M. J. Estienne

Concentrations of leptin in serum and milk collected from lactating sows differing in body condition

Leptin concentrations in the circulation and milk were determined in sows that differed in body condition at farrowing, and in feed consumption during lactation. Serum concentrations of leptin at farrowing and weaning were highest in sows exhibiting the greatest amount of backfat. Leptin was detected in both skim and whole milk throughout lactation, but levels were not correlated with backfat thickness or circulating leptin concentrations. This report provides the first evidence for the presence of leptin in sow milk; its function in the physiology of suckling pigs remains to be determined.

Dietary supplementation with a source of omega-3 fatty acids increases sperm number and the duration of ejaculation in boars

Development of nutritional strategies to increase the production of fertile sperm would further enhance the distribution of superior genetic material by AI. The objective was to determine the effects of a dietary source of omega-3 fatty acids in boars on semen characteristics and sexual behavior. Boars were fed daily 2.2 kg of a diet top-dressed with 0.3 kg of corn (controls; n=12) or 0.3 kg of a supplement containing 31% omega-3 fatty acids (n=12) for 16 weeks. Semen was collected weekly and for boars that received the supplement containing omega-3 fatty acids, total sperm per ejaculate averaged 84.3+/-2.3 x 10(9) (mean+/-S.E.M.) during Weeks 0-7, and increased (P=0.02) to 95.6+/-2.3 x 10(9) during Weeks 8-15. Control boars averaged 86.3+/-2.3 x 10(9) sperm per ejaculate during Weeks 0-7 and 86.4+/-2.3 x 10(9) during Weeks 8-15. Other semen characteristics were similar (P>0.1) between groups. Duration of ejaculation was affected by treatment (343.9s for controls and 388.8s for boars fed omega-3 fatty acids; S.E.M.=15.7; P=0.05). In summary, semen characteristics and sexual behavior were altered in boars fed a supplement containing omega-3 fatty acids. Boar semen is typically diluted to create AI doses containing 3 x 10(9) sperm each; therefore, use of the supplement increased the number of potential AI doses by approximately three per ejaculate after the initial 7 week supplementation period.

N-methyl-d, l-aspartate stimulates growth hormone but not luteinizing hormone secretion in the sheep.

The objective of this experiment was to determine the effects of N-methyl-d, l-aspartate (NMA) on luteinizing hormone (LH) and growth hormone (GH) secretion in castrated male sheep. Blood was sampled from Hampshire wethers every 15 min for 8 hr on day 1. At 4 and 6 hr after the initiation of the experiment, wethers were treated i.v. with NMA at a dose of 12 mg/kg body weight (n = 5) or .9% saline (n = 5). The dosage of NMA was within the range of doses that was previously demonstrated to stimulate LH secretion in monkeys. Blood samples were also collected every 15 min for 1 hr on day 2, beginning 24 hr after the first injection of NMA or saline. Treatment with NMA had no effect on mean LH concentrations, LH pulse frequency or LH pulse amplitude during the 4 hr period following the first injection on day 1. On day 2, however, mean LH concentrations were lower (p less than .01) in NMA versus saline-treated wethers. Conversely, administration of NMA evoked a dramatic increase (p less than .02) in mean GH concentrations on day 1. The mechanisms responsible for the effects of NMA described herein and whether or not these effects are relevant to the physiological control of LH and GH release in the sheep warrants further scrutiny.

Serum and milk concentrations of leptin in gilts fed a high- or low-energy diet during gestation

Concentrations of leptin in serum and milk were assessed in gilts fed diets during gestation that differed in energy level. Beginning at day 45 and continuing throughout pregnancy, gilts received either a high-energy (6882 kcal metabolizable energy (ME) per day) or low-energy (5221 kcal ME per day) diet (n = 9 per group). All gilts had ad libitum access to a standard lactation diet throughout a 21 day lactation. During gestation, gilts consuming the high-energy diet gained more body weight (P < 0.01) and backfat thickness (P = 0.03) than gilts fed the low-energy diet; however, serum concentrations of leptin remained similar between groups (P = 0.35). Within 24 h after farrowing, gilts fed the high-energy diet had greater levels of leptin in serum and milk than gilts that consumed the low-energy diet during gestation (P < 0.07); Across treatments, backfat thickness and leptin levels in serum were positively correlated (r(2) = 0.51; P = 0.03). At weaning, backfat thickness (P < 0.07), but not body weights or serum and milk levels of leptin (P > 0.1), were greater for gilts fed the high-energy, versus the low-energy, diet during gestation. Gilts that were fed the low-energy diet during gestation consumed more feed during week 2 of lactation (P = 0.06). Our results suggest that altering the level of energy in the diets of gestating swine can influence circulating and milk concentrations of leptin, as well as feed consumption, during lactation.

PGF2α facilitates the training of sexuality active boars for semen collection

Abstract The objective was to determine the effects of PGF 2α on the training of sexually active boars (i.e., boars experienced with natural mating) to mount an artificial sow for semen collection. Boars were moved to a semen collection pen twice weekly for 4 wk. After entering the pen, boars received im treatment with 10 mg PGF 2α (n = 7) or 2 mL deionized water (n = 7). Boars were classified as trained when after a successful collection, the animals mounted the artificial sow and allowed semen collection on the next scheduled day without first receiving an injection of PGF 2α or deionized water. The semen from 6 of 7 PGF 2α -treated boars and 2 of 7 control boars was collected during the first exposure to the artificial sow (P 2α -treated boars and 4 of 7 controls were successfully trained (P 2α -treated boars (.6 ± 1.0), compared to boars receiving deionized water (3.9 ± 1.0) or trained boars receiving no treatment (3.4 ± .7). Reaction time (elapsed time after entering collection pen until the start of ejaculation) was lower (P 2α -treated boars (267.4 ± 63.4 sec), compared to boars treated with deionized water (628.4 ± 98.3 sec) or boars receiving no treatment (440.4 ± 46.4 sec). In summary, use of PGF 2α facilitated the training of sexually active boars to mount an artificial sow for semen collection.

The effect of lutalyse on the training of sexually inexperienced boars for semen collection

The objective was to determine if i.m. treatments of lutalyse (PGF2alpha; dinoprost tromethamine salt) expedited the training of sexually inexperienced boars for semen collection. Lean-type, terminal-line boars (n = 40; 177.4 +/- 2.4 day of age and 112.8 +/- 2.0 kg body weight) that had not previously experienced natural mating were utilized. Boars were moved individually twice weekly for 6 weeks (total of 12 training sessions) to a semen collection room equipped with an artificial sow. Upon entering the semen collection room, boars received i.m. treatments of either deionized water (4 ml, n = 10) or lutalyse at doses of 5 mg (n = 10), 10 mg (n = 10), or 20 mg (n = 10), and subsequently received a libido score of 1-5 (1 = no interest in the artificial sow; 5 = mounting artificial sow and allowing semen collection). The percentages of boars successfully trained for semen collection during the experimental period were similar (P > 0.05) for controls (20%) and boars receiving 5 mg (30%), 10 mg (20%), or 20 mg (10%) of lutalyse. Average libido score for boars receiving 10 mg lutalyse (2.35 +/- 0.08) was greater (P < 0.05) than for controls (2.14 +/- 0.06). In summary, lutalyse increased libido scores, but did not affect the number of boars trained for semen collection.

Effects of Age on Fasting-Induced Changes in Insulin, Glucose, Urea Nitrogen, and Free Fatty Acids in Sera of Sheep

Abstract The hypothesis that prepubertal ewe lambs are metabolically different from postpuberal ewes was tested. Ovariectomized ewes (4 years of age; n = 4) and lambs (6 months of age; n = 4) were fasted for 72 hr. Serum concentrations of insulin, glucose, urea nitrogen, and free fatty acids (FFA) were measured in blood samples taken at 6-hr intervals between 30 hr before and 72 hr after feed removal. Serum concentrations of urea nitrogen and glucose were not different (P > 0.20) between age groups before fasting. Serum concentrations of insulin in ewes increased toward the end of the prefast period whereas those in lambs did not (age × time, P < 0.01). Serum concentrations of FFA in ewes tended to be lower (P < 0.07) than those in lambs prior to fasting. During fasting, concentrations of insulin decreased (P < 0.02) over time in ewes and lambs and did so in a similar manner (age × time, P > 0.70). Urea nitrogen increased (P < 0.0001) in both fasted ewes and fasted lambs in a comparable manner (age × time, P > 0.20). Concentrations of glucose during fasting were not significantly affected (P > 0.90) by age. There was a tendency (P = 0.08) for concentrations of glucose to change over time but the pattern did not appear to be related to fasting. During fasting, concentrations of FFA tended to be higher (P < 0.07) in lambs than in ewes and increased (P < 0.0001) in both groups in a similar fashion (age × time, P > 0.10). The findings herein suggest that turnover of FFA in lambs may be slightly greater than that in ewes during the fed and fasted states.

Effects of dietary supplementation with an organic source of selenium on characteristics of semen quality and in vitro fertility in boars1

Semen characteristics in boars fed organic or inorganic sources of Se were assessed in 3 experiments. Crossbred boars were randomly assigned at weaning to 1 of 3 dietary treatments: I) basal diets with no supplemental Se (control), II) basal diets with 0.3 mg/kg of supplemental Se from an organic source (Sel-Plex, Alltech Inc., Nicholasville, KY), and III) basal diets supplemented with 0.3 mg/kg of supplemental Se from sodium selenite (Premium Selenium 270, North American Nutrition Co. Inc., Lewisburg, OH). For Exp. 1, semen was collected from boars (n = 10/dietary treatment) on 5 consecutive days at 15 mo of age. Effects of treatment × day were detected for the proportions of progressively motile (P = 0.02) and rapidly moving (P = 0.03) spermatozoa, and measures of sperm velocity, including path velocity of the smoothed cell path (P = 0.05) and average velocity measured in a straight line from the beginning to the end of the track (P = 0.05). Negative effects of day of semen collection on sperm motility were least pronounced in boars fed Sel-Plex. Experiment 2 was conducted when boars were 17 mo of age, and semen was collected (n = 10 boars/dietary treatment), diluted in commercially available extenders, and stored at 18°C for 9 d. Effects of treatment × day were detected for percentages of motile (P = 0.01) and static (P = 0.01) spermatozoa, amplitude of lateral head displacement (P = 0.02), frequency with which the sperm track crossed the sperm path (P = 0.04), straightness (P = 0.01), and average size of all sperm heads (P = 0.03). In general, sperm cells from boars fed Sel-Plex were better able to maintain motility during liquid storage compared with boars fed sodium selenite. For Exp. 3, semen was collected from boars (n = 6/dietary treatment) at 23 mo of age, and spermatozoa were evaluated at d 1 and 8 after semen collection using in vitro fertilization procedures. There was a tendency for an effect (P = 0.11) of dietary treatment on fertilization rate with Sel-Plex-fed boars having the greatest value (70.7%). The results of this study suggest that there are positive effects of dietary supplementation with Sel-Plex on boar semen characteristics and that organic Se supplementation may help ameliorate the negative effects of semen storage on characteristics of sperm motility.

Type of accommodation during gestation affects growth performance and reproductive characteristics of gilt offspring.

The objective was to determine effects of the type of gestation accommodation to which dams were exposed on growth performance and age at puberty in gilt offspring. Yorkshire x Landrace gilts (n = 81; 26.9 +/- 0.8 kg of BW) were placed in pens of 3 gilts each. Each pen contained gilts farrowed exclusively by gilts exposed to 1 of 3 gestation accommodations: 1) individual crates throughout gestation; 2) group pens throughout gestation; or 3) crates for 30 d postmating and then group pens for the remainder of gestation (n = 9 pens/group). Performance during the 5-wk nursery period was similar among groups. The grow-finish period ended at a BW of 108.9 +/- 0.8 kg, and ADG (0.98 +/- 0.02 kg) was not affected (P = 0.14) by treatment. However, pig BW was affected by accommodation type x time (P = 0.04), with gilts farrowed by females housed in crates throughout gestation being heaviest during the last 4 wk. There was no effect of treatment on ADFI (2.61 +/- 0.07 kg; P = 0.54); however, G:F was enhanced (P < 0.05) in gilts farrowed by females housed in crates throughout (0.385 +/- 0.005) or for the first 30 d of gestation and then groups (0.382 +/- 0.005) compared with gilts from females kept in groups throughout gestation (0.367 +/- 0.005). Gilts from females gestated in crates throughout gestation tended (P < 0.09) to have less backfat (10.9 +/- 0.5 mm) than gilts from females gestated in groups (12.5 +/- 0.5 mm). After grow-finish, gilts were checked for estrus once daily. Mean age at puberty (171.9 +/- 4.4 d) did not differ among groups (P = 0.61); however, fewer gilts farrowed by females gestated in crates throughout gestation (P = 0.03) reached puberty by 165 d of age (13%) compared with the other 2 groups (44%). Although specific mechanisms need to be determined, we suggest that the type of gestation accommodation in which gilts are kept may affect production performance of gilt offspring, possibly by fetal programming.

Performance and physiology of pigs administered spray-dried plasma protein during the late suckling period and transported after weaning

The objective was to determine the effects of spray-dried plasma protein (SDPP), given as an oral gavage during the last 5 d of suckling, on weight gain and physiology in pigs after weaning and transportation for 5 h. Pigs were assigned to 1 of 4 treatments: 1) SDPP (9.375 g) + transportation, 2) water + transportation, 3) SDPP + no transportation, and 4) water + no transportation (n = 10 barrows and 10 gilts per treatment). Pigs received 25 mL of the SDPP (0.375 g/mL) or water twice daily. There was no effect (P = 0.55) of gavage on weaning BW. On the day of weaning, BW decreased in all groups but the magnitude was greatest in SDPP pigs that were transported (gavage × transportation × time, P = 0.03). Rectal temperatures increased in all groups but were greater after transportation than after no transportation (gavage × transportation × time, P < 0.01). Effects of transportation × time existed for several blood chemistry measures. Urea and protein concentrations increased (P < 0.01) in transported pigs only. Creatinine, chloride, and albumin increased (P < 0.01) and CO2 decreased (P < 0.01) in both transported and nontransported pigs, but the magnitudes of change were greater after transportation. Concentrations of sodium increased (P < 0.01) only in transported pigs receiving water and not in the other groups (gavage × transportation × time, P < 0.01). Concentrations of phosphorous (P < 0.01) were affected by sex × gavage × transportation × time and increased (P < 0.01) in transported, water-treated gilts but not barrows. Overall changes in concentrations of urea, creatinine, chloride, CO2, protein, albumin, sodium, and phosphorous are consistent with dehydration in transported pigs in this study and in the case of sodium (both sexes) and phosphorous (gilts only), these minerals were maintained by prior gavage with SDPP. Transported pigs receiving SDPP tended (P = 0.1) to have greater concentrations of glucose than transported pigs receiving water and had similar glucose levels to nontransported pigs receiving water, suggesting that SDPP before weaning and transportation helps to maintain concentrations. Postweaning BW was affected (P = 0.01) by gavage × time and at wk 5, pigs gavaged with SDPP tended (P = 0.1) to weigh more than pigs gavaged with water. Providing SDPP before weaning prevented transportation-induced changes in some blood components and enhanced postweaning weight gain.