parity 1 and 11 pigs in parity 2 and 3. Increasing dietary lysine (protein) linearly decreased (P<.05) voluntary feed intake of parity 1 (from 5.4 to 4.6 kg/d), 2 (from 6.5 to 5.8 kg/d), and 3 sows (from 6.8 to 6.2 kg/d). With the increase of dietary lysine (protein) concentration during lactation, litter weight gain responded quadratically (P<.05) in all three parities. Maximal litter ADG was 2.06, 2.36, and 2.49 kg/d in parities 1, 2, and 3, respectively, which occurred at about 44, 55, and 56 g/d of lysine intake for parity 1, 2, and 3 sows, respectively. Increasing dietary lysine (protein) had no effect (P>.1) on sow weight change, weaning-to-estrus interval, and farrowing rate in all three parities and no effect on backfat change in parity 2 and 3, but tended to increase backfat loss linearly (P<.1) in parity 1. A linear decrease of second litter size (total born, from 11.7 to 10.1, P<.1; born alive, from 11.0 to 8.9, P<.01) was observed when dietary lysine (protein) increased during the first lactation. Lysine (protein) intake during the second lactation had a quadratic effect on third litter size (P<.05; total born: 13.3, 11.2, 11.6, 11.9, and 13.6; born alive: 11.8, 10.1, 10.3, 11.2, and 12.4). However, fourth litter size was not influenced by lysine (protein) intake during the third lactation. These results suggest that the lysine (protein) requirement for subsequent reproduction is not higher than that for milk production. Parity influences the lysine (protein) requirement for lactating sows and the response of subsequent litter size to previous lactation lysine (protein) intake.     

Effects of pre‐weaning dietary substitutions on plasma insulin and glucose profiles in primiparous sows

The objective of this study was to investigate the effects of substituting 1 kg of a standard lactation diet with 1 kg of a sugar‐rich (15.75 DE MJ/kg) or fat‐rich (23.85 DE MJ/kg) diet during late lactation on blood glucose and insulin changes in primiparous sows. During a 4‐week lactation period, 21 primiparous sows were fed to appetite with a standard lactation diet (14.10 DE MJ/kg). At 9 days before weaning, sows were assigned to a control (C, n = 7), fat (F, n = 6) or sugar (S, n = 8) treatment. During the treatment period (from 8 days before weaning until weaning), 1 kg of the lactation diet was substituted with 1 kg of a sugar‐rich or fat‐rich diet for S and F sows. At 3 days before weaning, serial blood samples were collected for a total of 228 min around feeding to establish pre‐ and postprandial plasma glucose and insulin concentrations. Preprandial plasma glucose and insulin concentrations did not differ between treatments (p > 0.05); however, mean plasma glucose and insulin concentrations were higher for S compared to F (p < 0.05) and intermediate for the C sows. Postprandial plasma concentrations of glucose and insulin were higher for the S sows than for C and F sows (p < 0.05). Sow body weight loss during late lactation did not differ between treatments (p > 0.05). The results from our study suggest that a sugar‐enriched diet during the last week of lactation elevates circulating glucose and insulin concentrations and may potentially improve post‐weaning fertility in primiparous sows.     

Effects of dietary star anise (Illicium verum Hook f) supplementation during gestation and lactation on the performance of lactating multiparous sows and nursing piglets

Thirty‐two sows were allocated to four treatments to evaluate the effect of dietary star anise (SA) supplementation during gestation and lactation on the lactational performance of sows. At 85 days of gestation, sows were randomly allotted to one of two diets supplemented with 0.5% SA or basal diet. After farrowing, sows were further allotted to one of two lactation diets supplemented with 0.5% SA or basal diet. On a weekly basis, body weight (BW) of sows and piglets was measured. Blood and milk samples were obtained from the sows and piglets. Number of days from weaning to estrus, milk yield and feed intake were also recorded. Weight gain of piglets from sows fed the SA‐supplemented diet during lactation was greater between days 7 and 14, days 14 and 21 and the overall experimental period compared with control groups. Supplementation of SA during lactation improved weaning weight of piglets, milk yield and average daily feed intake (ADFI) of sows. The SA diet increased concentrations of insulin‐like growth factor‐1 (IGF‐1) in ordinary milk and prolactin (PRL) in serum of sows. In conclusion, this study has indicated the beneficial effects of dietary SA addition in improving the lactation performance of sows.     

Pea starch meal as a substitute for cereal grain in diets for lactating sows: The effect on sow and litter performance

The major by-product from the production of pea protein concentrate is pea starch, and this starch can be an alternative source of starch compared to for instance starch from wheat in diets for pigs. However, differences in energy utilization between pea starch and cereal starch could affect the animals' production performance. In this study data from 100 Norwegian Landrace x Yorkshire sows was collected to investigate if inclusion of 20% pea starch meal (Pisum sativum L) in diets for lactating sows affected sow and litter performance. Two cereal grain based diets were formulated, but in one of the diets part of the wheat inclusion was replaced with pea starch meal. Data collection included registrations of sow daily feed consumption, individual weight and backfat measures, litter weights, measurement of blood glucose level after feeding and reproductive performance. Sows offered the pea diet had a higher average daily (P<0.0001), weekly (P<0.01) and total feed consumption (P<0.0001) during lactation. They also had a lower weight loss during the first three weeks of lactation (P<0.001). During the last two weeks of lactation sows in both groups were on average gaining weight, but the sows offered the control diet had the highest gain in this period (P<0.05). There was a tendency for a higher backfat loss in the pea group during the first three weeks of lactation (P=0.10), but no difference was found in overall backfat loss between treatments (P>0.05). Dietary treatment did not affect litter performance during lactation (P>0.05). The weaning-to-service interval was higher among the first parity sows offered the pea diet compared to the first parity sows offered the control diet (P<0.05). Blood glucose was not affected by dietary treatment within the chosen timeframe of this study (P>0.05). This study shows that pea starch meal can be used as an alternative source of starch in diets for lactating sows. The sows offered the pea diet had the highest feed consumption during lactation, and although this was not reflected in higher weaning weights, it was reflected in an improved body condition at weaning.     

Elevating glucose and insulin secretion by carbohydrate formulation diets in late lactation to improve post‐weaning fertility in primiparous sows

Primiparous (P1) sows commonly lose excessive body reserves to meet energy requirements for maintenance and milk production during lactation, and consequently, post‐weaning reproductive performance may be compromised. The present studies determined whether ad libitum feeding a glucogenic carbohydrate diet (CHO) during late lactation could stimulate insulin and glucose secretion (experiment 1) and improve subsequent litter size (experiment 2). For experiment 1, 15 P1 sows, and for experiment 2, 99 P1 sows (198.5 ± 2.7 kg) were allocated randomly according to suckled litter size (≥10 piglets), either to a CHO diet (14.3 MJ DE/kg, 19.8% crude protein) or a standard lactation diet (control; 14.2 DE MJ/kg, 19.5% crude protein) at 8 days before weaning. The CHO diet aimed to provide glucogenic content (extruded wheat, dextrose and sugar) as energy sources instead of fat sources without changing total dietary energy. Pre‐prandial plasma glucose and insulin concentrations were not influenced by treatments. However, post‐prandial plasma glucose and insulin concentrations and their peaks were both higher (p < .05) compared to the control treatment. Body weight loss during lactation was relatively low at 3%–4% for both treatments and did not differ between control and CHO treatments (?7.6 ± 1.6 vs ?5.4 ± 1.2 kg; p > .05). Second litter size was not influenced by diet (p > .05), but the weaning‐to‐mating interval was shorter in CHO sows (p < .05). This study demonstrates that providing an enriched CHO diet in late lactation did influence post‐weaning follicle growth but did not improve subsequent litter size. This may be due to the primiparous sows in this study not experiencing severe negative energy balance and there was no second litter syndrome in this farm which limited the ability of diet to improve sow fertility.     

Effect of dietary folic acid supplementation on sow performance through two parities

One hundred fifty-three gilts were maintained in three breeding groups and fed gestation-lactation diets supplemented with either 0 (control), 1.65 or 6.62 mg of supplemental folic acid/kg of diet for two consecutive parities. Serum folate concentrations of sows were linearly (P less than .05) increased by dietary additions of folic acid during both gestation and lactation, but serum glucose and urea concentrations were unaffected by treatment. Serum folate concentrations decreased from breeding to d 60 and 90 of gestation and then increased through lactation for all treatments. Number of pigs born and live pigs at birth, d 14 and d 21 were quadratically (P less than .05) increased by folic acid additions. Average pig weights were similar among treatments (P greater than .10) on both d 0 and 14 of lactation but were less (P less than .01) than the other treatment groups on d 21 for pigs from sows fed the 1.65 mg/kg treatment. Litter weights were quadratically (P less than .01) increased on d 0 and d 14 by folic acid supplementation. Sow weight gain and backfat thickness loss were unaffected by treatment during gestation (P greater than .06); sow weight loss and backfat thickness loss increased quadratically with increasing level of folic acid during lactation (P less than .06 and .05, respectively). More control sows exhibited estrus by d 7 postweaning than sows receiving folic acid supplementation in parity I (P less than .05); however, no differences (P greater than .10) were detected among treatments by d 14, nor were any differences observed by d 7 in parity II. Conception rate was unaffected by folic acid additions. Dietary folic acid supplementation improved sow reproductive performance by increasing the number of pigs born alive.     

The effects of branched-chain amino acids on sow and litter performance

Sows (n = 306; PIC, Line C-19; average parity 2.1) were used to evaluate the interrelationship between valine, isoleucine, and leucine on sow and litter performance. Our objective was to determine whether the increase in litter weaning weight associated with added dietary valine is specific for valine or a result of the total branched-chain amino acid (i.e., isoleucine and[or] leucine) concentration of the diet. Eight dietary treatments (36 to 41 sows/treatment) were arranged as a 2 x 2 x 2 factorial with two levels of valine (.80 and 1.20%), isoleucine (.68 and 1.08%), and leucine (1.57 and 1.97%). This provided total branched-chain amino acid levels of 3.05, 3.45, 3.85, and 4.25%. The lowest level of each branched-chain amino acid was similar to that in a .90% lysine corn-soybean meal diet containing .15% L-lysine HCl. Amino acids other than valine, isoleucine, and leucine met or exceeded their suggested estimates relative to lysine using ratios derived from the National and Agricultural Research Councils. Average number of pigs on d 2 of lactation was 11.2, and average lactation length was 20.9 d. Number of pigs weaned (x = 10.6), sow ADFI (x = 5.85 kg), and sow weight loss (x = 4.25 kg) were not affected by dietary treatment (P > .10). Sow backfat loss (P < .02), litter weaning weight (P < .04), and litter weight gain from d 2 to weaning (P > .05) increased as dietary valine increased. Litter weight at weaning and litter weight gain were not affected by dietary isoleucine (P > .80) or leucine (P > .60). Sixteen or 17 sows per treatment (129 total) were milked manually on d 14 to 16 of lactation. Increasing dietary valine tended to increase milk urea N (P < .07) but did not affect milk DM, CP, fat, lactose, or ash. Increasing dietary isoleucine or leucine had no effects on milk composition. These results confirm the importance of dietary valine for increased litter weaning weight, independent of either additional dietary leucine or isoleucine.     

The influence of gestation feeding strategy on body composition of gilts at farrowing and response to dietary protein in a modified lactation

Previous experiments have indicated that reproductive function in lean, modern genotypes may be more dependent on body protein mass than, as previously believed, on body lipid reserves. This was investigated in a 3 x 2 factorial arrangement of treatments, involving 60 first-parity sows, comparing three pregnancy feeding strategies and two lactation diets. During pregnancy, sows were fed either a basal diet (5 g lysine/kg, 13 MJ of DE/kg [C]) or the same quantity of basal diet + energy source [E], or additional basal diet supplying both protein and energy [A]. The level of supplement for E and A was adjusted weekly to achieve a backfat thickness measurement (P2 position) of 28 mm at farrowing. Isoenergetic lactation diets were fed to appetite and provided either high (180 g CP/kg, 9 g lysine/kg [H]) or low lysine (120 g CP/kg, 6 g lysine/kg [L]). From d 21 of lactation, sows were separated from their litters and housed next to a boar for 8 h each day; final weaning occurred on d 31. Pregnancy treatment differences in backfat and weight were achieved, with C sows having less backfat on d 1 of lactation than E and A sows (E = 28.1, A = 28.0, C = 22.7 kg, P < 0.001). Sows fed additional basal diet were heavier than E sows, which were heavier than C sows (E = 190, A = 201, C = 178 kg, P < 0.001). Average feed intake over lactation showed a pregnancy feeding effect, with E sows eating less than A or C sows (E = 4.9, A = 5.2, C = 5.4 kg/d, P < 0.005). Total lactation weight loss was affected by pregnancy feeding (E = 18.0, A = 19.0, C = 8.4 kg, P < 0.05) and by lactation diet (L = 19.0, H = 11.3 kg, P < 0.05), whereas total lactation backfat loss was affected only by pregnancy treatment (E = 6.9, A = 6.5, C = 4.6 mm, P < 0.05). No pregnancy treatment or lactation diet effects were observed for litter performance. Lactation diet affected weaning-to-estrus interval, with more sows on the H diet coming into estrus within 6 d of partial weaning (P < 0.05), but there was no pregnancy treatment effect. Therefore, voluntary feed intake during lactation was suppressed by increased fat reserves at a limited body protein mass but not when body protein mass was also increased. Partial weaning-to-estrus interval was increased by reduced dietary protein.     

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   

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 Lactation Diet Fat Level on Sow and Litter Performance

The primary objective of this study was to determine the effects of supplemental dietary fat during lactation on sow BW, sow backfat thickness, sow feed consumption, litter size, and pig growth rate. Dietary treatments included 0, 3, 6, and 9% supplemental low acid yellow fat in a traditional corn-soybean meal basal lactation diet. A total of 160 Landrace and crossbred sows (approximately 40 per treatment) were included in the study. Sows fed 3 and 6% supplemental fat had greater (P<0.10) average backfat thickness at weaning. Sow weight change and feed consumption were inconsistent among dietary fat levels. Dietary fat level during lactation did not affect number of pigs born alive or number of stillborns. However, the 9% fat level was associated with more mummified pigs at birth. Number of pigs weaned was greater for the 0% supplemental fat than for the 9% fat level. The largest average pig weights at 21 (5.8±0.29 kg) and 28 (7.48±0.38) d of age were those from sows fed the 3% added fat diet. Sows with ≤25.4 mm backfat at farrowing had more pigs born alive (P<0.05), had less backfat at 21 and 28 d of lactation (P<0.05), and consumed more feed during wk 2 and 3 of lactation. Of all sows fed the control diet, sows with >25.4 mm backfat at farrowing consistently had heavier pigs throughout the lactation phase (P<0.05). Backfat loss during lactation was lower (P<0.05) for sows with ≤25.4 mm at farrowing within all dietary treatments. Consistent significant differences were not observed in sow weight loss or feed consumption between low and high backfat sows for each dietary treatment. Sow backfat loss during lactation is dependent on body condition at farrowing, in that, fatter sows at farrowing have greater backfat loss during lactation. Sows with ≤25.4 mm of backfat at farrowing responded to added dietary fat treatments and produced heavier pigs throughout the lactation period.     

Influence of dietary fat source on sow and litter performance,colostrum and milk fatty acid profile in late gestation and lactation

The objective of this study was to investigate the effects of dietary supplementation with various fat sources (3.8–3.9% of diet) during late pregnancy and lactation on the reproductive performance, fatty acids profile in colostrum, milk and serum of sow progeny. A total of 80 multiparous sows were randomly fed a control (adding no oil), palm oil (PO), fish oil (FO) or soybean oil (SO) supplemented diet from 90 days of pregnancy to weaning. Supplementation of FO increased litter size of weak piglets, compared with the control‐fed sows (P < 0.05). Dietary FO and SO supplementation, enhanced the weaning survival rate, litter weaning weight, litter weight gain and fat content in milk (P < 0.05). The highest immunoglobulin (Ig)G and IgM levels in colostrum and milk were observed in the FO group (P < 0.05). Meanwhile, the highest concentration of C22:5 (n‐3) and C22:6 (n‐3) in colostrum, milk and piglet serum was observed in the FO group (P < 0.05). Taken together, dietary inclusion of FO or SO improved growth performance of nursing piglets by increasing milk fat output, and FO consumption by sows might benefit the piglets via increasing n‐3 polyunsaturated fatty acid availability and immunoglobulins (IgG and IgM) secretion.     

Effects of additional starch or fat in late-gestating high nonstarch polysaccharide diets on litter performance and glucose tolerance in sows

The effects of feeding additional starch or fat from d 85 of gestation until parturition on litter performance and on glucose tolerance in sows that were fed a diet with a high level of fermentable nonstarch polysaccharides (NSP) were studied. The day after breeding, 141 multiparous sows were assigned to the experiment. At d 85 of gestation, sows were assigned to the treatments. Sows were fed 3.4 kg/d (as-fed basis) of a high-NSP diet or the same quantity of the high-NSP diet and an additional 360 g of starch (from wheat starch) daily, or the same quantity of the high-NSP diet and an additional 164 g of fat (from soybean oil) daily. During lactation, all sows were given free access to the same lactation diet. Approximately 1 wk before the expected time of parturition, an oral glucose tolerance test was performed in 38 randomly chosen sows by feeding pelleted glucose (3 g/kg BW0.75). Blood samples for glucose analyses were taken at -10, 10, 20, 30, 40, 50, 60, 70, 80, 90, 105, and 120 min after glucose was fed. The supply of additional dietary starch or fat did not increase piglet birth weight or total litter weight at birth. Sows that were fed the high-NSP diet had more (P = 0.097) live-born piglets and fewer (P = 0.084) stillborn piglets than did sows that were fed additional fat, whereas sows that were fed additional starch were intermediate for these variables. Piglet mortality after birth was not affected by dietary treatment. Body weight and backfat gains in the last month of gestation were higher for sows fed additional starch or fat than for sows fed the high-NSP diet (P < 0.001 and P = 0.017, respectively). Feed intake in lactation was greatest by sows fed the high-NSP diet, least by sows fed additional starch at the end of gestation, and intermediate by sows fed additional fat (P = 0.099). The differences in lactation feed intake did not result in differences in BW and backfat losses during lactation. Sows that were fed additional fat had the greatest glucose area under the curve (P = 0.044), indicating that these sows were less tolerant to glucose. In conclusion, feeding additional energy (starch or fat) in late-gestating sows that are fed a high-NSP diet did not increase litter weight at birth or piglet survival, but did increase maternal gain. Feeding sows additional energy from fat might induce glucose intolerance, whereas feeding sows additional energy from starch did not induce glucose intolerance.     

Effects of feeding sows fat or fructose during late gestation and lactation

The effects of dietary fat or fructose supplementation during late gestation and lactation on sow milk production and composition and on progeny were examined. On d 88 of gestation, 24 sows were allotted by parity to three dietary treatments (eight sows/treatment). Treatments were 1) a 12.5% crude protein, corn-soybean meal control, 2) the control + 10% added fat or 3) the control + 23% high fructose corn syrup. All treatments were fed to supply 1.82 kg/d of the control diet from d 89 of gestation to parturition with sows in treatments 2 or 3 receiving .18 kg of additional fat or .53 kg of additional high fructose corn syrup, respectively. Feed was gradually increased from d 1 to 7 of lactation to 4.54 kg/d of the control diet (plus .45 kg of added fat and 1.33 kg of added fructose for treatments 2 and 3) and remained at these levels for the remainder of the 21 d lactation period. All treatments were iso-nitrogenous; treatments 2 and 3 were iso-caloric. Litter birth weights, number of pigs born alive, weaning weights and piglet survival rate were not affected by sow treatment. Stillbirths were less (P less than .05) for sows fed fat. Lipid content of milk 24 h post-farrowing was greater (P less than .05) from sows fed fat compared with sows fed fructose. Milk production estimates indicated that multiparous sows fed fat produced more (P less .05) milk than sows fed the control diet. On d 112 of gestation and d 15 of lactation, serial blood samples were drawn to monitor sow response to a glucose challenge (1 g/kg body weight).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of nutrient supply, plasma metabolites, and nutritional status of sows during transition on performance in the next lactation

The aim of the present study was to evaluate the effects of nutrient supply, plasma metabolites, and nutritional status of sows during the transition from gestation to lactation on performance of piglets during the colostral period and throughout lactation. Forty second-parity sows were fed 1 of 4 gestation diets containing a different quantity of dietary fiber (171 to 404 g/kg of DM) from mating until d 108 of gestation. From d 108 of gestation until weaning (d 28 of lactation), sows were fed 1 of 5 lactation diets with a different quantity of dietary fat [3 or 8% with different proportions of medium- (MCFA) and long-chain fatty acids (LCFA)]. Blood was obtained by jugular venipuncture on d 108 and 112 of gestation and on d 1 of lactation, and concentrations of plasma glucose, NEFA, lactate, acetate, propionate, butyrate, and fatty acids were analyzed. Piglet growth and mortality were noted throughout lactation. Piglet mortality during the colostral period (0 to 24 h) was affected by the lactation diets and was positively related to sow backfat (d 108) and plasma lactate (d 112) and negatively related to mean piglet birth weight (P < 0.05). Mean piglet live BW gain (LWG) was recorded in the periods 0 to 24 h, 7 to 10 d, 14 to 17 d, and 17 to 28 d relative to parturition as indirect measures of colostrum yield (0 to 24 h), milk yield in early lactation (d 7 to 10), and at peak lactation (d 14 to 17 and d 17 to 28). Effects of gestation and lactation diets on studied sow traits were tested on selected days during the transition period and the next lactation, and tested statistically on separate days. The LWG in the colostral period was positively correlated with mean piglet birth weight (P < 0.001), plasma concentrations of propionate and MCFA (P < 0.05), and plasma acetate and butyrate (P < 0.1) on d 1 of lactation. The LWG in early lactation was inversely correlated with plasma lactate on d 108 (P < 0.05), plasma glucose on d 112, and backfat thickness on d 108 (P < 0.10). The LWG at peak lactation was positively correlated with MCFA intake of the sow on d 113 to 115 and backfat thickness on d 108 during the transition, and negatively correlated with intake of LCFA and ME intake on d 108 to 112 (P < 0.05). In conclusion, feeding and body condition of sows during the transition from gestation to lactation is important for neonatal piglet survival, lactation performance of sows, and piglet growth during the next lactation.     

Plasma Leptin,Ghrelin and Indexes of Glucose and Lipid Metabolism in Relation to the Appearance of Post‐Weaning Oestrus in Mediterranean Obese Sows (Iberian Pig)

Iberian pig is the most abundant Mediterranean swine. The lack of knowledge of the reproductive physiology of Mediterranean genotypes, with predisposition to obesity, led us to evaluate the influence of body condition and metabolic status at weaning on the resumption of follicular growth and the appearance of post‐weaning oestrus. Females failing to display post‐weaning oestrus showed a high decrease in backfat mass during lactation; backfat depth at weaning was therefore lower than in sows becoming in oestrus. Females not bearing oestrus behaviour showed lower plasma leptin levels and higher ghrelin concentrations at weaning. Moreover, these sows evidenced dyslipidemic profile (increased triglyceridemia and cholesterolemia) and mobilization of fat reserves. Hence, changes in metabolic regulation of Iberian pigs may originate large effects on the resumption of ovulatory activity after weaning.     

Duration of lactation,endocrine and metabolic state,and fertility of primiparous sows

The objectives of this study were to determine factors affecting the reproductive performance of primiparous sows early weaned (EW; n = 35) at d 14 or conventionally weaned (CW; n = 35) at d 24 of lactation. Sow BW and backfat were recorded at farrowing, weekly until weaning, and at standing heat. Feed intake was controlled throughout lactation to standardize nutritional effects on subsequent reproductive performance. Litter size was standardized across treatments within 48 h after farrowing, and litter weight was recorded until weaning. In subsets of sows, blood samples were collected from 10 h before to 10 h after weaning, and then every 6 h until ovulation. Sows were heat checked twice daily and bred at 24-h intervals during standing heat using pooled semen. Ultrasonography every 6 h determined time of ovulation. Sows were either slaughtered within 24 h after ovulation to assess ovulation rate, fertilization rate, and embryonic development in vitro, or at d 28 of gestation to determine ovulation rate and embryonic survival. Compared with CW sows, EW sows had more backfat at weaning (15.9 +/- 0.5 vs. 14.7 +/- 0.5 mm; P < 0.001). Also, CW sows tended to lose more BW and to have lower IGF-I concentrations, indicating poorer body condition. Duration of lactation did not affect ovulation rate (EW = 17.6 +/- 0.7; CW = 18.7 +/- 0.6), fertilization rate (EW = 96.0 +/- 2.2; CW = 88.2 +/- 4.7%), or embryo survival to d 28 (EW = 62.5 +/- 4.5; CW = 63.1 +/- 5.0%). There was a marginal effect of duration of lactation on weaning-to-estrus interval (EW = 120 +/- 3; CW = 112 +/- 3 h; P < 0.06) and duration of estrus (EW = 52.4 +/- 2.3; CW = 46.3 +/- 2.2 h; P < 0.08). Overall, embryonic survival, not ovulation rate, seems to be the limiting factor for potential litter size in the second parity. Although fertility in both EW and CW sows studied was compromised, endocrine and metabolic data indicate that the mechanisms affecting reproductive performance may differ between the two weaning systems. The LH, FSH, and estradiol data from the EW sows are characteristic of animals with limited follicular development and incomplete recovery of the hypothalamic-pituitary-ovarian axis; consequently, the integrity of the uterine environment may be adversely affected and limit embryonic survival. In CW sows, variability in metabolic state seemed to be the key factor limiting the fertility, again adversely affecting embryonic survival.     

分娩与断奶背膘厚度对猪繁殖性能的影响研究

为研究母猪分娩与断奶时背膘厚度对繁殖性能的影响,使用A超测定母猪分娩及断奶时的背膘厚度,根据分娩时背膘厚度将试验动物分为1组（X＜10 mm）、2 组（10 mm≤X≤14 mm）、3 组（X＞14 mm）,根据断奶时背膘厚度将试验动物分为A组（X＜7 mm）、B组（7 mm≤X＜10 mm）、C组（10 mm≤X＜13 mm）、D组（13 mm≤X＜16 mm）、E组（X≥16 mm）,又根据母猪哺乳期间损失的背膘厚度分为Ⅰ组（X＜3 mm）、Ⅱ组（3 mm≤X≤6 mm）、Ⅲ组（X＞6 mm）,用方差分析比较各组繁殖表现,并建立了发情间隔对背膘厚度的回归方程。结果表明,分娩时产死胎母猪的比例2组是10.5%,在3组中最小;断奶后平均发情间隔C组显著低于其他各组(P＜0.05);哺乳期间背膘损失最大的Ⅲ组母猪平均发情间隔为8 d,显著高于Ⅰ组、Ⅱ组(P＜0.05)。表明分娩与断奶背膘厚对母猪繁殖性能有显著影响,膘情适中的母猪有最好的繁殖表现,并建立了回归方程Y=31.787－6.169X +0.440X²－0.009X³,用于预测母猪发情配种日期。     

Should weaning be the start of the reproductive cycle in hyper-prolific sows? A physiological view

Normally, sows are in anoestrus during lactation and start their new cycle at the day of weaning. Modern hybrid primiparous sows that suckle large numbers of piglets may lose substantial amounts of body reserves during lactation. This compromises follicle development during lactation. As modern sows have short weaning-to-oestrus intervals, these compromised follicles are recruited for ovulation directly after weaning, resulting in lower ovulation rates and lower embryo survival. Postponing or skipping first oestrus after weaning in primiparous sows may help to limit the negative consequences of lactation on subsequent reproduction. Multiparous sows may have very high litter sizes, especially after long lactations as applied in organic sows. These high litter sizes compromise piglet birthweight and survival and subsequent performance. Inducing lactation oestrus in multiparous sows may help to limit litter size and improve piglet survival and performance. This study discusses physiological and reproductive effects of extending the start of a new pregnancy after lactation in primiparous sows and induction of lactation oestrus in multiparous sows. We thereby challenge the view that weaning is an ideal start for the reproductive cycle in modern sows.