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。     

Endocrine changes associated with cystic ovarian degeneration in sows.

Endocrine changes in sows with ovarian cysts were determined to be comparable with those in sows in diestrus. Blood samples were collected at frequent intervals from 5 sows affected with cystic ovaries. Concentrations of serum luteinizing hormone, progesterone, estradiol-17 beta, and cortisol were determined by use of established radioimmunoassays. The development of ovarian cysts has been proposed to be associated with a deficiency of luteinizing hormone rather than an intrinsic ovarian abnormality. In contrast, the results of this study demonstrated that tonic and pulsatile luteinizing hormone release were not affected adversely in sows with cystic ovaries.     

Plasma ferritin of sows during pregnancy and lactation

We studied a set of indicators of iron metabolism in sows and new-born piglets: hemoglobin, plasma iron, total iron binding capacity and plasma ferritin. Iron status of seventy-two sows was studied throughout pregnancy and lactation. The results point to mobilization of iron from its storage sites up to the second month of gestation, but no appreciable decrease during the second half of pregnancy. No appreciable mobilization of the iron stores of sows was observed during the lactation period. Nine sows and their 78 piglets were used to compare the status of iron in the sows and the end of gestation with the iron status of the piglets at birth; there was a positive correlation between the mean values of plasma ferritin concentration in the piglets and the levels of plasma ferritin in their mothers.     

Effect of ambient temperature on mammary gland metabolism in lactating sows

Two groups of three multiparous Large White x Landrace sows were used to investigate the direct effect of ambient temperature on mammary gland metabolism. Sows from the first group were exposed to temperatures of 28 degrees C between d 8 and 14 of lactation, and 20 degrees C between d 15 and 21; treatments were reversed in the second group. Four to six d after farrowing, an ultrasonic blood flow probe was implanted around the right external pudic artery and catheters were fitted in the right anterior mammary vein and in the carotid artery. After surgery all sows were fed 3.8 kg/d of a lactation diet. The arteriovenous (AV, mg/L) plasma samples were obtained every 30 min between 0915 and 1545 on d 5 of exposure to ambient temperature; the same day, milk samples were collected at 1630. Additional arterial samples were obtained between 1000 and 1100 on d 1, 4, and 6 of exposure. Milk yield was estimated from the body weight gain of the litter. Elevated temperature tended to reduce BW loss (2.44 vs 1.82 kg/d, P < 0.10), but did not affect milk yield (11.0 kg/d). Glucagon and leptin arterial concentrations increased (12 and 8%, respectively; P < 0.10), but thyroxin and triiodothyronine concentrations decreased (26 and 16%, respectively; P < 0.01) between 20 and 28 degrees C. Expressed as a percentage of total nutrients, AV difference, glucose, amino acids, triglycerides (TG), free fatty acids, and lactate A-V differences represented 60, 20, 11, 8, and 1%, respectively. Exposure to 28 degrees C increased the extraction rate of glucose, TG, and a-amino acid N (13, 8, and 2.5%, respectively; P < 0.10). The extraction rates of essential and nonessential amino acids were not affected by temperature. The right pudic artery mammary blood flow increased (872 vs 945 mL/min, P < 0.05) between 20 and 28 degrees C, whereas milk yield was unaffected by temperature. It is suggested that this apparent inefficiency of the sow mammary gland in hot conditions could be related to an increase of proportion of blood flow irrigating skin capillaries in order to dissipate body heat.     

怀孕母猪和哺乳母猪的理想氨基酸平衡最新研究

<正>对于保育猪和生长猪的理想氨基酸平衡的研究已经做了很多(Fuller等,1989;Chung和Baker,1992;Hahn和Baker,1995;Hahn等,1995;Tuitoek等,1997;Carter等,2000;Kim等,2001a)。生长猪日粮中添加合成氨基酸,以达到理想氨基酸模式,可以降低日粮的粗蛋白质水平,减少氮的排出(Lenis和Schutte,1990;Gatel和Grosjean,1992;Kerr和Easter,1995)。     

母猪妊娠期和哺乳期的理想氨基酸平衡

1摘要 对于限饲条件下的妊娠母猪以及采食量有限的哺乳母猪来说,改善蛋白质利用效率很重要。母猪在妊娠后期维持胎儿和乳腺发育以及在哺乳期促进乳腺生长和产奶的能力不足,特别是在第一个哺乳期。进行一系列研究来测定这些营养需要量以及氨基酸的理想比率,包括：1）胎儿生长;2）妊娠期母猪乳腺生长;3）妊娠母猪母体组织增重;4）哺乳母猪的乳腺生长;5）哺乳期母猪母体组织增重。     

妊娠和泌乳期母猪理想氨基酸平衡

蛋白质是乳蛋白合成的主要原料,也是泌乳母猪日粮的主要限制性营养成分之一,因此提高妊娠母猪和泌乳母猪蛋白质的利用率尤为重要。胎儿和乳房的发育需要母猪提供大量的营养,在哺乳期特别是初产母猪的第一个哺乳期会消耗母体大量的蛋白质。多数研究表明,理想氨基酸模式对母猪的一系列生产有极为重要的意义,包括:1)胎儿的生长发育;2)妊娠母猪乳腺的发育;3)妊娠母体组织发育;4)泌乳期母猪乳腺的发育;5)泌乳期母体组织发育。妊娠母猪的氨基酸需要及理想比例随妊娠期进程而呈动态变化趋势,在各种"理想蛋白质"模式中,均以必需氨基酸与赖氨酸的比例来描述。建议配比量:妊娠0～60d和60～114d母猪回肠可消化赖氨酸需要的推荐量分别为5.57g/d和8.78g/d,其赖氨酸:苏氨酸:缬氨酸:亮氨酸分别为100:79:65:88和100:71:66:95。若母猪在21d哺乳期内体重损失是0和3.3～4.5kg,那么赖氨酸:苏氨酸:缬氨酸:亮氨酸的理想比例分别被推荐为100:59:77:115和100:69:78:123。为了使母猪对饲粮蛋白质的利用效率达到最佳,应该考虑氨基酸需要量和理想比例的动态变化情况。     

Pig weaning weight and changes in hematology and blood chemistry of sows injected with recombinant porcine somatotropin during lactation

Weaning weight of pigs on d 18 to 21 of age was used to determine the effects of recombinant porcine somatotropin (rpST) on lactational performance of their dams. Crossbred Landrace x Yorkshire sows (n = 180, 202 to 270 kg BW) were assigned to receive daily i.m. injections of either 0, 8, or 16 mg of rpST on lactation d 7 to 20. Initially, injections of 16 mg of rpST/d caused 100% mortality (four sows); thus, a dose of 4 mg of rpST/d replaced 16 mg. Subsequently, 5 of 19 and 1 of 17 sows died in response to daily injections of 8 and 4 mg of rpST, respectively, resulting in termination of the experiment. Before termination, 48 sows (16 from each of the 0-, 4-, and 8-mg treatment groups) completed a lactation of 18 to 21 d in duration. Analysis of these data indicated that daily injection of lactating sows with rpST increased (P less than .05) weaning weight of pigs only if they were from litters that averaged greater than or equal to 2.6 kg/pig on lactation d 7. The BW of sows was decreased by rpST (P = .07). Subsequent experiments revealed 1) that rpST-induced death of lactating sows was caused from hemorrhaging of ulcers that developed at the pars esophagea, 2) that there was vacuolation of the liver and kidney of dead sows, and 3) that daily injection of 16 mg of rpST into nonlactating growing pigs (50 to 100 kg BW) for 28 d did not cause death or any observable illness in spite of 100% mortality of lactating sows after two to nine injections.     

Efficacy of different phosphorus supplements for sows during gestation and lactation

This study was undertaken to compare dicalcium, Curacao, and soft ph sophates as supplemental feeding during gestation and lactation. In Exp eriment 1, 37 crossbred sows at 11 months of age were mated and each of 4 groups given an experimental diet. The basal diet was a 16% crude pro tein-fortified corn-soybean meal containing .34% of phosphorus and .72% of calcium. The test diets were fortified with either dicalcium, Curaca o, or soft phosphate to provide .52% of phosphorus. Limestone was given to maintain .72% of calcium. Animals were confined in a concrete feedin g area and fed 1.8 kg of diet per head per day until Day 94 of gestation . At that time the diet was increased to 2.3 kg/day. On Day 109 of gestation animals were moved to farrowing crates until 10 days postpartu m and then to wooden units until weening at 8 weeks. Sows were sacrific ed after 8 weeks lactation, or if they developed posterior paralysis. In this experiment, the different phosphate sources were without observed influence on the livability or performance of pigs up to 8 weeks of age (p less than .05). Gilts receiving no supplemental phosphorus had significantly lower bone ash and phosphorus than did those receiving either of the supplements. Posterior paralysis was observed in 5 of 9 sows fed the unsupplemented diet, in 3 of 9 fed the soft supplemented diet, and in 2 of 10 fed the Curacao phosphate supplement. None fed dicalcium phosphate developed paralysis. The paralysis usually occurred after 6 weeks of lactation and was often accompanied by a fractured femur. In Experiment 2, 70 sows were bred at 10 months of age and fed 1.8 kg of the experimental diets. During 36 days of lactation, phosphorus digestibility, retention, and balance were shown to be lower for those fed only the basal diet. Bone ash, bone phosphorus, and bone strength were lower in those fed the unsupplemented diet. Results of these studies indicate the need for supplemental phosphorus in sow feeding. When feeding dicalcium phosphate or Curacao phosphate the use of over .5% phosphorus in the sow's diet is unnecessary during gestation and lactation.     

Testicular dynamics in Syrian hamsters exposed to both short photoperiod and low ambient temperature

The object of this study was to determine the details of morphological dynamics of spermatogenesis in Syrian hamsters exposed to both short photoperiod and low ambient temperature. Eight-week-old male hamsters, kept in a long photoperiod (14 h L, 10 h D), were transferred to a short photoperiod (6 h L, 18 h D) and kept there for 13 weeks to induce testicular regression. Some hamsters were then transferred from the room at 23 degrees C to that at 5 degrees C (5 degrees C group). Remaining hamsters were continuously kept at 23 degrees C (23 degrees C group). Thereafter, the morphology was examined. As a result, it took only 8 weeks until spermatogenesis recovered in the 23 degrees C group. However, it was not until 20 weeks that spermatogenesis was recognized in the 5 degrees C group. As the regulation of seasonal testicular activity is characterized by coordinated shifts in the relationships among mitosis, meiosis, and apoptosis, the changes in the proliferative and apoptotic activities were examined. Although no significant difference in proliferative activity of spermatogonia between the 5 degrees C and the 23 degrees C groups was confirmed, a notable increase in the rate of apoptosis was observed in the 5 degrees C group. Furthermore, this increase was more salient during the hibernation period. These findings suggest that both cold ambient temperature and hibernation caused the delay of testicular recrudescence and this delay arose from the increase of apoptotic activity but not the change in proliferative activity in spermatogonia in the 5 degrees C group.     

Parturition body size and body protein loss during lactation influence performance during lactation and ovarian function at weaning in first-parity sows

We investigated the effect of body protein mass at parturition and different degrees of body protein loss in lactation on sow performance. In a 2 x 2 factorial arrangement, 77 Genex gilts were fed to achieve either a standard or high body mass at parturition and to lose either a moderate (MPL) or high (HPL) amount of protein in lactation. Pregnant gilts were fed either 24.4 MJ of ME, 266 g of CP, and 11 g of lysine/d or 34.0 MJ of ME, 436 g of CP, and 20 g of lysine/d resulting in divergent (P < 0.01) live weights (165 vs. 193 kg) and calculated protein masses (24.3 vs. 30.0 kg) and slightly different backfat depths (20.0 vs. 22.8 mm; P < 0.05) at parturition. Diets fed during lactation were formulated to deliver 731 g of CP and 37 g of lysine/d or 416 g of CP and 22 g of lysine/d to induce differential body protein mobilization. Sows were slaughtered at weaning (d 26), and the weight of the organs and the lean, fat, and bone in five primal cuts was measured. The external diameter of the eight largest follicles on each ovary was recorded, and the follicular fluid from these follicles was collected, weighed, and analyzed for estradiol. Losses in lactational live weight (26 vs. 20 kg; P < 0.01) and calculated protein mass (17.8 vs. 10.7%; P < 0.001) were greater, and the carcass lean mass at weaning was 10% lighter (P < 0.05) in HPL sows. Backfat (5.1 +/- 0.8 mm; P = 0.29) and calculated fat mass (25.8 +/- 1.5%; P = 0.84) losses did not differ between treatments. Both sow body mass (P < 0.05) and lactation protein loss (P < 0.01) affected litter growth rate. Litter growth rate decreased (P < 0.05) at the end of lactation in HPL sows once these sows had lost 10 to 12% of their calculated protein mass. Ovarian follicular development was most advanced in high body mass sows that lost the least protein; these sows had the heaviest (P < 0.05) uterine weight and highest (P < 0.05) follicular fluid estradiol concentration. Follicular development was least advanced in standard body mass sows that lost the most protein. These sows had the lowest (P < 0.05) muscle:bone ratio at weaning and likely lost the largest proportion of their muscle mass compared with the other treatments. In conclusion, ovarian function at weaning and litter performance was higher in high body mass sows and in sows that lost the least protein in lactation, suggesting that a larger lean mass may delay the onset of a decrease in performance in sows that lose protein in lactation.     

Sow and litter response to supplemental dietary fat in lactation diets during high ambient temperatures

The objective of this experiment was to determine the impact of supplemental dietary fat on total lactation energy intake and sow and litter performance during high ambient temperatures (27 ± 3°C). Data were collected from 337 mixed-parity sows from July to September in a 2,600-sow commercial unit in Oklahoma. Diets were corn-soybean meal-based with 7.5% corn distillers dried grains with solubles and 6.0% wheat middlings and contained 3.24 g of standardized ileal digestible Lys/Mcal of ME. Animal-vegetable fat blend (A-V) was supplemented at 0, 2, 4, or 6%. Sows were balanced by parity, with 113, 109, and 115 sows representing parity 1, 2, and 3 to 7 (P3+), respectively. Feed disappearance (subset of 190 sows; 4.08, 4.18, 4.44, and 4.34 kg/d, for 0, 2, 4, and 6%, respectively; P < 0.05) and apparent caloric intake (12.83, 13.54, 14.78, and 14.89 Mcal of ME/d, respectively; P < 0.001) increased linearly with increasing dietary fat. Gain:feed (sow and litter BW gain relative to feed intake) was not affected (P = 0.56), but gain:Mcal ME declined linearly with the addition of A-V (0.16, 0.15, 0.15, and 0.14 for 0, 2, 4, and 6%, respectively; P < 0.01). Parity 1 sows (3.95 kg/d) had less (P < 0.05) feed disappearance than P2 (4.48 kg/d) and P3+ (4.34 kg/d) sows. Body weight change in P1 sows was greater (P < 0.01) than either P2 or P3+ sows (-0.32 vs. -0.07 and 0.12 kg/d), whereas backfat loss was less (P < 0.05) and loin depth gain was greater (P < 0.05) in P3+ sows compared with P1 and P2 sows. Dietary A-V improved litter ADG (P < 0.05; 1.95, 2.13, 2.07, and 2.31 kg/d for 0, 2, 4, and 6% fat, respectively) only in P3+ sows. Sows bred within 8 d after weaning (58.3, 72.0, 70.2, and 74.7% for 0, 2, 4, and 6%, respectively); conception rate (78.5, 89.5, 89.2, and 85.7%) and farrowing rate (71.4, 81.4, 85.5, and 78.6%) were improved (P < 0.01) by additional A-V, but weaning-to-breeding interval was not affected. Rectal and skin temperature and respiration rate of sows were greater (P < 0.002) when measured at wk 3 compared with wk 1 of lactation, but were not affected by A-V addition. Parity 3+ sows had lower (P < 0.05) rectal temperature than P1 and P2 sows, and respiration rate was reduced (P < 0.001) in P1 sows compared with P2 and P3+ sows. In conclusion, A-V improved feed disappearance and caloric intake, resulting in improved litter weight gain and subsequent reproductive performance of sows; however, feed and caloric efficiency were negatively affected.     

Biochemical and hematological changes in sows during estrus]

After the second and fourth parturition of piglets, ten clinically healthy sows, weaned on the second day of life, were subjected to examination two to three days before heat, during heat (defined by typical changes on the outer genitals and immobilization in the presence of a boar) and two days after insemination. During the morning hours, four hours after the last feeding, blood was taken from V. cava cranialis. Seventeen parameters were determined in whole blood and in the blood serum. In the period of oestrus, compared with the period two to three days before this period and two days after insemination, a marked increase was observed in the concentration of the serum levels of 11-hydroxycorticosteroids, iron, and in the activity of alanine aminotransferase. The activity of aspartate aminotransferase was increased in heat only in comparison with the period of the two days after insemination. The concentration of haemaglobin in whole blood was significantly increased in comparison with the period before oestrus and after insemination. Further, in the heat period -- as compared with the time before it -- a considerable drop was observed in the content of inorganic phosphorus and vitamin A. The possible mechanism of the occurrence of other changes is discussed.     

Recombinant porcine somatotropin for sows during late gestation and throughout lactation.

Two experiments were conducted to evaluate whether administration of recombinant porcine somatotropin (pST) to sows (Hampshire-Yorkshire) enhanced lactational performance. In Exp. 1, sows (n = 84) were fed a corn-soybean meal diet (17.8% CP), or a similar diet with 8% added fat, from d 108 of gestation to d 28 of lactation. Half of the sows fed each diet were injected with 6 mg/d of pST from d 108 of gestation to d 24 of lactation. Diets were fed at 2.27 kg/d from d 108 of gestation until farrowing and then were self-fed during lactation. By d 3 of lactation, litter size was standardized at 8 to 10 pigs per litter. Treating sows with pST resulted in a 10-fold increase (P less than .001) in serum somatotropin at 4 h postinjection. Serum glucose was increased (P less than .01) and serum triglycerides, creatinine, and urea N were decreased (P less than .01) by pST. During the summer, apparent heat stress occurred in pST-treated sows, resulting in 14 deaths. Most (10) of the deaths occurred just before, during, or shortly after farrowing. Fewer (P less than .08) deaths occurred when pST-treated sows were fed the diet with added fat. Sows treated with pST consumed less feed (P less than .10) and lost more backfat (P less than .10) during lactation than controls. Increasing the dietary fat did not prevent these changes. Weaning weights of pigs and milk yield of sows (estimated by deuterium oxide dilution) were not affected by pST treatment. In Exp. 2, sows (n = 42) were injected weekly with 0 or 70 mg of pST on d 3, 10, 17, and 24 of lactation. Litters were standardized by d 3 at 8 to 10 pigs, and sows were fed the same control (low fat) diet as in Exp. 1. Sows treated with pST consumed less feed and lost more weight and backfat during lactation than untreated sows. Litter size, average pig weaning weights, and milk yield were not influenced by pST treatment. These data indicate that a 6-mg daily injection of pST from 6 d prepartum to d 24 of lactation or a 70-mg weekly injection of pST from 3 d postpartum to d 24 of lactation does not increase milk production in lactating sows.