The objective of this experiment was to determine the association of glucocorticoids and markers for immune status in finishing beef steers and heifers with DMI, growth, and efficiency. Steers (n = ...127) and heifers (n = 109) were individually fed a finishing ration for 84 d with BW measured every 21 d. Blood samples were collected via jugular venipuncture for metabolite (glucose and lactate) and cortisol analysis and rectal grab samples of feces were collected for corticosterone analysis on d 83 of the experiment. Plasma cortisol was not correlated to DMI (r = -0.08, P > 0.05) or fractional DMI (g DMI/kg BW; r = -0.03; P > 0.05), but was negatively correlated with ADG (r = -0.17, P < 0.01) and G:F (r = -0.20; P < 0.01) and positively correlated to residual feed intake (RFI; r = 0.14, P < 0.05). Fecal corticosterone was positively correlated to fractional DMI (r = 0.15, P < 0.05) and RFI (r = 0.23, P < 0.01) and negatively correlated to G:F (r = -0.18; P < 0.01). Using a mixed model analysis, none of the metabolites or hormones were associated with DMI (P > 0.05), but fecal corticosterone was positively associated with BW-adjusted DMI in heifers only (P = 0.04). Plasma lactate (P < 0.01) was and plasma cortisol (P < 0.10) tended to be negatively associated with ADG. Plasma cortisol (P < 0.05) and fecal corticosterone tended (P < 0.10) to be negatively associated with G:F. Fecal corticosterone was positively associated with RFI in heifers (P < 0.04). In a mixed model analysis, total leukocyte count was positively associated with ADG (P < 0.04) and tended to be positively associated with G:F (P < 0.06). Amongst leukocyte subtypes, neutrophil count was positively associated with ADG in steers (P < 0.02) and monocytes were positively associated with ADG in heifers (P < 0.03). Lymphocyte counts (LY) in steers were negatively associated with DMI (P = 0.03) and fractional DMI (P < 0.03). In heifers, LY tended to be positively associated with DMI (P < 0.09) and BW-adjusted DMI (P < 0.06). Lymphocyte count was also positively associated with ADG (P < 0.01) and G:F (P = 0.05) in heifers. The association of production traits with immune status seems to be different between steers and heifers. There was a stronger relationship of cortisol than fecal corticosterone to feed efficiency measures, suggesting that an cortisol concentrations could be a better marker for feed efficiency traits than fecal corticosterone concentrations.
The goal of electric power deregulation in the United States is to lower electricity costs through market competition and greater consumer choice. This goal raises important questions: exactly what ...kinds of distributed generation (DG) should energy and environmental policy favor? What level of government is best-suited and/or most capable of governing DG? And what is the range of regulations that would most easily facilitate the competitive success of DG? In response, this article provides a comparative analysis of the electricity generation process with heat recovery created to assess the level of polluting emissions associated with a range of technologies and fuel types. Given the results of this analysis, we evaluate the governance structure responsible for regulating energy and environmental policy in the United States, and outline a regulatory approach that would ensure the use of the DG technologies and fuel sources that would be most beneficial to the environment and public health. Our analysis suggests that only the lowest emitting DG with significant waste heat recovery is even marginally competitive with combined cycle power production when air pollution issues are considered. Thus, we advocate technology-forcing in the specific form of manufacturer-based regulation, which would require, over time, the reduction of emissions from DG units at the point of manufacture as a means of ensuring greater air quality.
This study evaluated the effect of diets differing in standard ileal digestible (SID) lysine on lysine intake, growth rate, body composition and age at puberty on maternal line gilts. Crossbred Large ...White×Landrace gilts (n=641) were fed corn-soybean diets differing in SID lysine concentration (%, g SID lysine:Mcal ME); diets were not isocaloric. Gilts received three grower, finisher diet combinations: low (0.68% lysine grower, 0.52% lysine finisher), medium (0.79% lysine grower, 0.60% lysine finisher) or high (0.90% lysine grower, 0.68% lysine finisher). Grower diets were fed from 100 until 142days of age, and finisher diets were fed until they reached 220days of age. Body weight (BW), backfat thickness (BF), and loin depth (LD) were recorded every 28days. From 160–220days of age, gilts were exposed daily to vasectomized boars and observed for behavioral estrus. Gilts fed the low lysine diet had lower average daily gain and BW (P<0.05), but not fat depth:LD ratio. The percentage of gilts that displayed natural estrus by 220days of age was low but not different among dietary treatments (low 27.7%, medium 31.0% and high 37.7%, respectively; P=0.1201). Gilts fed the high and medium diets reached puberty 10 and 6days earlier, however, than gilts fed the low lysine diet (P<0.05). The rate of puberty attainment may have been less because all gilts contracted porcine epidemic diarrhea (PEDv) just as boar exposure was to begin for the first group of gilts. Results from the present study indicate that growth rate and age at puberty can be altered by ad libitum fed diets that differ in SID lysine concentration.
Onset of puberty is characterised by a marked increase in the frequency of release of gonadotrophin-releasing hormone (GnRH) and luteinising hormone (LH). The Kiss1 gene plays a critical role in ...pubertal development, and its product, kisspeptin, stimulates GnRH and LH release. In the present study, we tested the hypothesis that Kiss1 gene expression in the preoptic area (POA) and hypothalamus increases during maturation of the reproductive neuroendocrine axis in association with increased LH pulsatility. Ovariectomised, oestradiol-replaced lambs were euthanised at 25, 30 and 35 weeks of age. Blood samples were collected before euthanasia to characterise the pattern of LH release. Kiss1 mRNA was detected in coronal sections of the POA and hypothalamus and Kiss1-expressing cells were identified on the basis of silver grain density. The mean number of Kiss1-expressing cells in the POA/periventricular (PeV) areas increased from 25 to 30 weeks of age. No further increase at 35 weeks of age was observed, and the changes in Kiss1 expression in the POA/PeV were independent of changes in LH pulse frequency. The mean number of Kiss1-expressing cells in the arcuate (ARC) nucleus did not differ among age groups, although it was greater in the middle ARC of lambs exhibiting increased frequency of LH release. The density of silver grains per cell did not differ among groups in any of the areas studied. The results obtained indicate that the Kiss1 gene is activated in the POA/PeV and ARC of ewe lambs during juvenile development, and that kisspeptin neurones in the middle ARC, in particular, are involved in the acceleration of pulsatile LH release during maturation of the reproductive neuroendocrine axis in ewe lambs.
Energy demands during lactation greatly influence sow body condition and piglet performance. We hypothesized that primiparous sows or sows with reduced body condition would produce piglets with ...reduced growth and delayed sexual maturation. Eight weekly farrowing seasons were used to evaluate sow body condition (post-farrowing, PF and weaning, WN) and piglet growth from 157 dams. Body condition was measured at PF and WN using sow calipers (last rib and hip) and 10th rib ultrasound. Sows were categorized as thin, moderate, or fat by caliper (PF or WN). Individual pig weights were recorded on approximately 1, 10, WN, 45, 100, and 145 d of age. At 100 and 145 d of age, 10th-rib backfat and loin eye area were measured on 567 pigs and first estrus was monitored in 176 gilts reserved for breeding selection beginning at approximately 170 d of age. Sows had similar (P > 0.10) PF last rib caliper measurements but at WN, first parity sows had the smallest caliper measurements compared to other parities (P < 0.05). Parities 1, 2, and 3 sows had similar (P > 0.10) loin eye area at PF; however, at WN first parity sows had the smallest loin eye area (P < 0.05; 38.2 ± 0.63 cm2). Parity 1 sows had the greatest (P < 0.05) reduction of backfat and loin eye area over the lactation period (-2.9 ± 0.31 mm and -2.6 ± 0.49 cm2, respectively). At 1 d of age and WN, piglets from first parity sows weighed the least (P < 0.05) but were the heaviest (P < 0.05) at 100 and 145 d of age. Pigs from first parity litters had larger (P < 0.05) loin eye area at 100 and 145 d of age and greater backfat (P < 0.05) at 145 d of age. Fat sows at WN (last rib or hip) had the lightest (P < 0.05) piglets at 10 d of age and WN. However, at 45 d of age, piglets from fat sows (last rib or hip) were heavier (P < 0.05) than piglets from moderate and thin sows. Tenth rib backfat at 100 and 145 d of age tended (P < 0.10) to be less in pigs reared by thin sows (PF and WN hip). Tenth rib loin eye area was similar among pigs reared by fat, moderate, or thin sows. Gilts developed in litters from fourth parity sows had (P < 0.05) delayed age at puberty in contrast to gilts from first or third parity sows (200.9 ± 4.96 d vs. 189.0 ± 2.29 d and 187.5 ± 2.84 d, respectively). Although progeny body weights were typically less from first parity dams through 45 d of age, these progeny were similar or heavier at 100 and 145 d of age in contrast to progeny from other parities. Furthermore, gilt progeny from first parity dams did not have delayed pubertal attainment.
The objective of this study was to determine the effect of ad libitum feeding diets differing in standard ileal digestible (SID) lysine and ME concentrations that bracket those fed to developing ...gilts in U.S. commercial settings. Average SID lysine and ME concentrations in diets currently fed to developing gilts were obtained from a poll of the U.S. commercial swine industry. Crossbred Large White × Landrace gilts (n = 1,221), housed in groups, were randomly allotted to 6 corn-soybean diets in a 2 × 3 factorial arrangement formulated to provided 2 SID lysine and 3 ME concentrations. Gilts received grower diets formulated to provide 1.02% (control = survey average) or 0.86% (control minus 15%) SID lysine and 2.94, 3.25, or 3.57 (survey average ME ± 10%) Mcal of ME/kg from 100 d of age until approximately 90 kg BW. Then, gilts were fed finisher diet containing 0.85% (control = survey average) or 0.73% (control minus 15%) SID lysine and 2.94, 3.26, or 3.59 (control ± 10%) Mcal of ME/kg until 260 d of age. Gilts were weighed, and backfat thickness and loin muscle area were recorded at the beginning of the trial and then every 28 d. Starting at 160 d of age, gilts were exposed daily to vasectomized boars and observed for behavioral estrus. At approximately 260 d of age, gilts were slaughtered and their reproductive tract was collected. Each reproductive tract was examined to determine whether the gilt was cyclic, the stage of estrus cycle, ovulation rate, and uterine length. Data were evaluated for normality and analyzed using mixed model methods. Average age at puberty was 193 d of age with a range from 160 to 265 d. When all gilts on trial at 160 d of age were included in the analysis, 91.0% reached puberty as determine by observation of standing estrus. Differences between dietary treatments on age at puberty or measurements of the reproductive tract were not detected. Growth rates to 160 d were not limiting for attainment of puberty in response to daily boar stimulation from 160 d.
Abstract
Puberty, brought about by changes in LH pulse frequency and amplitude, is metabolically gated in the pig. How nutrition regulates LH secretion to initiate puberty in gilts is largely ...unknown. Kisspeptin (Kiss1) and neurokinin B (NKB) are neuropeptides that have been implicated in regulating LH pulsatility. The objective was to determine if changes in pulsatility of LH in gilts caused by alterations in energy balance are associated with differences in expression of Kiss1 or NKB in the medial arcuate nucleus (mARC) of the hypothalamus. Prepubertal gilts were ovariectomized and at 150 d of age fed to either gain (full-fed; n = 6) or lose (restricted; n = 6) BW for 11 d. On day 10, serial blood samples were collected every 12 min for 6 h to quantify LH pulses. On day 11, hypothalami were collected to quantify gene expression using isotopic in situ hybridization. Differences (P < 0.0001) in BW were achieved by day 5 and maintained for the remainder of the study. Mean concentrations (P < 0.01) of LH were greater in restricted gilts than in full-fed gilts (1.76 ± 0.09 ng/mL vs 1.41 ± 0.08 ng/mL, respectively), but basal concentrations of LH were not different (P = 0.59). Number of LH pulses (6.5 ± 0.5) were not different (P = 0.12), but LH pulse amplitude was greater (P < 0.001) in restricted gilts than full-fed gilts (2.32 ± 0.15 ng/mL vs 1.02 ± 0.14 ng/mL, respectively). Expression of Kiss1 mRNA was greater (P < 0.02) in the more caudal sections of the mARC, but treatment did not affect expression of Kiss1. Expression of NKB mRNA was greater (P < 0.0001) in the more caudal sections of the mARC, and expression of NKB was greater (P < 0.05) in restricted gilts when compared with full-fed gilts. The lack of treatment effect on expression of Kiss1 in the mARC or LH pulse frequency is consistent with the idea that hypothalamic expression of Kiss1 is correlated with the number of LH pulse. Although NKB is thought to be associated with LH pulse frequency, these data indicate that amplitude of LH pulses may be regulated by NKB in the gilt. AFRI (2001-67015; CAL). USDA is an equal opportunity provider and employer.
Puberty, brought about by changes in LH pulse frequency and amplitude, is metabolically gated in the pig. How nutrition regulates LH secretion to initiate puberty in gilts is largely unknown. ...Kisspeptin (Kiss1) and neurokinin B (NKB) are neuropeptides that have been implicated in regulating LH pulsatility. The objective was to determine if changes in pulsatility of LH in gilts caused by alterations in energy balance are associated with differences in expression of Kiss1 or NKB in the medial arcuate nucleus (mARC) of the hypothalamus. Prepubertal gilts were ovariectomized and at 150 d of age fed to either gain (full-fed; n = 6) or lose (restricted; n = 6) BW for 11 d. On day 10, serial blood samples were collected every 12 min for 6 h to quantify LH pulses. On day 11, hypothalami were collected to quantify gene expression using isotopic in situ hybridization. Differences (P < 0.0001) in BW were achieved by day 5 and maintained for the remainder of the study. Mean concentrations (P < 0.01) of LH were greater in restricted gilts than in full-fed gilts (1.76 ± 0.09 ng/mL vs 1.41 ± 0.08 ng/mL, respectively), but basal concentrations of LH were not different (P = 0.59). Number of LH pulses (6.5 ± 0.5) were not different (P = 0.12), but LH pulse amplitude was greater (P < 0.001) in restricted gilts than full-fed gilts (2.32 ± 0.15 ng/mL vs 1.02 ± 0.14 ng/mL, respectively). Expression of Kiss1 mRNA was greater (P < 0.02) in the more caudal sections of the mARC, but treatment did not affect expression of Kiss1. Expression of NKB mRNA was greater (P < 0.0001) in the more caudal sections of the mARC, and expression of NKB was greater (P < 0.05) in restricted gilts when compared with full-fed gilts. The lack of treatment effect on expression of Kiss1 in the mARC or LH pulse frequency is consistent with the idea that hypothalamic expression of Kiss1 is correlated with the number of LH pulse. Although NKB is thought to be associated with LH pulse frequency, these data indicate that amplitude of LH pulses may be regulated by NKB in the gilt. AFRI (2001-67015; CAL). USDA is an equal opportunity provider and employer.
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