Dexamethasone treatment at birth enhances neonatal growth in swine

The objective of the present study was to determine if dexamethasone (Dex; a potent synthetic glucocorticoid) treatment at birth would alter postnatal growth in neonatal pigs. Forty crossbred pigs were injected i.m. with either sterile saline (Cont; n = 10 males and 10 females) or Dex (1 mg/kg; n = 10 males and 10 females) within 1 hr of birth. All pigs remained with their respective dams until 18 d of age. Body weights were recorded weekly and on d 18. On d 17, all pigs were nonsurgically fitted with an indwelling jugular catheter and placed back with the sows. On d 18, all pigs were placed in individual pens for serial blood collection. Birth weights (1.53 +/-.04 kg) did not differ between birth treatments or sex classes (P > 0.70 and 0.89, respectively). A time by treatment effect was detected (P < 0.007) for body weight such that those pigs which received Dex at birth had the greatest body weights during the 18-d period. Average daily gain was increased (P < 0.017) by 12.2% in those pigs which received Dex at birth (.286 +/-.007) as compared to the Cont pigs (.255 +/-.01 kg/d). Serum concentration of IGF-1 was influenced by both treatment (P < 0.0001) and sex class (P < 0.013). In the male pigs, Dex increased (P = 0.0041) serum concentration of IGF-1 by 47% as compared to Cont male pigs, whereas in the females, Dex increased (P < 0.011) serum concentration of IGF-1 by 34% as compared to Cont female pigs. Dex treatment reduced (P < 0.002) serum IGF-2 by 12.8%. Serum concentration of IGFBP-3 was influenced by both birth treatment (P < 0.007) and sex class (P < 0.002) such that Dex treatment increased serum IGFBP-3, and higher concentrations of IGFBP-3 were observed in boars as compared to gilts. These data suggest that the early neonatal period may be an opportune time to alter physiological factors which influence growth in swine.     

Pre- and postweaning performance of pigs injected with dexamethasone at birth

A trial was conducted to determine pre- and postweaning performance of pigs injected with dexamethasone either 1 or 24 h after birth. In Exp. 1, 225 pigs (Triumph4 x PIC Camborough 22) were assigned according to birth weight and sex to three treatments. Treatments included either saline (Control), Dex1 (2 mg/kg BW i.m. injection of dexamethasone within 1 h of birth), or Dex24 (2 mg/kg BW i.m. injection of dexamethasone within 24 h after birth). Birth weights (1.56 +/- 0.06 kg) did not differ among treatments (P > 0.10) or between sexes (P > 0.10). There was a treatment x sex interaction on BW at weaning (15 d; P < 0.05) with Dex1 and Dex24 males 10% heavier than Control males (4.77 and 4.78 vs. 4.34 kg, respectively), and no significant differences in BW among the females (P > 0.05). In Exp. 2, 180 pigs from Exp. 1 were transported to a segregated early weaning nursery facility where each sex was assigned to 10 pens per treatment (60 pens total). Pigs were fed fortified corn-soybean meal diets in a three-phase feeding program. At the end of Exp. 2 (49-d period), there was a treatment x sex interaction (P < 0.01) for BW with Dex1 and Dex24 barrows being on average 8% heavier than the Control barrows (30.1 and 29.8 vs. 27.7 kg, respectively), and no significant difference in BW (P > 0.10) among the gilts. No treatment differences in feed efficiency (gain:feed) were observed during the nursery period (P > 0.10). In Exp. 3, pigs from the nursery were moved to a finishing facility where each sex was assigned to 4 pens per treatment (24 pens total). All pigs were fed fortified corn-soybean meal diets in a four-phase feeding program with sexes fed separately. Real-time ultrasound was used to measure 10th rib backfat depth and longissimus muscle area. At the end of Exp. 3 (83-d period), there was a treatment x sex interaction (P < 0.05) for final BW with Dex1 and Dex24 barrows being on average 5.45 kg heavier than Control barrows (119.6 and 120.7 vs. 114.4 kg, respectively), and no difference (P > 0.05) in BW among the gilts. No treatment differences (P > 0.10) were observed for backfat depth, longissimus muscle area or gain:feed. These studies demonstrate that dexamethasone (2 mg/kg BW) given within 24 h of birth significantly improves both pre- and postweaning performance of barrows with no beneficial effects on gilts.     

Evaluation of exogenous glucocorticoid injection on preweaning growth performance of neonatal pigs under commercial conditions

Three commercial trials were conducted to evaluate the use of dexamethasone (Dex) and/ or isoflupredone (Predef) in improving preweaning growth performance of neonatal pigs. The objectives of the commercial trials were threefold: 1) to evaluate Predef in comparison with Dex; 2) to address the sexual dimorphic growth response observed in a previous commercial trial; and 3) to determine whether there is any benefit of providing Dex treatment to pigs being fed supplemental milk. In Exp. 1, 276 pigs (Triumph 4 x PIC Camborough 22) were assigned according to birth weight and sex to three treatments. Treatments included saline (Control), Dex (2 mg/kg BW i.m. injection of Dex), or Predef (2 mg/kg BW i.m. injection of Predef 2X) within 24 h after birth. A treatment effect was observed for BW at weaning (P < 0.001), with pigs injected with Predef being 0.51 kg lighter than Control and Dex-treated pigs. The lower BW of Predef-treated pigs at weaning were a result of a lower ADG (P < 0.001) during the preweaning period compared with Control and Dex pigs. In Exp. 2, 703 pigs (Triumph 4 x PIC Camborough 22) were assigned according to birth weight and sex to three treatments. Treatments included either an i.m. injection of saline (Control), Dexl (1 mg/kg BW of Dex), or Dex2 (2 mg/kg BW of Dex) within 24 h after birth. No treatment effects were observed for BW at weaning (P = 0.24) or ADG (P = 0.19). In Exp. 3, 342 pigs (Genetiporc) were assigned according to birth weight and sex to two treatments. Treatments included either an i.m. injection of saline or Dex (2 mg/kg BW) within 24 h after birth. All pigs were provided supplemental milk from the time of treatment until weaning age. No treatment effects were observed for BW at weaning (P = 0.13) or ADG (P = 0.11). The negative response to Predef was similar to the growth-suppressive effects observed by others using chronic glucocorticoid treatment. In contrast to our previous findings, Dex did not improve preweaning growth performance regardless of dose or supplemental milk.     

Diverse birth and rearing environment effects on pig growth and meat quality

Birth and rearing conditions were evaluated for their effects on pig growth, body composition, and pork quality using 48 barrows during the spring and summer months. Pigs were either farrowed in indoor crates or outdoor huts. At weaning, indoor-born and outdoor-born pigs were randomly allotted to indoor or outdoor treatments for growing/finishing. Body weight data were collected. Pigs were transported 5 h to a commercial processing plant, allowed 2 h of rest, and then processed as a group under commercial conditions. Boneless loins were collected from the left side of each carcass and aged for 14 d. Objective and subjective color measurements were taken on the longissimus muscle at the 10th rib on d 14 postmortem. Loin chops were evaluated for sensory attributes, shear force, and retail display features. Pigs born outdoors were heavier and had greater ADG at all growth intervals after weaning (d 28, 56, 112, and final weight, P < 0. 05) than pigs born indoors. Outdoor-born pigs had heavier carcass weights (91.2 vs 81.3+/-3.4 kg, P < 0.001), larger loineye areas (54.6 vs 49.7+/-0.2 cm , P < 0.05), and higher pork flavor intensity scores (6.5 vs 6.1+/-0.10, P < 0.01) than indoor-born pigs. Birth x rearing environment interactions were not significant for most measures. Backfat measurements at the last rib were greater (3.2 vs 2.8+/-0.05 cm, P < 0.05) for the pigs reared outdoors than for the pigs reared indoors. Pigs finished outdoors had more reddish pink color scores, lower shear force values, and lower L* values, indicating darker-colored pork, compared with pigs finished indoors (P < 0.05). Pig birth environment played a significant role in improving growth rates of outdoor-born pigs and increasing pork flavor intensity scores of loin chops from pigs born outdoors. Finishing pigs outdoors may improve pork color and tenderness but also may increase backfat thickness when they are fed conventional diets.     

Effects of age on body condition and production parameters of multiparous beef cows

Pregnancy rate, calving interval, birth weight, weaning weight, and quarterly BCS were collected for 5 consecutive years on 454 fall-calving multiparous British crossbred cattle (3 to 10 yr of age) to evaluate associations of age with BCS and production parameters. Body weight and BCS were collected pre-calving, prebreeding, at weaning, and midway through the second trimester of pregnancy (August). Body condition score was correlated with age during all seasons (P < 0.01). At calving, breeding, and in August, 3-yr-old cows had the lowest BW and BCS, whereas 8-yr-old cows had the greatest. At weaning, these values were maximal in 10-yr-old cows. Pregnancy rate was near 80% up to 9 yr of age but decreased to 57% in 10-yr-old cows. The relationship of pregnancy rate with age appears to be correlated with the BCS decrease at breeding in the older cows, supported by the fact that inclusion of BCS at breeding in the statistical model eliminated the effect of age on pregnancy rate (P = 0.42). Calving interval was longer in 3-yr-old cows compared with 4- to 9-yr-old cows (P = 0.02); however, among older cows, there was little change in the calving interval. Birth weight reached a maximum at 8 yr of age (35 +/- 0.9 kg) and a minimum in 3-yr-old cows (32 +/- 0.7 kg). Birth weights of calves born to both 3- and 4-yr-old cows were lower than for those born to 5-, 6-, 7-, or 8-yr-old cows (P < 0.05). Ten-year-old cows weaned lighter calves (205-d adjusted weaning weight) than younger dams. Furthermore, 3-yr-old cows weaned calves 9 +/- 2.1 and 14 +/- 2.4 kg lighter than 4- and 5-yr-old cows, respectively (P < 0.001). Interpretation of the age analyses of calving interval, birth weight, and weaning weight was independent of the inclusion of BCS in the model. This study documents the effects of age on calving interval, birth weight, and weaning weight that are independent of BCS.     

Influence of calving season and stocking rate on birth weight and weaning weight of Simmental-sired calves from Brahman-Hereford F1 dams.

Braham-Hereford F1 dams have been used to evaluate the influence of grazing pressure on forage attributes and animal performance at the Texas A&M University Agricultural Research Center at Overton. Data for this study were compiled from 1,909 records of Simmental-sired calves born to Braham-Hereford F1 cows from 1975 to 1990. Birth weight and weaning weight were analyzed independently to estimate the influence of year, season of birth, dam age, weaning age, and sex of calf. The effect of stocking rate as represented by levels of forage availability on weaning weights and subsequent birth weights was measured. Within the fall and winter calving seasons, lactating dams grazing at a high stocking rate produced calves with the lowest subsequent birth weights. Lactating dams assigned to creep-fed treatments had calves with the heaviest subsequent birth weights. Although dams that were less than 3.5 yr of age had calves with the lightest birth weights, there was no apparent decline in birth weight of calves from dams 12 to 17 yr old. Year, sex of calf, age of dam, stocking rate, season of birth, age at weaning, and birth weight were significant factors affecting weaning weight (P less than .01). Fall-born calves grazing cool-season annual pastures were heavier at weaning (267.6 kg) than either winter- (252.0 kg) or spring-born calves (240.9 kg). A stocking rate x season-of-birth interaction was observed for birth weight and weaning weight (P less than .05). Differences in weaning weight from low- vs high-stocked pastures were greater for fall-born calves (61.6 kg) than for winter-born calves (48.7).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of passive transfer status on preweaning growth performance in dairy goat kids

OBJECTIVE: To evaluate the effect of passive transfer status (determined from measurements of serum IgG concentration at 24 hours after parturition [sIgG-24]) on preweaning growth performance in dairy goat kids. DESIGN: Prospective observational study. ANIMALS: 20 healthy nursing dairy doe kids in a natural nonintensive breeding environment. PROCEDURES: For each kid, sIgG-24 was measured. Body weight was measured at birth and at the time of weaning 30 days (ie, 29 to 31 days) after birth; average daily gain from birth to day 30 and weight at day 30 were used as measures of preweaning growth performance. Regression analysis was used to evaluate associations between sIgG-24 and measures of preweaning growth performance. RESULTS: Mean +/- SD sIgG-24 was 31.7 +/- 10.3 mg/mL. Mean body weights at birth and weaning were 4.105 +/- 0.981 kg (9.031 +/- 2.158 lb) and 9.310 +/- 2.554 kg (20.482 +/- 5.619 lb), respectively; average daily gain was 0.174 +/- 0.072 kg/d (0.383 +/- 0.158 lb/d). No significant association was detected between sIgG-24 and birth weight. However, sIgG-24 was significantly associated with average daily gain (R(2) = 0.48) and weight at day 30 (R(2) = 0.56). Each increase in sIgG-24 of 1 mg/mL was associated with an increase in average daily gain of 0.005 kg/d (0.011 lb/d) and an increase in weight at day 30 of 0.185 kg (0.407 lb). CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that passive transfer status (determined as sIgG-24) was a significant source of variation in preweaning growth performance in dairy doe kids reared in this nonintensive breeding environment.     

Acute phase responses of pigs challenged orally with Salmonella typhimurium

This study evaluated responses of the systemic endocrine stress (cortisol) and growth (IGF-I, GH) axes, as well as those of inflammatory mediators (prostaglandin E2 [PGE2] and tumor necrosis factor alpha [TNFalpha]), to active infection with Salmonella typhimurium. Eighteen crossbred barrows were penned individually with ad libitum access to feed and water. After an acclimation period, jugular catheters were placed in all animals. Control pigs received sterile broth orally (CON, n = 7), whereas the treated pigs (S.TYP, n = 11) received 3 x 10(9) cfu of S. typhimurium orally. Plasma was collected at 6-h intervals from -48 to 120 h. Body weights, feed intake, and rectal temperatures also were monitored. Rectal temperatures were elevated in S.TYP pigs (P < .01) relative to CON pigs by 12 h, peaked at 42 h (P < .001), and remained elevated throughout the remainder of the study. Feed intake was reduced maximally in S.TYP pigs at 48 h (P < .001) and remained reduced through 120 h after the challenge. Daily body weight gain also was reduced during the 2 wk following infection (P < .001). Plasma cortisol concentrations increased (P < .05) at 18 h after the challenge in S.TYP pigs and remained elevated generally until 60 h after infection. A marked suppression of plasma IGF-I occurred in S.TYP pigs beginning at 30 h after infection (P < .001), and it remained lower through 108 h. Plasma GH was not affected consistently by treatment, nor did infection alter plasma TNFalpha and PGE2. Taken together, the results reveal that infectious processes produce profound alterations in the endocrine stress and the somatotropic axis, and this may occur in the absence of significant changes in systemic proinflammatory mediators.     

Correlated responses in reproductive and carcass traits to selection for 70-day weight in Landrace swine.

Correlated responses in reproductive and carcass traits were studied in 181 litters and 218 pigs from a line of Landrace pigs selected six generations for increased weight at 70 d of age and a contemporaneous, randomly selected control line. The reproductive and maternal traits studied included litter sizes born, born alive, and alive at 21 d and litter weight at birth and at 21 d. Carcass traits studied were carcass length, longissimus muscle area, average backfat thickness, 10th-rib backfat thickness, specific gravity, weights of closely trimmed ham, loin, and shoulder, belly weight, subjective scoring of the longissimus muscle for color and marbling, estimated percentage of muscle, and lean gain per day. Total weighted cumulative selection differential for 70-d weight was 30.2 kg. The realized heritability for 70-d weight was .13 +/- .06, and the change in 70-d weight was .65 +/- .29 kg per generation. The regression coefficient of litter size at 21 d on generation was .24 +/- .10 (P less than .10) pigs per generation. None of the other regression coefficients for the reproductive traits differed from zero. Carcass length, specific gravity, and ham weight decreased (P less than .10) -.075 +/- .036 cm, -.00054 +/- .00027, and -.102 +/- .048 kg, respectively, per generation. Color score and lean gain per day increased .046 +/- .021 points and .0032 +/- .0013 kg/d, respectively, each generation in response to the selection.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of birth weight and feeding of supplemental milk replacer to piglets during lactation on preweaning and postweaning growth performance and carcass characteristics

The effects of piglet birth weight and liquid milk replacer supplementation of piglets during lactation on growth performance to slaughter weight was evaluated in a study carried out with 32 sows (PIC C-22) and their piglets (n = 384; progeny of PIC Line 337 sires). A randomized block design with a 2 x 2 factorial arrangement of treatments was used. Treatments were birth weight (Heavy vs Light) and liquid milk replacer (Supplemented vs Unsupplemented). The study was divided into two periods. At the start of period 1 (birth to weaning), pigs were assigned to either Heavy or Light (1.8 [SD = 0.09] vs 1.3 kg [SD = 0.07] BW, respectively, P < 0.001) litters of 12 pigs and half of the litters were given ad libitum access to supplemental milk replacer from d 3 of lactation to weaning (21 +/- 0.2 d). In period 2 (weaning to 110 kg BW), a total of 308 pigs were randomly selected from within previous treatment and sex subclasses and placed in pens of four pigs. Pigs were given ad libitum access to diets that met or exceeded nutrient requirements. Pigs in heavy litters were heavier at weaning (6.6 vs 5.7 kg BW; SE = 0.14; P < 0.001) and tended to have more pigs weaned (11.4 vs 10.9 pigs/litter; SE = 0.21; P = 0.10). After weaning, pigs in the Heavy litter had greater ADG (851 vs 796 g; SE = 6.7; P < 0.001) and ADFI (1,866 vs 1,783 g; SE = 17.6; P < 0.001), similar gain:feed (0.46 vs 0.45; SE = 0.003; P > 0.05), and required seven fewer days (P < 0.001) to reach slaughter weight compared to pigs in the Light treatment. Feeding supplemental milk replacer during lactation produced heavier pigs at weaning (6.6 vs 5.7 kg BW; SE = 0.14; P < 0.001) and tended to increase the number of pigs weaned (11.4 vs 10.9 pigs/litter; SE = 0.21; P = 0.10) but had no effect (P > 0.05) on growth performance from weaning to slaughter. However, pigs fed milk replacer required three fewer days (P < 0.01) to reach 110 kg BW. Sow feed intake and BW loss during lactation were not affected (P > 0.05) by either birth weight or milk replacer treatment. In conclusion, birth weight has a substantially greater impact on pig growth performance after weaning than increasing nutrient intake during lactation.     

Serum leptin concentrations, luteinizing hormone and growth hormone secretion during feed and metabolic fuel restriction in the prepuberal gilt

Two experiments were conducted to determine 1) the effect of acute feed deprivation on leptin secretion and 2) if the effect of metabolic fuel restriction on LH and GH secretion is associated with changes in serum leptin concentrations. Experiment (EXP) I, seven crossbred prepuberal gilts, 66 +/- 1 kg body weight (BW) and 130 d of age were used. All pigs were fed ad libitum. On the day of the EXP, feed was removed from four of the pigs at 0800 (time = 0) and pigs remained without feed for 28 hr. Blood samples were collected every 10 min from zero to 4 hr = Period (P) 1, 12 to 16 hr = P 2, and 24 to 28 hr = P 3 after feed removal. At hr 28 fasted animals were presented with feed and blood samples collected for an additional 2 hr = P 4. EXP II, gilts, averaging 140 d of age (n = 15) and which had been ovariectomized, were individually penned in an environmentally controlled building and exposed to a constant ambient temperature of 22 C and 12:12 hr light: dark photoperiod. Pigs were fed daily at 0700 hr. Gilts were randomly assigned to the following treatments: saline (S, n = 7), 100 (n = 4), or 300 (n = 4) mg/kg BW of 2-deoxy-D-glucose (2DG), a competitive inhibitor of glycolysis, in saline iv. Blood samples were collected every 15 min for 2 hr before and 5 hr after treatment. Blood samples from EXP I and II were assayed for LH, GH and leptin by RIA. Selected samples were quantified for glucose, insulin and free fatty acids (FFA). In EXP I, fasting reduced (P < 0.04) leptin pulse frequency by P 3. Plasma glucose concentrations were reduced (P < 0.02) throughout the fast compared to fed animals, where as serum insulin concentrations did not decrease (P < 0.02) until P 3. Serum FFA concentrations increased (P < 0.02) by P 2 and remained elevated. Subcutaneous back fat thickness was similar among pigs. Serum IGF-I concentration decreased (P < 0.01) by P 2 in fasted animals compared to fed animals and remained lower through periods 3 and 4. Serum LH and GH concentrations were not effected by fast. Realimentation resulted in a marked increase in serum glucose (P < 0.02), insulin (P < 0.02), serum GH (P < 0.01) concentrations and leptin pulse frequency (P < 0.01). EXP II treatment did not alter serum insulin levels but increased (P < 0.01) plasma glucose concentrations in the 300 mg 2DG group. Serum leptin concentrations were 4.0 +/- 0.1, 2.8 +/- 0.2, and 4.9 +/- 0.2 ng/ml for S, 100 and 300 mg 2DG pigs respectively, prior to treatment and remained unchanged following treatment. Serum IGF-I concentrations were not effected by treatment. The 300 mg dose of 2DG increased (P < 0.0001) mean GH concentrations (2.0 +/- 0.2 ng/ml) compared to S (0.8 +/- 0.2 ng/ml) and 100 mg 2DG (0.7 +/- 0.2 ng/ml). Frequency and amplitude of GH pulses were unaffected. However, number of LH pulses/5 hr were decreased (P < 0.01) by the 300 mg dose of 2DG (1.8 +/- 0.5) compared to S (4.0 +/- 0.4) and the 100 mg dose of 2DG (4.5 +/- 0.5). Mean serum LH concentrations and amplitude of LH pulses were unaffected. These results suggest that acute effects of energy deprivation on LH and GH secretion are independent of changes in serum leptin concentrations.     

Maternal low-dose porcine somatotropin treatment in late gestation increases progeny weight at birth and weaning in sows but not in gilts

Birth weight positively predicts postnatal growth and performance in pigs and can be increased by sustained maternal porcine ST (pST) treatment from d 25 to 100 of pregnancy (term ～115 d). The objective of this study was to test whether a shorter period of maternal pST treatment in late pregnancy (d 75 to 100) could also increase birth and weaning weights of progeny under commercial conditions. Gilts (parity 0) and sows (parities 2 and 3) were not injected (controls) or injected daily with pST (gilts: 2.5 mg?d(-1), sows: 4.0 mg?d(-1), both ～13 to 14 μg?kg(-1)?d(-1)) from d 75 to 100 of pregnancy. Litter size and BW were recorded at birth and weaning, and dams were followed through the subsequent mating and pregnancy. Maternal pST injections from d 75 to 100 increased litter average progeny weight at birth (+96 g, P = 0.034) and weaning (+430 g, P = 0.038) in sows, but had no effect on progeny weight in gilts (each P > 0.5). Maternal pST treatment did not affect numbers of live-born piglets and increased numbers of stillborn piglets in sows only (+0.4 pigs/litter, P = 0.034). Maternal pST treatment did not affect subsequent reproduction of dams. Together with our previous data, these results suggest that sustained increases in maternal pST are required to increase fetal and postnatal growth in gilt progeny, but that increasing maternal pST in late pregnancy may only be an effective strategy to increase fetal and possibly postnatal growth in sow progeny.     

Effect of human growth hormone-releasing factor on bone and mineral metabolism in growing pigs

Little information is available on the effects of growth hormone (GH) and growth hormone-releasing factor (GRF and GHRH) treatment on bone metabolism in pigs. Thus, tibial bending moments and ash contents were studied in 12, 6-wk-old pigs weighing 13 +/- .2 kg. Six pigs (GRF group) were injected s.c. twice daily with 75 micrograms GRF (hGRF [1-29] NH2)/kg BW for 52 d and six remained untreated (control group, C). Average daily gain was slightly (5%; P less than .10) increased in treated pigs. At slaughter, plasma measurements related to calcium homeostasis, such as concentrations of Ca, inorganic P, and vitamin D metabolites (25-OH and 1,25-(OH)2 vitamin D3), were not changed by GRF injection. At slaughter, plasma GH levels were 3.3 times greater in treated (11.3 +/- 3 ng/ml) than in untreated pigs (3.4 +/- .5 ng/ml, P less than .02), whereas those of insulin-like growth factor I were increased by approximately 38%. No difference was observed between the two groups at slaughter in tibial weight, density, bending moment, ash relative to bone volume (29 +/- 1 vs 30 +/- 2 g/100 cm3, GRF vs C), total ash content, or ash relative to dry matter in cortical or medullary bone. Our GRF treatment did not affect bone and mineral metabolism in young, growing pigs.     

Effects of exogenous ghrelin on feed intake, weight gain, behavior, and endocrine responses in weanling pigs

The objectives were to determine relative ADG, ADFI, behavior, and endocrine responses in weaned pigs receiving exogenous ghrelin. Twenty-four barrows weaned at 18 d of age (d 0 of the experiment) were catheterized via the jugular vein, weighed, and assigned to either a ghrelin (n = 12) or saline (control; n = 12) infusion group. Initial pig BW did not differ between treatments (7.87+/-0.39 vs. 7.92+/-0.35 kg for ghrelin and control treatments, respectively). Pig BW and feed intakes were measured once daily throughout the experiment. Starting on d 1, the ghrelin pigs were intravenously infused three times daily for 5 d with 2 microg/kg BW of human ghrelin, and the control pigs were similarly infused with saline. Activity observations and blood samples were taken at -15, 0, 15, 30, 60, 90, 120, 240, and 480 min relative to the first infusion and then three times daily (0800, 1600, and 2400) for 8 d. Weight gain during the 5-d infusion period was greater by the ghrelin than by control pigs (0.57+/-0.10 vs. 0.21+/-0.13 kg, respectively; P < 0.04); however, there was no increase in feed intake. During two behavioral observation periods, more pigs in the ghrelin treatment were observed eating compared with control pigs (P < 0.05). The initial infusion of exogenous ghrelin increased serum ghrelin, GH, insulin, and cortisol concentrations (P < 0.05). Endogenous serum ghrelin increased from d 1 to 8 of the experiment in control animals (P < 0.05). Serum IGF-I initially fell in both treatment groups from d 1 to 2 (P < 0.05) but then increased from d 5 to 8 (P < 0.05). Peripheral concentrations of glucose in the ghrelin pigs were greater on d 2, 3, 7, and 8 than on d 1 (P < or = 0.05). In both treatment groups, peripheral concentrations of leptin increased from d 7 to 8, and cortisol decreased from d 1 to 5 of the experiment. These observations provide evidence that ghrelin may positively influence weight gain and concomitantly increase GH, insulin, and cortisol secretion in weaned pigs.     

Liquid diets accelerate the growth of early-weaned pigs and the effects are maintained to market weight

Piglets (n = 240, 11.0+/-0.1 d old, 3.93+/-0.05 kg) were allotted to one of four treatments in a 2 x 2 factorial arrangement to examine the effects of diet physical form and nursery environment during the first 14 d after weaning on growth to market weight. During the treatment period, pigs were housed (10 pigs/ pen) in either a conventional hot nursery (30 degrees C) or a segregated-temperature nursery (cool ambient temp. of 24 degrees C, with enclosed hot-box hovers at 32 degrees C). Pigs in each environment were fed nutritionally identical diets in either liquid or dry-pellet form for 14 d. Subsequently, all pigs were fed identical dry diets and were housed in common grower-finisher facilities (penned by sex, five pigs/pen). At the end of the treatment period (d 14), pigs fed the liquid diet were 21% heavier than pigs fed the dry pellet diet (9.22 vs 7.60 kg; P < 0.001). Similarly, gain, feed intake, and gain/feed of liquid-fed pigs were 44%, 18%, and 22% greater, respectively, than observed for pigs fed the dry pellet diet. No main effect of environment was observed (P > 0.10); however, an interaction with diet physical form occurred during the early-nursery period (P < 0.01). Pigs fed the liquid diet showed better performance in the conventional nursery, whereas pigs fed the dry pellet diet were favored in the segregated-temperature nursery. No major differences in growth performance or in ultrasound carcass measurements were detected during the growing-finishing period; however, the advantage in body weight of liquid-fed pigs gained during the first 2 wk postweaning was maintained to the end of the trial (113.9 vs 110.6 kg; P < 0.05). Pigs that were fed the early-nursery diet in liquid form reached market weight (110 kg) 3.7 d sooner than the dry-fed controls (P < 0.01). Estimates of lean gain (calculated from live ultrasound data) were unaffected, suggesting that composition of growth was not altered. Collectively, these results show that liquid feeding during early life can markedly accelerate piglet growth performance and that the growth advantage is maintained to market weight, with no evidence of compensatory gain in the dry-fed control pigs.     

Increased calf production in cattle selected for twin ovulations

The effects of increasing fetal numbers and their distribution between the left and right uterine horns on calf survival, calf BW at birth and weaning, gestation length, dystocia, and calf sex ratio were evaluated for single (n = 1,587), twin (n = 2,440), and triplet calves (n = 147) born to primiparous and multiparous females in the Twinner population at the US Meat Animal Research Center between 1994 and 2004. Cattle were distributed equally between the spring and fall breeding seasons. Fetal number and distribution in utero were determined by real-time ultrasonography at 40 to 70 d postbreeding. For cows and heifers combined, number of calves per parturition increased from 1.34 in 1994 to 1.56 in 2004. Gestation length was 6.8 d shorter (P < 0.01) for twins compared with singles (277.5 +/- 0.2 vs. 284.3 +/- 0.2 d) and 12.7 d shorter for triplets (271.6 +/- 0.8 d). Survival and BW of individual calves at birth decreased (P < 0.01) but total calf BW per dam increased (P < 0.01) as fetal number increased from single to triplet births. Twins resulting from bilateral twin ovulations had increased (P < 0.01) survival and BW at birth, a longer (P < 0.01) gestation length, and less (P < 0.01) dystocia than twins resulting from unilateral twin ovulations. Calf survival and BW at birth were 97.2 +/- 0.3% and 48.0 +/- 0.1 kg for singles, 92.0 +/- 0.4% and 39.0 +/- 0.2 kg for bilateral twins, 83.2 +/- 0.4% and 36.7 +/- 0.2 kg for unilateral twins, 73.8 +/- 1.4% and 30.6 +/- 0.7 kg for bilateral triplets, and 51.9 +/- 3.2% and 31.7 +/- 1.6 kg for unilateral triplets. Birth weight of single calves increased by 0.51 kg/d for each additional day of gestation length vs. 0.38 kg/d for individual twins. Calf BW at birth increased (P < 0.01) with age of dam from 2 to 4 yr. Twin and triplet births had a greater (P < 0.01) incidence of dystocia than single births. The ratio of male:female calves (0.52:0.48) at birth was not affected by type of birth. Postnatal calf survival was similar for all 3 types of birth. Total progeny BW at weaning for single, twin, and triplet births was 217.7 +/- 2.5, 328.3 +/- 3.2, and 378.4 +/- 15.0 kg, respectively (P < 0.01). Although most bovine females have the uterine capacity to gestate twin calves, decreased survival and BW of unilateral twins and of all triplets indicate that their growth and development may have been compromised by uterine crowding.     

Environmental effects on pig performance, meat quality, and muscle characteristics

The objective of this experiment was to determine the effect of diverse production systems on pig performance, muscle characteristics, and their relation to pork quality measures. Birth and rearing conditions were evaluated using 48 barrows during the fall/winter months. Pigs were farrowed in either indoor crates or outdoor huts. At weaning, indoor- and outdoor-born pigs were allotted randomly to treatments arranged in a 2 x 2 factorial design with two birth (indoor vs. outdoor) and rearing (indoor vs. outdoor) environments. Pigs housed indoors were on concrete-slatted flooring (1.2 m2/pig), and pigs housed outdoors were on an alfalfa pasture (212 m2/pig). Body weight data were collected. Muscle samples were removed within 1 h postmortem from the longissimus (LM) and semimembranosus (SM) muscles. Muscle samples were stained histochemically to identify type I, IIA, and IIB/X muscle fibers. Boneless loins were collected from the left side of each carcass and aged for 14 d. Objective and subjective color measurements were taken on the longissimus muscle at the 10th rib on d 14 postmortem. Loin chops were evaluated for sensory attributes, shear force, and retail display features. Pigs born outdoors were heavier and had a greater ADG at most growth intervals postweaning (d 28, 56, and 112; P < 0.05) than pigs born indoors. Pigs reared outdoors were heavier (P = 0.02) at d 140 (120.1 vs. 112.9 +/- 4.9 kg), and had higher (P = 0.01) ADG (2.2 vs. 1.9 kg/d) and gain:feed ratios (0.41 vs. 0.37) than did pigs reared indoors. Birth x rearing environment interactions were not significant (P > 0.10) for most measures. Carcass and meat quality measures did not differ (P > 0.05) among treatment groups, but loin chops from outdoor born or reared pigs had higher (P < 0.05) a* values than chops from pigs born or reared indoors. The LM muscle of pigs born outdoors had a higher (P < 0.01) percentage of type I, and a lower (P < 0.05) percentage of type IIA fibers than did pigs born indoors. Pigs reared outdoors had a higher (P < 0.01) percentage of IIA fibers and a lower (P < 0.05) percentage of IIB/X fibers than did pigs reared indoors for the LM and SM muscles. Outdoor production systems may influence growth, pork color, and muscle fiber types.     

Effects of feeder-trough space and variation in body weight within a pen of pigs on performance in a wean-to-finish production system

Two studies were carried out with the same group of pigs within a wean-to-finish system. In Study 1 (weaning to wk 8 postweaning), the effect of feeder-trough space in pens that were double-stocked on pig growth was evaluated. In Study 2 (end of wk 8 to 112 +/- 1.5 kg BW), the effect of variation in pig BW within a pen on growth was investigated. In Study 1, a randomized block design was used to compare two feeder-trough space treatments (Double [4 cm/pig] vs Control [2 cm/pig]). Pigs (n = 1,728) were randomly allocated at weaning (5.4 +/- 0.01 kg BW; 16 d of age) to mixed-sex pens (8 pens/treatment) of 108 pigs/pen on the basis of BW. Floor-space (0.30 m2/pig) and drinker allocation (13 pigs/drinker) were the same for both treatments. Two six-place (35 cm/place) feeders were positioned together in the center of each pen and were accessible from both sides. For the Double treatment, both feeders contained feed, whereas for the Control only one feeder contained feed. In Study 2, a randomized block design was used to compare three BW/variation in BW treatments: 1) Heavy BW/Low variation, 2) Light BW/Low variation, and 3) Mixed BW/Normal variation. The double-stocked pens of pigs from within previous feeder-trough space treatment were split into two groups of 54 pigs (equal sex ratio) having either high or low BW variation within pen. Pigs had free access to feed and water throughout the studies. In Study 1, doubling feeder-trough space did not affect (P > 0.05) pig growth from weaning to the end of wk 6. From wk 6 to 8, pigs on the Double treatment compared to the Control treatment had higher (P < 0.05) ADG and were heavier (P < 0.05), but had similar (P > 0.05) ADFI and gain:feed ratio. In Study 2, pen-BW treatment did not impact (P > 0.05) ADG or gain:feed ratio; however, Heavy/Low had greater (P < 0.01) ADFI than Light/Low with Mixed/Normal being intermediate for ADFI. At 112 kg BW, CV of BW within a pen was similar (P > 0.05) across treatments; however, days to market BW was greater (P < 0.001) for Light/Low than Heavy/ Low with Mixed/Normal being intermediate. In summary, increasing feeder-trough space from 2 to 4 cm per pig increased daily gain after wk 6 postweaning in double-stocked pens of pigs; however, sorting pigs on the basis of BW when splitting pens did not impact growth rate or variation in BW within a pen at market BW.     

Management program for improving sow and gilt performance by feeding dichlorvos

Treated sows were on a special management program which consisted of feeding 1,000 mg of dichlorvos to the sow each day for the last 30 days of gestation. The dichlorvos was delivered as a slow-release formulation. The late gestation treatment signigicantly (P less than 0.01) improved the productivity of the sows by improving the performance of their litters. The litters from treated sows were superior in 4 ways: (1) increased number of pigs born alive per litter (2.3%); (2) increased pig birth weights (9.6%); (3) improved survival of pigs born alive; and (4) improved growth rate to market weight. The litters from treated sows were 11.6%, 16.5%, and 12.4% heavier than control litters at birth, weaning (35 days), and market (160 days), respectively.     

Correlated responses in reproductive and carcass traits to selection for 200-day weight in Duroc swine.

Correlated responses in reproductive and carcass traits from a line of Duroc pigs selected for increased 200-d weight along with a randomly selected control line were studied in 189 litters (116 select, 73 control) and 191 pigs (106 select, 85 control), respectively. Reproductive and maternal traits studied included litter sizes born, born alive, and alive at 21 d and litter weight at birth and at 21 d. Carcass traits studied were carcass length, longissimus muscle area, average backfat thickness, 10th rib backfat thickness, specific gravity, weights of closely trimmed ham, loin, and shoulder, belly weight, subjective scoring of the longissimus muscle for color and marbling, estimated percentage of muscle and lean gain per day. Total weighted cumulative selection differential for 200-d weight was 81.7 kg. The realized heritability for 200-d weight was .18 +/- .08, and the change in 200-d weight was 2.5 +/- 1.2 kg per generation. The regression coefficient of litter size born on generation was -.29 +/- .12 (P less than .10) pigs per generation. None of the other regression coefficients for the reproductive traits differed from zero. Average backfat thickness, 10th rib backfat thickness, and belly weight increased by .093 +/- .016 cm, .122 +/- .029 cm, and .089 +/- .040 kg, respectively, per generation. Specific gravity, ham weight, shoulder weight, color score, and percentage of muscle decreased -.00086 +/- .00024, -.165 +/- .013 kg, -.104 +/- .011 kg, -.035 +/- .015 points, and -.47 +/- .12%, respectively, per generation in response to the selection.(ABSTRACT TRUNCATED AT 250 WORDS)