Effect of folic acid and glycine supplementation on embryo development and folate metabolism during early pregnancy in pigs

The present work aimed to determine if different levels of prolificacy either by parity or by genetic origin are linked to folate metabolism. Nulliparous Yorkshire-Landrace (YL) and multiparous YL, and multiparous Meishan-Landrace (ML) sows were randomly assigned to two treatments: 0 ppm or 15 ppm folic acid+0.6% glycine. Supplements were given from the estrus before mating until slaughter on d 25 of gestation. At slaughter, embryo and endometrial tissues were collected to determine concentrations of DNA, protein, and homocysteine. Allantoic fluid samples were also collected to determine concentrations of folates, vitamin B12 and amino acids. Blood samples were taken at first estrus, at mating, and on d 8, 16, and 25 of gestation to determine serum concentrations of folates, vitamin B12, and relative total folate binding capacity (TFBC). Over the entire experiment, multiparous YL sows had higher average serum concentrations of folates than nulliparous YL sows (P < 0.05) but had similar serum concentrations of relative TFBC. Concentrations of folates and relative TFBC averaged higher in ML measured over the entire experiment than in multiparous YL sows (P < 0.05). Concentrations of serum vitamin B12 were higher in multiparous YL than in ML sows or YL nulliparous sows (P < 0.05) over the entire experiment. In allantoic fluid, folates, vitamin B12, and essential amino acids contents were significantly lower in ML than in YL multiparous sows (P < 0.05). The folic acid+glycine supplement increased concentrations of serum folates, but the increase was more marked in nulliparous YL sows (nulliparous x folic acid+glycine, P < 0.05). The folic acid+glycine supplement had no effect on litter size and embryo survival, but it tended to increase embryo DNA in multiparous YL sows (P = 0.06) but not in ML and nulliparous YL sows. Homocysteine was decreased by folic acid+glycine supplement in embryos from all sows, but in endometrium, the folic acid+glycine effect was dependent on parity (nulliparous x folic acid+glycine, P < 0.05). The effects of folic acid+glycine on litter size and embryo development and survival and some aspects of folate metabolism suggest that the basal dietary content of folic acid+glycine was adequate for ML and nulliparous YL sows but not to optimize embryo development in YL multiparous sows.     

Serum folates during the reproductive cycle of sows

In a first trial, serum folates concentration was measured in 105 sows randomly distributed into seven groups of 15 animals each. Each group represented one time period of the reproductive cycle: weaning, mating, 15, 30, 60, 90 and 110 d of gestation. The average serum folates concentrations for the different groups of sows were, expressed as ng/ml +/- SE, 99.5 +/- 8.9, 68.5 +/- 9.6, 63.9 +/- 7.4, 59.5 +/- 5.7, 39.6 +/- 5.7, 45.3 +/- 5.8 and 49.1 +/- 6.3, respectively. Results showed a biphasic decrease in serum folates levels, first at mating and then at 60 d of gestation. These results indicate a possible deficiency in serum folates during mid-gestation. In a second trial, 20 sows were assigned randomly to four groups of five animals each, representing four time periods of the reproductive cycle: weaning, mating, 30 and 60 d of gestation. One intramuscular injection of 15 mg folic acid was administered to all sows and serum folates concentration was measured before the injection and at 2-d intervals during a period of 14 d after the injection. An increase in serum folates was noted in sows of all groups. The time response curves observed after the injection are presented and discussed. The decrease in folates levels observed during early and mid-gestation could be moderated by im administration of this vitamin.     

Serum zinc, iron and copper status during early gestation in sows fed a folic acid-supplemented diet

The purpose of this trial was to determine whether an addition of folic acid to a commercial diet would affect serum Zn, Fe and Cu status in sows between weaning and 30 d of gestation. At weaning, 162 sows were assigned randomly to six groups and housed in individual cages fitted on a slatted floor. There were six treatments according to a 2 X 3 factorial arrangement: two levels of supplementary folic acid (0 and 5 mg/kg of diet) and three treatments to stimulate ovulation (none, flushing and pregnant mare serum gonadotropin [PMSG] i.m. injection). Control groups were fed a commercial-type diet, and folic acid-treated groups were fed the same diet supplemented with 5 mg/kg of pteroylglutamic acid. All sows were mated twice within 7 d after weaning. Of the 162 animals originally selected, 123 sows were pregnant and used in this trial. Serum folates, Zn, Cu and Fe were measured at weaning, mating and 30 d of gestation. Serum Cu, Zn and folates increased between weaning and mating, and then decreased to 30 d of gestation. Supplementing the commercial diet with folic acid elevated serum folates between weaning and d 30 of gestation (P less than .001). Folic acid supplementation also was associated with a higher level of serum Zn at 30 d of gestation. Supplemental folic acid had no effect on the pattern of serum Cu and Fe throughout the experiment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Survival rate and development of fetuses during the first 30 days of gestation after folic acid addition to a swine diet

At weaning, 162 sows were assigned randomly to six treatments (27 in each treatment) according to a 2 X 3 factorial arrangement: two levels of supplementary folic acid (0 and 5 mg/kg of diet) and three treatments to stimulate ovulation (none, flushing and pregnant mare serum gonadotropin [PMSG] injection). All sows were mated twice within 7 d after weaning. Of the 162 animals originally selected, 123 sows were pregnant and used in this trial. The flushing treatment consisted of allowing sows ad libitum access to feed from the day after weaning through the 1st day of behavioral estrus, whereas control animals received 2.4 kg of feed daily. The hormonal treatment consisted of one i.m. injection of 1,250 IU of PMSG the day after weaning. The commercial-type diet used as the control was computed to contain .6 mg folates per kilogram. Folic acid supplementation elevated (P less than .001) serum folates between weaning and 30 d of gestation. Fetuses of sows fed the diet supplemented with folic acid had a higher (P less than .05) total protein concentration than fetuses of control sows, whereas RNA and DNA concentrations and protein:DNA ratio were not affected. The PMSG treatment elevated (P less than .05) ovulation rate, whereas the flushing or folic acid treatments had no effect on this trait. The addition of 5 mg/kg folic acid to the commercial-type diet improved (P less than .05) the survival rate of fetuses during early gestation and tended (P = .096) to increase the number of fetuses presumably living at 30 d of gestation when this treatment was associated with high ovulation rate.(ABSTRACT TRUNCATED AT 250 WORDS)     

Plasma reduced folates,reproductive performance,and conceptus development in sows in response to supplementation with oxidized and reduced sources of folic acid

The study was conducted to determine the response of sows to oxidized and reduced forms of supplemental folic acid in the diet. Gilts were mated and fed a standard corn-soybean meal diet with no supplemental folic acid. On d 105 of gestation, gilts were randomly assigned to one of four dietary treatments for the remainder of the study. Treatments were: 1) diet with no supplemental folate (control), 2) diet with 2.1 ppm (calculated) of added folate supplied by a synthetic pteroylmonoglutamate form (MG), 3) diet with 2.1 ppm (calculated) of added folate supplied by N5-formyl-5,6,7,8-tetrahydrofolic acid (THFA), or 4) a commercial bacterial cell powder source (Aj-PG) rich in reduced folates. Blood samples for high-performance liquid chromotography determination of reduced plasma folates were collected from gilts on d 105 of gestation, at weaning, at mating, and when the females were slaughtered on d 45 after mating for the second parity. There were 19, 18, 18, and 22 sows for the control, MG, THFA, and Aj-PG treatments, respectively. Supplementing folacin just before farrowing and during lactation had no effect on sow and litter performance during parity 1 (P > 0.10). Live fetuses at d 45 of gestation in Parity 2 were 10.06, 12.23, 10.87, and 11.07 for the control, MG, THFA, and Aj-PG treatments, respectively, and did not differ (P > 0.10). Fetal survival and placental size and protein content were generally unaffected by folate treatment. Concentration of reduced folates in sow plasma was 13.50, 13.58, 22.50, and 17.79 nM at weaning and 12.55, 19.29, 18.96, and 21.88 nM at mating for the control, MG, THFA, and Aj-PG treatments, respectively, with the THFA treatment elevated above the controls at weaning (P < 0.05) and the Aj-PG treatment greater than controls at mating (P < 0.05). At weaning, the reduced sources of supplemental folate (THFA and Aj-PG) were more effective in elevating plasma reduced folates than the oxidized folate supplement (MG; P < 0.05). Nonetheless, folate supplementation did not significantly improve sow reproductive performance in the subsequent parity, and there was no indication that reduced folate sources were superior to the oxidized pteroylmonoglutamate form as folate supplements for sows.     

Effects of intramuscular injections of folic acid during lactation on folates in serum and milk and performance of sows and piglets

In order to determine the effect of folic acid on serum and milk folates in lactating sows as well as on serum folates and growth rate of the piglets, sows (n = 25) received either saline or 15 mg folic acid i.m. each week from d 2 after parturition to weaning, 26 d later. Blood samples were drawn from all sows at 110 d of gestation and every week during lactation. Milk samples were taken at d 7 and 21 of lactation. Piglets were weighed and blood samples were collected weekly during lactation. Serum folates of sows increased during lactation. The rate of increase was more pronounced (P less than .0002) after folic acid injections. Milk folates concentrations decreased (P less than .0007) from d 7 to 21 of lactation but were higher (P less than .0001) in treated sows (11.8 +/- .7 ng/ml) than in control sows (7.9 +/- .4 ng/ml). Serum folates of piglets in control litters increased from 55.0 +/- 2.2 ng/ml at 2 d of age to a peak value of 86.3 +/- 3.1 ng/ml 2 wk later, and then gradually decreased. In piglets from treated dams, the time response curve was similar to that of the controls, but values were about 15% higher (P less than .01). The growth rate of piglets until 8 wk of age was not changed (P greater than .47) by folic acid injection of sows. More studies are needed to evaluate the practical importance of changes in folates status in establishing the folic acid requirements of lactating sows.     

Folic acid and reproductive performances of sows

Two-hundred nine sows were used in a 2 X 2 split-plot unbalanced design to measure the effect of folic acid against control, and flushing against a normal level of feeding, between weaning and mating on the following variables: serum folates at weaning and at 60 d of gestation, blood hemoglobin (Hb) and hematocrit (Ht) after 15 wk of gestation and reproductive performance at farrowing. Folic acid was administered im according to a schedule that maintained serum folates at approximately the same level between weaning and 60 d of gestation. The treatments had no effect on Hb or Ht after 15 wk of gestation. Average live litter size was 12.0 piglets/litter for sows receiving the folic acid and flushing treatments as compared with 10.5 for sows without any treatment; the main effect of folic acid was significant (P less than or equal to .04). Intralitter variation in birth weight and total litter weight tended to be increased by folic acid administration. Results showed that the administration of folic acid during gestation could appreciably improve the reproductive performance of sows.     

Serum folates in gestating swine after folic acid addition to diet

Folic acid was added to the diet as a simple means to increase serum folates in gestating sows. At weaning, 95 multiparous sows were randomly assigned to five treatments. Of these sows, 67 farrowed and were used for this trial. Three supplementation levels of folic acid added to a commercial diet at 3, 9 and 27 mg per kg were studied. A commercial diet without any supplementation of folic acid was used as a control treatment. A fifth treatment consisted of eight im injections of 15 mg of folic acid each, according to a predetermined schedule that was previously effective in improving the reproductive performance of sows when combined with flushing. Each sow was kept in an individual cage and received 2 kg of feed daily. Serum folates were measured at weaning, mating and on d 14, 28, 42 and 56 after mating. The time-response curve of serum folates in sows injected with folic acid was higher than that of sows fed the unsupplemented diet (P = .057). Adding folic acid to diet may be as efficient as folic acid injections to elevate serum folates when compared with sows fed the control diet. The mean supplementary level of folic acid sufficient to maintain the serum folate concentration at approximately the same levels as those observed in sows injected with folic acid was estimated to be near 4.3 mg per kg of feed.     

Effects of a parenteral supplement of folic acid and its interaction with level of feed intake on hepatic tissues and growth performance of young dairy heifers.

Forty-seven dairy heifers of approximately 10 d of age were assigned to a factorial experiment in which a supplement of folic acid (0 or 40 mg) administered weekly by i.m. injection and level of feed intake were the two factors studied. The heifers were weaned after 5 wk of experimentation. Following weaning, and until the end of the experiment, 11 wk later, they had ad libitum access to grass hay and concentrates at two different levels, ad libitum or restricted, to allow a body weight gain of 700 g/d. A supplement of folic acid (P less than .05) and ad libitum access to feed (P less than .05) increased the mean concentration of serum folates. Blood hemoglobin and packed cell volume were not affected by the level of feed intake. However, they were both increased (P less than .05) by the supplement of folic acid. Average daily gain was analyzed over three different periods: 0 to 5 wk (before weaning), 5 to 10 wk, and 10 to 16 wk. Average daily gain was increased by the supplement of folic acid during the second period (P less than .05) and by ad libitum access to feed during the last two periods (P less than .05). Ad libitum access to feed increased (P less than .05) weight of the liver, decreased the (P less than .05) concentrations of RNA and DNA, and increased (P less than .05) the ratios of protein/DNA and RNA/DNA. The supplement of folic acid decreased (P less than .05) weight of the liver and increased the ratio RNA/DNA (P less than .05). These effects of supplement of folic acid on growth performance and on hematological cells may reflect a lack of folic acid during the weeks after weaning.     

Responses of serum folates of preruminant and ruminant calves to a dietary supplement of folic acid.

The effect of dietary supplemental folic acid on serum folates of preruminant and ruminant calves was studied. In Trial 1, doses of 0, .07, .14, .28, and .56 mg of folic acid per kilogram of BW were added to the milk of preruminant calves. In Trial 2, doses of 0, .5, 1, 2, and 4 mg of folic acid per kilogram of BW were incorporated into the concentrates of ruminant heifers. In the first part of each trial, serum folates were determined in blood samples taken 0, 1, 2, 4, 8, 16 (both trials), and 32 h (Trial 2) after a single meal supplemented with folic acid. In the second part of the two trials, the supplement of folic acid was given in feed during seven consecutive days. Blood samples were taken the day before the trial and subsequently every day during 7 d. In preruminant and ruminant calves, the area under the curve and the peak of concentration of serum folates after a meal increased with the dose ingested (P less than or equal to .05, linear and quadratic effect of doses, respectively) but the amount of folic acid needed to obtain a similar response was lower for preruminant than for ruminant calves. In preruminants, the time to reach the maximal concentration was 3 to 4 h after the meal, whatever the dose ingested (P less than or equal to .05), whereas in ruminants this time decreased with the dose ingested (quadratic effect of treatment, P less than or equal to .05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of dietary L-carnitine and chromium picolinate on blood hormones and metabolites of gestating sows fed one meal per day

Gestating sows (n = 44; parity = 2.0; BW = 208 kg) were used to determine the effects of dietary L-carnitine and Cr picolinate (CrP) on daily blood hormone and metabolite profiles. Diets were formulated as a 2 x 2 factorial with L-carnitine (0 or 50 ppm) and CrP (0 or 200 ppb) and were fed from breeding through gestation, lactation, and 28 d into the subsequent gestation, at which time blood collection occurred. Sows were fed 1 meal per day during gestation (2.04 kg from breeding until d 100 and 2.95 kg from d 100 until farrowing) and ad libitum during lactation. Sows were fitted with indwelling venous catheters, and blood (plasma) was collected at feeding, then once every 15 min for the first 3 h after feeding, and at 6, 9, 15, 20, and 24 h after feeding. Postfeeding and overall insulin and connecting peptide of insulin (c-peptide) was decreased for sows fed diets with CrP or L-carnitine and was greatest for sows fed the control diet; however, sows fed both L-carnitine and CrP had an intermediate response (L-carnitine x CrP, P < 0.01). Postfeeding glucose peak was decreased (P < 0.05) in sows fed diets with L-carnitine, CrP, or both, vs. the control, and mean glucose concentration was decreased (P < 0.01) for sows fed diets with CrP. L-Carnitine decreased (P < 0.04) the NEFA concentration. Sows fed diets with CrP exhibited increased (P < 0.03) postfeeding and overall NEFA and greater (P < 0.02) fasting and overall glycerol. Overall plasma urea N was lowest for sows fed the diet with L-carnitine; however, diets containing CrP had intermediate responses compared with the control (L-carnitine x CrP, P < 0.005). Sows fed diets with L-carnitine had greater (P < 0.008) IGF-I from 3 to 24 h after feeding and tended to exhibit greater (P < 0.06) overall IGFBP-3. Sows fed the diets with CrP had greater (P < 0.05) IGFBP-3 from 2 to 20 h after feeding. No differences were observed for glucagon or triacylglycerol (P > 0.10). The changes in metabolites and metabolic hormones indicate that both L-carnitine and CrP influence energy metabolism of gestating sows; however, their effects on blood hormones and metabolites differ. Thus, the improvement in energy status from adding both L-carnitine and CrP may have an additive effect on reproductive performance of sows.     

Folic acid supplementation to diets of gestating-lactating swine over multiple parities

Crossbred gilts (n = 59) were utilized in a three-parity study to evaluate the effects of dietary additions of folic acid for reproducing swine and to ascertain if responses were dependent on the presence of a sulfonamide in the diet. The four dietary treatments were 1) control, a 14% crude protein corn-soybean meal diet with 110 ppm tylosin, 2) diet 1 plus 110 ppm sulfamethazine, 3) diet 1 plus 1 ppm folic acid and 4) diet 2 plus 1 ppm folic acid. Gilts were allotted to dietary treatment based on age, weight and ancestry within 15 d postbreeding and remained on the assigned dietary treatment continuously. Folic acid supplementation of the diet improved (P less than .05) total (11.17 vs 10.23) and live pigs born (10.79 vs 9.86) per litter; however, when litters were weaned at 28 d, the folic acid advantage was not significant (P greater than .20, 9.34 vs 9.03). No dietary effects (P greater than .10) were observed for pig birth weight or weaning weight. Number of breedings required per female farrowed tended (P less than .12) to be less for females fed folic acid-supplemented diets (1.07 vs 1.16). These results demonstrate improved sow performance through an increase in pigs born and possibly an improved conception rate when folic acid is supplemented to cornsoybean meal diets.     

Effect of feeding organic and inorganic sources of additional zinc on growth performance and zinc balance in nursery pigs

Three experiments were conducted to evaluate the effect of feeding pharmacological concentrations of zinc (Zn), from organic and inorganic sources, on growth performance, plasma and tissue Zn accumulation, and Zn excretion of nursery pigs. Blood from all pigs was collected for plasma Zn determination on d 14 in Exp. 1, d 7 and 28 in Exp. 2, and d 15 in Exp. 3. In Exp. 1, 2, and 3, 90, 100, and 15 crossbred (GenetiPorc USA, LLC, Morris, MN) pigs were weaned at 24+/-0.5, 18, and 17 d of age (6.45, 5.47, and 5.3 kg avg initial BW), respectively, and allotted to dietary treatment based on initial weight, sex, and litter. A Phase 1 nursery diet was fed as crumbles from d 0 to 14 in Exp. 1, 2, and 3, and a Phase 2 nursery diet was fed as pellets from d 15 to 28 in Exp. 1 and 2. The Phase 1 and Phase 2 basal diets were supplemented with 100 ppm Zn as ZnSO4. Both dietary phases contained the same five dietary treatments: 150 ppm additional Zn as zinc oxide (ZnO), 500 ppm added Zn as ZnO, 500 ppm added Zn as a Zn-amino acid complex (Availa-Zn 100), 500 ppm added Zn as a Zn-polysaccharide complex (SQM-Zn), and 3,000 ppm added Zn as ZnO. Overall in Exp. 1, pigs fed 500 ppm added Zn as SQM-Zn or 3,000 ppm added Zn as ZnO had greater ADG (P < 0.05) than pigs fed 150 ppm, 500 ppm added Zn as ZnO, or 500 ppm added Zn as Availa-Zn 100 (0.44 and 0.46 kg/d vs 0.35, 0.38, and 0.33 kg/d respectively). Overall in Exp. 2, pigs fed 3,000 ppm added Zn as ZnO had greater (P < 0.05) ADG and ADFI than pigs fed any other dietary treatment. On d 14 of Exp. 1 and d 28 of Exp. 2, pigs fed 3,000 ppm added Zn as ZnO had higher (P < 0.05) plasma Zn concentrations than pigs on any other treatment. In Exp. 3, fecal, urinary, and liver Zn concentrations were greatest (P < 0.05) in pigs fed 3,000 ppm added Zn as ZnO. On d 10 to 15 of Exp. 3, pigs fed 3,000 ppm added Zn as ZnO had the most negative Zn balance (P < 0.05) compared with pigs fed the other four dietary Zn treatments. In conclusion, feeding 3,000 ppm added Zn as ZnO improves nursery pig performance; however, under certain nursery conditions the use of 500 ppm added Zn as SQM-Zn may also enhance performance. The major factor affecting nutrient excretion appears to be dietary concentration, independent of source.     

Effects of a novel carbohydrate and protein source on sow performance during lactation

Ninety-one primiparous and multiparous sows and their pigs were used to evaluate the effects of a novel carbohydrate- and protein-based feed ingredient (Nutri-Pal, NP) on sow and litter performance during lactation. Nutri-Pal is a feed supplement for sows that consists of a blend of milk chocolate, brewer's yeast, whey products, and glucooligosaccharides. The dietary treatments consisted of a corn-soybean meal control and a corn-soybean meal plus 5% NP fed from d 110 of gestation to weaning. The diets were formulated to be equal in total Lys and ME. Sows were allotted to treatment based on parity, body weight, and the date of d 110 of gestation. There were 46 and 45 sows per treatment over four farrowing groups. Litters were standardized to 10 pigs and weighed within 1 d of farrowing, and all sows weaned at least 8 pigs at an average age of 21 d. Sows were weighed on d 110 of gestation, d 1 postfarrowing, and at weaning. Sows were fed three times daily during lactation. Sows were checked twice daily after weaning for signs of estrus. The weaning weight of sows fed NP was increased (P < 0.10) compared with those fed the control diet. Sows fed the control diet tended (P = 0.11) to lose more weight per day from d 110 of gestation to weaning than the sows fed NP. Otherwise, sow response variables (sow weight on d 110 of gestation and d 1 postfarrowing, d 110 of gestation to d 1 postfarrowing and lactation weight change per day, d 110 of gestation to d 1 postfarrowing, lactation, and total feed intake, days to estrus, pigs born alive or dead, and litter and average pig birth weight) were not affected (P > 0.10) by diet. There were no effects (P > 0.10) of diet on litter performance response variables (pigs weaned, litter and average pig weaning weight and gain, and survival percent). The NP feed ingredient had minor effects on sow productivity, but it did not affect litter productivity indices.     

Response of sows and litters to added dietary biotin in environmentally regulated facilities

A 3-yr study was conducted to evaluate the effects of biotin on sow longevity, reproductive performance and piglet performance to weaning utilizing 161 sows and 414 litters. Sows and gilts were fed a basal corn-soybean meal diet (without any antibiotic or chemotherapeutic compounds) during gestation and lactation containing either 0 or .55 ppm added biotin. The basal diet contained .17 ppm total dietary biotin based on microbiological assay. Results indicated sow culling rates and weight gains, number of live pigs at birth, pig weights at birth and weaning, and the interval from weaning to rebreeding were similar for both treatment groups. However, sows fed the diet with added biotin weaned more (P less than .05) pigs/litter overall and at gestation-lactation period 1 than did sows fed the basal diet without added biotin, although biotin did not increase (P greater than .10) the number of pigs weaned at gestation-lactation periods 2 through 5. The incidence of dermatitis, hair loss and soundness of feet and legs did not appear to be affected by adding biotin to the diet. Thus, the addition of .55 ppm biotin to a corn-soybean meal diet fed during gestation and lactation did not improve any of the criteria measured except number of pigs weaned overall.     

Dietary L-carnitine increases plasma leptin concentrations of gestating sows fed one meal per day

Thirty-four sows (parity=1.8; BW=206 kg) were used to determine the influence of L-carnitine and/or chromium tripicolinate on plasma leptin concentrations of gestating sows fed one meal daily. Treatments were arranged in a 2 x 2 factorial with main effects of carnitine (0 or 50 ppm) and chromium (0 or 200 ppb). Diets were fed for approximately 167 days (through one gestation, the following lactation, the interval from weaning to estrus, and 28 days into the following gestation) prior to blood collection. Leptin concentration was determined in plasma that was collected at feeding, every 15 min for the first 3h after feeding, and at 6, 9, 15, 20, and 24h after feeding. Sows fed diets containing carnitine had greater (P<0.02) overall mean plasma leptin concentrations and greater (P<0.05) leptin concentrations at 2.25, 3, 6, 15, 20, and 24h after feeding compared to sows fed either the control diet or the diet containing chromium. Leptin concentrations of sows fed diets containing carnitine also were greater (P<0.05) than control sows at 2.5 and 2.75 h postprandial and greater than (P<0.05) sows fed diets with both carnitine and chromium at 6h after feeding. Chromium had no effect (P>0.10) on plasma leptin concentration. These results suggest that dietary carnitine, but not chromium, increases circulating leptin in gestating sows fed one meal per day. These results may help to explain the improvements in reproductive function previously observed from feeding sows diets containing carnitine.     

Effects of L-carnitine fed during gestation and lactation on sow and litter performance

Multiparous sows (n = 307) were used to evaluate the effects of added dietary L-carnitine, 100 mg/d during gestation and 50 ppm during lactation, on sow and litter performance. Treatments were arranged as a 2 (gestation or lactation) x2 (with or without L-carnitine) factorial. Control sows were fed 1.81 kg/d of a gestation diet containing .65% total lysine. Treated sows were fed 1.59 kg/d of the control diet with a .23 kg/d topdressing of the control diet that provided 100 mg/d of added L-carnitine. Lactation diets were formulated to contain 1.0% total lysine with or without 50 ppm of added L-carnitine. Sows fed 100 mg/d of added L-carnitine had increased IGF-I concentration on d 60 (71.3 vs. 38.0 ng/mL, P<.01) and 90 of gestation (33.0 vs. 25.0 ng/mL, P = .04). Sows fed added L-carnitine had increased BW gain (55.3 vs 46.3 kg; P<.01) and last rib fat depth gain (2.6 vs. 1.6 mm; P = .04) during gestation. Feeding 100 mg/d of added L-carnitine in gestation increased both total litter (15.5 vs. 14.6 kg; P = .04) and pig (1.53 vs 1.49 kg; P<.01) birth weight. No differences were observed in pig birth weight variation. Added L-carnitine fed during gestation increased litter weaning weight (45.0 vs. 41.3 kg, P = .02); however, no effect of feeding L-carnitine during lactation was observed. No differences were observed in subsequent days to estrus or farrowing rate. Compared to the control diet, feeding added L-carnitine in either gestation, lactation, or both, increased (P<.05) the subsequent number of pigs born alive, but not total born. In conclusion, feeding L-carnitine throughout gestation increased sow body weight and last rib fat depth gain and increased litter weights at birth and weaning.     

Assessment of hypothalamic-pituitary-adrenal axis and sympathetic nervous system activity in pregnant sows through the measurement of glucocorticoids and catecholamines in urine

We validated the use of urine to monitor changes in the activity of both the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system (SNS) in swine. Ten pregnant sows were fitted with venous catheters 3 wk after mating. In the early (wk 6), middle (wk 9), and late (wk 14) stages of gestation, blood and urine were collected over 24 h to monitor diurnal changes in plasma cortisol, urinary cortisol, and urinary catecholamines (norepinephrine [NE] and epinephrine [EPI]). Dexamethasone suppression tests (DST) and ovine corticotropin-releasing hormone (CRH) challenge tests were also performed at each stage of gestation. All plasma and urinary values changed markedly around the clock. Diurnal variations of urinary cortisol were comparable to those in plasma, with a late nocturnal peak and a trough occurring in the evening. During the dark period, urinary catecholamines were lower than during the light period. Norepinephrine increased sharply after lights came on and peaked after meal time. Epinephrine began to rise at the end of the dark period and peaked just before meal time. Average plasma cortisol increased with the stage of gestation, due to higher levels during daylight hours. Dexamethasone at 2000 (20 microg/kg i.v.) decreased plasma cortisol at 0830 and nocturnal cortisol excretion. The magnitude of the decrease in plasma ACTH and urinary cortisol after DST was lower in late than in early and midgestation, indicating increased feedback resistance at that stage. The CRH (1 microg/kg i.v.) increased plasma and urinary cortisol. Peak levels occurred 30 min and 2 to 3 h after the injection, respectively. Catecholamines and cortisol in urine produced during the night (2000 to 0800) and the early morning (0400 to 0800 and 0800 to 0900) were highly correlated with their 24-h excretion rate. These results indicate that it is possible to monitor changes in the HPA axis and SNS activity through urinary measurements in pigs.     

Effect of dietary gestation and lactation protein levels on reproductive performance and body composition of first-litter female swine

A 2 X 3 factorial split-plot experiment was conducted to determine the effect of dietary protein on the performance and calculated body compositions of 45 first-litter sows using the D2O dilution technique at various reproductive stages. Animals were initially fed 1.82 kg daily of a 14% protein diet to 14 d post-coitum. Subsequently, two gestation protein levels (5 or 14%) were daily fed at 1.82 kg from 15 d postcoitum to parturition with three dietary lactation protein levels (5, 14 or 23%) fed from parturition to 28 d postpartum. Maternal body compositions were determined at 17, 35, 70, 85 and 105 d postcoitum and 7, 14 and 28 d postpartum using prediction equations reported previously. Gravid sows demonstrated higher maternal tissue accretion of all body chemical components from 14 to 70 d than from 70 to 105 d postcoitum. Sows fed the 5% protein gestation diet had more maternal fat but less protein accretion than those fed the 14% protein at each measurement interval. During the last trimester, those sows fed the 5% protein diet catabolized body protein reserves. Gravid sows fed the 14% protein gestation diet catabolized more maternal protein and water between 105 d postcoitum and 7 d postpartum than those fed the 5% protein diet. Litter and pig birth weights were lower and postpartum mortality higher for sows fed the 5% rather than the 14% protein gestation diet. Sows fed the 5% protein lactation diet mobilized more maternal tissue, particularly fat, between 7 and 28 d postpartum than those fed 14 or 23% protein lactation diets. These results suggest that labile maternal body protein reserves are used by gravid and nursing dams to fulfill reproductive needs and that dietary protein sequence affects the dam's performance and body composition.     

Utilization of distillers dried grains with solubles and phytase in sow lactation diets to meet the phosphorus requirement of the sow and reduce fecal phosphorus concentration

Two experiments were completed to determine the potential for using distillers dried grains with solubles (DDGS) in diets with or without phytase to provide available P, energy, and protein to highly productive lactating sows without increasing their fecal P. In Exp. 1, the dietary treatments were as follows: (1) corn and soybean meal with 5% beet pulp (BP) or (2) corn and soybean meal with 15% DDGS (DDGS). Besides containing similar amounts of fiber, diets were isonitrogenous (21% CP, 1.2% Lys) and isophosphorus (0.8% P). Sixty-one sows were allotted to dietary treatments at approximately 110 d of gestation (when they were placed in farrowing crates) based on genetics, parity, and date of farrowing. Sows were gradually transitioned to their lactation diet. On d 2 of lactation, litters were cross-fostered to achieve 11 pigs/litter. Sows and litters were weighed on d 2 and 18. Fecal grab samples were collected on d 7, 14, and 18 of lactation. Dietary treatment did not affect the number of pigs weaned (10.9 vs. 10.8) or litter weaning weight. On d 14, DDGS sows had less fecal P concentration than BP sows (28.3 vs. 32.8 mg/g; P = 0.04). Fecal Ca of sows fed DDGS decreased for d 7, 14, and 18 (55.6, 51.4, and 47.1 mg/g of DM, respectively; P = 0.05) but not for BP sows. In Exp. 2, the dietary treatments were as follows: (1) corn and soybean meal (CON), (2) CON + 500 phytase units of Natuphos/kg diet, as fed (CON + PHY), (3) corn and soybean meal with 15% DDGS and no phytase (DDGS), or (4) DDGS + 500 FTU of Natuphos/kg of diet, as fed (DDGS + PHY). Sows (n = 87) were managed as described for Exp 1. Litter BW gain (46.0, 46.3, 42.1, and 42.2 kg; P = 0.25) and sow BW loss (8.1, 7.2, 7.4, and 6.3 kg for CON, CON + PHY, DDGS, and DDGS + PHY, respectively; P = 0.97) were not affected by dietary treatment. Fecal P concentration did not differ among dietary treatments but was reduced at d 14 and 18 compared with d 7 (P = 0.001). However, fecal phytate P concentration was decreased by the addition of DDGS when DDGS and DDGS + PHY were compared with the CON sows except on d 7 (P < 0.05). Sows fed CON diet had greater fecal phytate P than sows fed DDGS, and sows fed DDGS + PHY had less fecal phytate P than sows fed DDGS with no phytase (P = 0.001). Although these experiments were only carried out for 1 lactation, these results indicate that highly productive sows can sustain lactation performance with reduced fecal phytate P when fed DDGS and phytase in lactation diets.