Growth of testes and testicular morphology after eight generations of selection for increased predicted weight of testes at 150 days of age in boars

Weights of testes and epididymides, body weight, and morphometric measurements of testicular tissue of 75 boars of a line selected for eight generations for predicted weight of testes at 150 d of age and 75 boars of a randomly selected control line were used to evaluate the effects of selection on testicular development at 70, 100, 130, 160, and 450 d of age (n = 15 boars per line per age). Body weights for boars of the select and control line did not differ (P < .05) and the shape of the body growth curve was similar for both lines. Boars of the select line had larger testes than control boars at each age (P < .05), but there was a significant line x age interaction. The percentage increase of the select line mean over the control mean for weight of testes was 37% at 70 d, a maximum of 120% at 100 d, and 25% at 450 d. The percentage of the testes made up of seminiferous tubules differed between lines (P < .01). Lines had similar means of approximately 28% at 70 d and 71% at 450 d, but the mean for the select line was larger between 100 and 160 d of age; the greatest difference was 11.6% (control = 43.7, select = 55.3%) at 100 d. After 70 d of age, select-line boars had a greater percentage of seminiferous tubules with lumens that contained elongated spermatids (P < .10).(ABSTRACT TRUNCATED AT 250 WORDS)     

Determination of a specific 5-HT2a antagonist (M100907) in rat and dog plasma at the femtomole/milliliter level by gas chromatography-mass spectrometry

Hypothyroidism was induced in a group of male Fischer 344 rats by administration of 0.05% propylthiouracil (PTU) in the drinking water for 12 weeks. Control rats were not treated. Plasma levels of thyroid hormones indicated that PTU treatment had produced severe thyroid hormone deficiency. In PTU-treated rats compared to control rats, levels of total T3 and total T4 were reduced 54.5% and 53.7%; while levels of free T3 and free T4 were reduced 87.1% and 96.5%. Functional hypothyroidism was demonstrated by: (i) a 49.1% decrease in hepatic plasma membrane alpha1-adrenergic receptor binding, and (ii) a 11.2-fold increase in hepatic gamma-glutamyltranspeptidase activity; relative to the expression of these parameters in control rats. Membranes were isolated from hippocampi of control, PTU-induced hypothyroid and thyroxine-replaced rats and specific adrenergic receptor binding determined by radioligand binding techniques. Hypothyroidism resulted in a shift in the balance of alpha1 and beta2 adrenergic receptor binding by evoking: an increase in alpha1-adrenergic receptor binding to 1.57-fold of control levels; and, a decrease in beta2-adrenergic receptor binding to 64% of control levels. Thyroid hormone replacement carried out in PTU-treated hypothyroid rats at 30 microg/kg s.c. per day for the last 3 days of the 12 week PTU-treatment protocol, which reversed physical and functional hypothyroidism, reversed the observed changes in hippocampal adrenergic receptor binding, indicating them to be thyroid hormone, and not PTU, -dependent. This receptor shift evoked by hypothyroidism may, in part, explain the protective effect of hypothyroidism on ischemia-induced hippocampal damage by favoring inhibitory input and limiting excitotoxic input by catecholamines.     

Influences of hypothyroidism on the taste detection performance of rats: A signal detection analysis.

Determined the influences of hypothyroidism on behavioral measures of the taste function in male and female Long-Evans rats. Experimental rats' preferences for and ability to detect NaCl, HCl, sucrose, and quinine sulfate were examined before, during, and after 9 wks of maintenance on 0.1% propylthiouracil (PTU), an agent that produces marked hypothyroidism, with similar determinations made for control animals. Despite significant decreases in PTU-treated rats' serum triiodothyronine (T?) and thyroxin (T?), there were no changes in sensitivity or responsitivity to the target tastants. However, altered preferences for NaCl, HCl, and quinine sulfate were observed for PTU-treated rats; elevated consumption of HCl and quinine sulfate was present at the end of the study when serum T? and T? had returned to near-baseline levels. The data confirm observations that PTU-induced hypothyroidism alters rats' taste preference behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of prenatal androgenization and postnatal steroid treatment on growth hormone, insulin-like growth factor I and II, insulin, thyroxine, and triidothyronine concentrations in beef heifers

A 2 x 3 factorial arrangement of treatments was used to elucidate the mechanism(s) by which prenatal androgenization improves postnatal rate and efficiency of growth and composition of gain in beef heifers. Fifteen control (C) and 15 prenatally androgenized (PA) Angus x Simmental heifers (prenatal treatment, Pretrt) received no (N), estrogen (E), or estrogen and testosterone (ET) implants postnatally (postnatal treatment, Posttrt) to evaluate whether the postpubertal growth response after prenatal androgenization could be induced in prepubertal heifers. Blood was collected from the heifers at 6 +/- 1, 9 +/- 1, and 12 +/- 1 mo of age and analyzed from serum concentrations of growth hormone (GH), IGF-I, IGF-II, insulin, thyroxine (T4), and triiodothyronine (T3). Season of the year had a greater effect on hormone concentrations than either Pretrt or Posttrt, and there were no Pretrt x Posttrt interactions. Prenatal treatment, PA, had no effect on GH; however, Posttrt E and ET increased (P < .001) GH concentrations. Prenatal treatment, PA, increased (P < .05) IGF-I concentrations, and there was a nonsignificant increase (P = .11) in IGF-I concentrations with Posttrt E and ET. Concentrations of IGF-II were unaffected by Pretrt PA; however, they were lower (P < .01) in the Posttrt E and ET groups. Insulin, T4, T3, BW, and ADG were not affected by Pretrt and Posttrt. Concentrations of GH and IGF-I were increased in heifers that received Pretrt PA and(or) Posttrt E and ET in a manner to support improved growth performance; however, BW and ADG were similar. In prepubertal beef heifers, factors in addition to increased GH and IGF-I seem to be necessary for improved growth performance.     

Effects of feeding combinations of steam-flaked grain sorghum and steam-flaked, high-moisture, or dry-rolled corn on growth performance and carcass characteristics in feedlot cattle

The objective of these two feeding trials was to determine the associative effects of feeding steam-flaked grain sorghum (SFGS) in combination with steam-flaked (SFC), dry-rolled (DRC), or high-moisture (HMC) corn on growth performance and carcass characteristics in feedlot cattle. In Trial 1, 200 yearling heifers were blocked by weight, allotted to 25 pens, and fed one of five finishing diets (77% grain, 15% corn silage, and 8% supplement on a DM basis) for an average of 137 d. The grain combinations were 100:0, 75:25, 50:50, 25:75, and 0:100 SFC:SFGS, respectively. Treatment had no effect on DMI (P > .05), but ADG, gain efficiency, and final live and hot carcass weights decreased linearly (P < .05) as the proportion of SFGS increased in the diet. Carcass backfat, quality grade, and liver abscess score were not affected (P > .05) by treatment. In Trial 2, 306 yearling steers were blocked by weight, allotted to 30 pens, and fed diets that contained 74.5% grain, 10% corn silage, 7.5% soybean meal, 4% tallow, and 4% supplement (DM basis) for an average of 139 d. The grain and grain combinations were 100% DRC, HMC, SFC, or SFGS and a 67%:33% combination of SFGS: DRC or SFGS:HMC. For steers fed diets containing a single source of grain, those fed SFC gained 7% more live weight and had a 7% higher gain efficiency (P < .05) than those fed DRC or HMC. Growth performance of steers fed SFGS was intermediate. Feeding grain combinations (67% SFGS:33% HMC or DRC) resulted in a 5 to 6% positive associative effect (P < .05) for ADG and gain efficiency. Carcass characteristics were not affected (P > .05) by treatment. We concluded that there were significant benefits (positive associative effects) when SFGS was fed in combination with DRC or HMC, but the effects were smaller when SFGS was fed in combination with SFC.     

The radiation hybrid database

The objective of this study was to evaluate morphological characteristics and testicular function of boars with different endogenous concentrations of FSH. Boars were selected at 6 mo of age on the basis of mean FSH concentrations in plasma collected at 4, 5, and 6 mo of age. Boars were classified within half-sibling families based on whether they had high concentrations of FSH (HiFSH, > 500 ng/ml, n = 9) or low concentrations (LoFSH, < 500 ng/ml, n = 7). At 14.5 mo, testes were collected, fixed, sectioned at 1 microm, and evaluated for morphological characteristics. Boars with LoFSH had larger (p < 0.01) testicular and epididymal weights than boars with HiFSH, greater (p < 0.01) daily sperm production per gram of testis, and greater total daily sperm production per boar. Testes of boars with LoFSH had a greater (p < 0.03) volume percentage of seminiferous tubules, a lesser percentage (p < 0.03) of Leydig cells, and a somewhat lesser (p = 0.06) percentage of vascular structures than testes of boars with HiFSH. Testes of boars with LoFSH had greater (p < 0.01) total tubule volume and tubule length than testes of boars with HiFSH. There were no differences (p > 0.70) in volume, diameter, or total number of Leydig cells or in total interstitial volume in testes (p > 0.41) of these two groups. Production of testosterone in vitro per paired testis and per million Leydig cells was not different (p > 0.65) between boars with HiFSH or LoFSH. Greater concentrations of FSH in blood plasma were negatively associated with development of seminiferous tubules and spermatogenic efficiency, whereas Leydig cell development was not different in boars of these two groups.     

L-ascorbyl-2-polyphosphate as a vitamin C source for segregated and conventionally weaned pigs

We conducted two experiments to evaluate the efficacy of a stable source of vitamin C for improving performance and iron status in early-weaned pigs. A preparation of L-ascorbyl-2-polyphosphate (Rovimix Stay-C 25, Roche Vitamins, Ames, IA and Bramus, NJ), which supplies 25% ascorbic acid activity in a stable form, served as the vitamin C source and was incorporated at dietary vitamin C levels of 0, 75, or 150 ppm. In Exp. 1, 72 pigs (14 +/- 2 d of age and 4.98 kg BW) were blocked based on initial BW and penned in groups of three (eight pens per treatment) in an off-site nursery for 42 d. Phase 1 lasted from d 0 to 14, Phase 2 from d 14 to 28, and Phase 3 from d 28 to 42 after weaning. Daily gain and gain:feed ratio (G/F) increased during Phase 1 (quadratic, P < .1 and P < .05, respectively), Phase 3 (linear, P < .1 and P < .01, respectively), and for the overall 42-d experiment (linear, P < .05 and P < .1, respectively) in response to increasing dietary vitamin C. At 14 d after weaning, plasma vitamin C increased (linear, P < .05) with increasing dietary vitamin C, but plasma iron, hemoglobin, and hematocrit were not influenced by dietary vitamin C. In Exp. 2, 120 pigs (20 +/- 3 d of age and 7.2 kg BW) were blocked based on initial BW and penned in groups of five (eight pens per treatment) in a conventional nursery system for 31 d. Phase 1 consisted of d 0 to 7, Phase 2 from d 7 to 17, and Phase 3 from d 17 to 31 after weaning. During the period from d 0 to 17 after weaning, ADG and G/F were improved (linear, P < .1) with increasing dietary vitamin C. At d 17 after weaning, plasma vitamin C and serum iron increased (linear, P < .05), but unbound iron-binding capacity and total iron-binding capacity decreased (linear, P < .05 and P < .1, respectively) with increasing dietary vitamin C. These results suggest that dietary vitamin C is needed during the first 42 d after weaning when pigs are weaned as early as 12 d of age and reared in an off-site nursery and during the first 17 d after weaning when pigs are weaned as early as 17 d of age and reared in a conventional nursery system. L-Ascorbyl-2-polyphosphate at a supplemental level of 75 ppm was adequate to meet the dietary vitamin C requirement of early-weaned pigs. Vitamin C supplementation with a stable product will improve performance in young pigs during the high-stress postweaning period and may be particularly beneficial to pigs weaned at a very early age.     

Re-expression of functional P-selectin molecules on the endothelial cell surface by repeated stimulation with thrombin

This study used three separate methods to evaluate sexual behavior in boars previously classified as having high (H), intermediate (INT), or low (L) levels of sexual behavior. Boars were initially evaluated for sexual behavior at 9.6 to 10.6 mo of age with a tethered female for 5 min. Boars were subsequently evaluated with a tethered female for 10 min (TF), a group of females for 10 min (FG), or continuously in a cohabitation environment for 113 h (C). When boars were evaluated with the TF procedure they mounted the female in less time (P < .01) and copulated sooner (P < .01) than when evaluated with the FG procedure. Regardless of whether the TF or FG procedure was used, L boars cumulated less time (P < .01) nosing the sides of females and took longer (P < .01) to first mount than H or INT boars. Proportion of successful matings was not different between the TF and FG procedure; however, the proportion of successful matings by H (91.7%), INT (79.2%), and L (45.8%) boars did differ (P < .001). With the C procedure, sexual behavior classification affected (P < .01) average number of successful matings (H, 4.7; INT, 2.3; and L, .33). This study indicates that sexual behavior traits expressed by a boar are similar when evaluated with a tethered female, a group of females, or a cohabitation environment.     

Low particulate type IV phosphodiesterase activity in hypothyroid rat atria

Rats were made hypothyroid by adding propylthiouracil (PTU) to their drinking water. Some of the PTU-treated rats were given thyroid hormone injections for 5 days. Both soluble and particulate cAMP-phosphodiesterase activities of adipose and ventricular tissues were increased by 25-60% in hypothyroidism. In left atria, soluble cAMP-phosphodiesterase activity was not significantly altered in hypothyroidism, while total particulate cAMP-phosphodiesterase activity was lowered by 30%. This lowering was due to diminished isoenzyme IV activity, as studied with the isoenzyme-specific inhibitors rolipram and SK&F 94836. In conclusion, the present results show decreased particulate type IV cAMP-phosphodiesterase activity in hypothyroid rat atria. This may explain the increased responsiveness to isoproterenol in hypothyroid atria.     

Questionnaire survey of proliferative enteropathy on British pig farms

Risk factors for proliferative enteropathy were investigated by means of a postal questionnaire survey of randomly selected British pig farms. Replies were received from 319 (56 per cent) of the 569 questionnaires posted, representing 1.5 per cent of the total number of pig farms in Britain. Thirty-one per cent of the farms had experienced at least one episode of proliferative enteropathy within the previous three years, usually confirmed by their veterinary surgeon. There was a strong association for the occurrence of proliferative enteropathy in herds of over 500 sows (P < 0.005) and in herds with enzootic pneumonia (P < 0.01). Outbreaks had occurred in five of the six nucleus herds surveyed, the other had only 80 sows. Outbreaks occurred in 32 of 69 herds that had obtained their replacement boars from nucleus herds (P < 0.05), suggesting that infected boars may carry the disease into distant herds. The use of either fully slatted (P < 0.05) or fully meshed floors (P < 0.01) above sunken pits in buildings used to house pigs immediately after weaning, and the use of partially (P < 0.05) or fully slatted floors (P < 0.05) in buildings used to house pigs two to six months old, were risk factors for outbreaks of proliferative enteropathy, compared with the use of straw bedding or solid floors. The destocking of entire buildings containing pigs two to four months old before the introduction of fresh pigs, was associated with a reduced risk (P < 0.05), but the destocking of selected pens rather than the whole building had no such association. The type of diet, or feeding or watering system and the types of buildings used were not identified as risk factors.     

Effects of arrival medication with tilmicosin phosphate on health and performance of newly received beef cattle

Three trials were conducted to evaluate the use of tilmicosin phosphate (Micotil) as a prophylactic medication for newly received, stressed beef cattle. In Trial 1, 57 beef calves (average initial BW = 170 kg) were shipped to the research feedlot from Tennessee and either given no antibiotic at processing or treated with Micotil at 10 mg of tilmicosin phosphate/kg of BW. During a 28-d receiving period, treatment at processing with Micotil did not affect daily gain (P < .17) or DMI (P < .22) compared to control calves. Prophylactic treatment with Micotil decreased (P < .01) the percentage of calves treated for symptoms of bovine respiratory disease from 46.4 to 0%. In Trial 2, 117 calves (average initial BW = 191 kg) were shipped from Tennessee and allotted randomly to the same two treatments as in Trial 1. All calves grazed a 24-ha pasture of irrigated winter wheat during the 28-d receiving period. Treatment of calves with Micotil at the time of arrival processing did not affect (P > .50) daily gain during the trial; however, as in Trial 1, mass treatment with Micotil decreased (P < .01) the percentage of calves treated for respiratory disease from 32.8% to 12.1%. In Trial 3, two truckloads of beef calves (183 total; average initial BW = 232 kg) shipped from Tennessee were allotted randomly to the same two treatments used in Trials 1 and 2 or to a third treatment that consisted of administration of Micotil at arrival processing if the rectal temperature of the calf was > or = 39.7 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)     

Persistence of the activity of topical ivermectin against biting lice (Bovicola bovis)

To assess the persistence of the activity of topical ivermectin against a natural challenge with biting lice (Bovicola bovis), 90 mixed-breed cattle that had been treated to remove lice, were blocked by bodyweight within sex and randomly allocated to three treatments: untreated control, doramectin at 200 micrograms/kg by subcutaneous injection, and ivermectin at 500 micrograms/kg by topical application. Forty-five pens were blocked into three groups of 15, and the blocks of pens were randomly allocated to three 14-day challenge periods starting 21, 28 and 35 days after treatment. There were five pens per treatment for each challenge period, and one B bovis-infested donor calf was introduced into each pen containing two principal calves at the start of the challenge period for that block of pens. The calves were examined thoroughly for B bovis seven, 14 and 21 days after the introduction of the donors. There were no significant differences between the control and doramectin groups for the numbers of animals infested, or the geometric mean louse counts at the final examination for any of the challenge periods. At the final examination for each challenge period, the louse counts of the cattle treated with topical ivermectin were all zero, and significantly (P < 0.05) fewer cattle treated with topical ivermectin were infested than either the controls or cattle treated with doramectin.     

Developmental expression of testis messenger ribonucleic acids in the rat following propylthiouracil-induced neonatal hypothyroidism

Propylthiouracil- (PTU) induced transient neonatal hypothyroidism increases adult rat testis weight 80-100%; this effect involves prolongation of Sertoli cell proliferation. To gain insight into developmental effects of PTU on the testis, we used Northern analysis to examine chronological expression of Sertoli cell mRNA in postnatal rat testes from rats that were untreated (controls) or were given PTU from birth to Day 25. Treated rats showed prolonged early expression of genes associated with dividing Sertoli cells such as MIS (Müllerian inhibiting substance) and c-erbA alpha (thyroid hormone receptor). Expression of several other Sertoli cell mRNAs (androgen-binding protein [ABP], clusterin, and inhibin-beta B) was delayed, as was that of hemiferrin, a spermatid-specific mRNA. Temporal expression patterns for other mRNAs (sulfated glycoprotein [SGP]-1, transferrin, and inhibin-alpha) were similar in control and treated animals. Additionally, thyroid hormone replacement in PTU-treated animals decreased MIS and c-erbA alpha mRNA expression to control levels. The altered developmental pattern of expression of a number of major Sertoli cell genes reflects a prolonged mitogenesis and delayed maturation of Sertoli cells in neonatally hypothyroid animals. Furthermore, our results suggest that thyroid hormone may directly potentiate molecular events associated with cessation of Sertoli cell proliferation and maturation during early testis development.     

Effects of an endotoxin challenge on growth performance, carcass accretion rates, and serum hormone and metabolite concentrations in control pigs and those treated with recombinant porcine somatotropin

Barrows were restrictively fed starting at 20 kg BW to determine the effects of endotoxin on growth performance of control and somatotropin-treated pigs. The following treatments were used: 1) daily i.m. vehicle injection until 55 kg BW; 2) daily i.m. injections of 100 micrograms of recombinant porcine somatotropin (pST)/kg BW, until 55 kg; 3) i.v. saline injections for 7 d consecutively starting at 60 kg BW; 4) i.v. injections of 1 microgram of bacterial lipopolysaccharide (LPS)/kg BW for 7 d starting at 60 kg BW; and 5) the combined LPS+pST treatment, with pST injections from 20 kg through the 7 d of LPS treatment. Pigs evaluated for LPS effects were fed to 60 kg anticipating a weight loss. Pigs were bled at 0800 and 1100 at 55 kg and on d 7 of LPS treatment. Rectal temperatures were taken on d 7. Treatment with pST increased ADG by 13 to 20% and improved feed:gain by 17 to 23% before LPS treatment. During the 7 d of LPS injections, ADG and feed:gain did not differ, although feed efficiency was impaired and variable. Rectal temperatures at 1100 were progressively increased: control < LPS < LPS-pST (P < .01). Protein accretion was improved 27% by pST treatment, and lipid accretion was decreased 45% before LPS. Lipid stores decreased (P < .01) after LPS treatment in the pST-treated pigs. Lipopolysaccharide treatment and(or) decreased feed intake reduced the hyperinsulinemia and hyperglycemia (P < .01) associated with pST treatment. These results indicate that LPS induced a simulated septicemia and that the effects were not negated by pST treatment. The observed hyperthermia was additive, possibly due to increased lean body mass induced by pST combined with the pyrogenic effect of LPS.     

Is adrenalectomy part of radical nephrectomy?

The spread of Classical Swine Fever (CSF) virus (strain Lorraine), originally isolated in the first CSF infected herd of the 1993-1994 Belgian epizootic, was examined in an isolation unit with three adjacent pens and 15 weaner pigs per pen. Virus was introduced through experimental inoculation of one weaner pig in the middle pen (pen 2). The experimentally inoculated pig became viraemic 4 days post-inoculation (dpi) and the pen mates at 12 (n = 9) and 14 dpi (n = 5). The first viraemia in pens 1 and 3 was observed 18 dpi. Pigs were found to be seropositive in pens 1, 2, and 3 from 24, 20, and 22 dpi onwards, respectively. The reproduction ratio (R0) for the pigs in pen 2, estimated according to the martingale method, was 81.3 (s.e. = 109.54). The rate ratio (Cox proportional hazard) of the first pigs to become viraemic in pen 3 (airborne contact plus contact via contaminated clothing and footwear with pen 2) versus pen 1 (airborne contact with pen 2 only) was 1.60 (P = 0.3342). Thus, the additional contact of contaminated clothing did not affect transmission of the CSF virus. The survivor function (Kaplan-Meier survival analysis) did not significantly differ per pen. The time from first detection of virus in plasma to death was not significantly different between pens. The mean rectal temperature of pigs in a pen increased 3 to 4 days prior to detection of virus. The proportion of seropositive pigs per pen (p) from the day the first weaner pig in a pen became viraemic (dpf) was examined as a function of time with a logistic regression model. The model parameter estimates did not differ between pens. Hence, the data from the three pens were pooled. The regression equation of the seroprevalence over time for the pooled data was p = 1/[1+e(4.65-0.39 *dpf)].     

Growth performance, intestinal microbial populations, and serum cholesterol of broilers fed diets containing Lactobacillus cultures

A study was conducted to determine the effects of adherent Lactobacillus culture on growth performance, intestinal microbial population, and serum cholesterol level of broilers. Four dietary treatments, consisting of the basal diet (control), basal diet + 0.05, 0.10, or 0.15% Lactobacillus culture (LC), were fed to 2,000 Arbor Acres broiler chicks from 1 to 42 d of age (DOA). The chicks were randomly assigned to 40 cages (50 chicks per cage, 10 cages per diet). The experimental period was 42 d. Body weights and feed to gain ratio were measured at 21 and 42 DOA. The intestinal microbial populations and serum cholesterol levels were determined at 10, 20, 30, and 40 DOA. The results showed that body weights and feed to gain ratios were improved significantly (P < 0.05) when compared to control broilers for broilers fed diets containing 0.05 or 0.10% LC, but not 0.15% LC, at 21 and 42 DOA. Coliform counts in the cecum of birds receiving 0.05% LC at 10, 20, and 30 DOA, and 0.10% at 10 and 20 DOA were significantly lower (P < 0.05) than those of the control birds. The total aerobes, total anaerobes, lactobacilli, and streptococci in the small intestines and ceca of the control birds were not significantly different from those of the treated groups. Serum cholesterol levels were significantly lower (P < 0.05) in broilers fed the three diets containing LC at 30 DOA, and in the birds fed 0.05 or 0.10% LC at 20 DOA.     

Effects of space allocation and temperature on periparturient maternal behaviors, steroid concentrations, and piglet growth rates

Preparturient sows were randomly assigned to either a farrowing crate (n = 12) or farrowing pen (n = 12) across cool and hot seasons (with or without drip cooling) to study space allocation and temperature effects on periparturient maternal behaviors, steroid concentrations, and piglet growth rates. Concentrations of estradiol-17 beta (E2 beta), progesterone (P4), and cortisol were quantified in blood collected from surgically implanted vena cava cannulas. Sows were videotaped from 2 h before to 2 h after farrowing. Similar periparturient behaviors were displayed by all sows, regardless of farrowing environment. Sows in pens had lower (P < .05) prepartum P4 concentrations from d -6 to the day preceding farrowing and a reduced (P < .05) piglet birth interval compared with sows in crates (12.95 +/- 1.35 min vs 18.31 +/- 2.21 min, respectively). Additionally, compared with multiparous sows in crates, multiparous sows in pens weaned heavier piglets (P < .05). Estradiol-17 beta concentrations were lower (P < .01) throughout lactation during hot weather for sows with or without drip cooling, averaging 9.30 pg/mL and 8.57 pg/mL, respectively, compared with 18.65 pg/mL for sows during cool weather. This decrease in E2 beta concentration in sows during hot weather was correlated with an extended (P < .05) interval from weaning to first estrus for the sows in hot weather compared to sows during cool weather. Cortisol concentrations decreased progressively during lactation and were not associated with litter weight gains or the interval between weaning and first estrus.     

Biochemical-morphological modifications of platelet membranes during pregnancy-induced hypertension

Progesterone profiles were monitored in goats housed in single (n = 9) or group (n = 14) pens during winter (JJA) and spring (SON). Normal cycles (n = 97) were < or = 30 days. Extended cycles (n = 45) were > 30 days and, except for one cycle with a persistent corpus luteum, had periovulatory periods of 10 to 20 days (n = 29) or averaging 65.1 days in length (n = 15), mostly characterised by recurrent oestrus and/or occasional transient rises in progesterone. The proportion of normal cycles occurring in winter was 87.5% (28/32) and 77.7% (42/54) for goats in single and group pens respectively, falling to 62.5% (15/24) and 37.5% (12/32) respectively in spring. The distribution of normal vs extended cycles according to season was significant (P < 0.05, single; P < 0.001 group pens). Goats housed communally experienced a greater fall in the percentage of normal cycles in spring, possibly due to increased stress associated with group feeding. Within each season, however, housing per se did not influence the distribution of normal vs extended cycles. For normal cycles, Harvey's Analysis of Variance showed that season was significantly associated with length of the periovulatory period (3.99 days (JJA) vs 5.79 days (SON); P < 0.001), oestrus detection rate (87% (JJA) vs 55% (SON); P < 0.01) and oestrus duration (1.94 days (JJA) vs 1.13 days (SON); P < 0.05). In contrast, luteal phase length was not affected by season, but was significantly associated with housing (16.93 days (single pens) vs 18.32 days (group pens); P < 0.01). The reduction in ovarian activity observed in spring may reflect a seasonal reduction in fertility, possibly linked with increasing temperature and photoperiod.     

Effect of feeding a milk replacer to early-weaned pigs on growth, body composition, and small intestinal morphology, compared with suckled littermates

Feeding of milk replacer to early-weaned pigs was evaluated in two experiments. In Exp. 1, 18 litters of pigs were either weaned conventionally (d 21), split-weaned and fed milk replacer plus starter diet (d 14 and 21), or weaned and fed milk replacer plus starter diet (d 21). Split weaning combined with feeding a milk replacer increased ADG 22% from d 14 and d 28 compared to conventional weaning (P < .05). Feeding a milk replacer plus starter diet after weaning increased ADG 30% between d 21 and 28 compared to conventional weaning (P < .01). In Experiment 2, four litters of 12 pigs each were divided at d 18 into six heavy and six light pigs and randomized across sow-suckled, milk replacer, or starter diet groups. After 1 wk, pigs fed milk replacer weighed 20% more (P < .001), contained 10% more protein (P < .01) and 17% more fat (P < .05), and had 74% longer villi in the proximal small intestine (P < .001) than suckled pigs. In contrast, pigs fed starter diet weighed 19% less (P < .001), contained 20% less protein and fat (P < .001), and had 28% shorter villi in the proximal small intestine (P < .05) than suckled pigs. Therefore, milk replacer feeding the 1st wk after weaning stimulates pig development, both locally in the small intestine and on a whole-body basis, most likely by an increased energy and nutrient intake. Suckling beyond 18 d postnatally inhibits pigs to reach maximal potential weight gain. In conclusion, milk replacer feeding might be beneficial to reach maximal pig weight gain at weaning.     

Number and function of Sertoli cells, number and yield of spermatogonia, and daily sperm production in three breeds of boar

The objective of this study was to determine the number of Sertoli cells per boar, daily sperm production, and germ cell yield per type A spermatogonium in mature Whitecross, Meishan, and West African boars. The paired parenchymal mass was greatest in the Whitecross boars and greater in Meishan than in West African boars. Daily sperm production per boar (x 10(9)) differed significantly (P < 0.05) among breeds (Whitecross: 12.5 +/- 1.5; Meishan: 6.0 +/- 0.5; West African: 2.9 +/- 0.3). Daily sperm production per boar was positively (P < 0.01) correlated with parenchymal mass (r = 0.97), number of A spermatogonia per testis (r = 0.88), and Sertoli cells per testis (r = 0.87). Daily sperm production per gram of testis was similar among breeds. Number of Sertoli cells and number of type A spermatogonia per boar were greater for the Whitecross but similar in the Meishan and West African boars. The number of Stage VII germ cells per Sertoli cell was greater (P < 0.05) in the Meishan (39.08 +/- 5.07), but similar in the Whitecross (19.91 +/- 1.62) and West African boars (15.81 +/- 2.43). The number of type A spermatogonia per testis was highly and positively (P < 0.01) correlated with number of Sertoli cells per testis (r = 0.95), and parenchymal mass (r = 0.88). There was a trend for the spermatid yield per type A spermatogonium to be greater in the Meishan boars, and this ratio was positively correlated with spermatid:Sertoli cell ratio (r = 0.62) but not with daily sperm production per boar or Sertoli cells per testis. No significant germ cell degeneration occurred during the long meiotic prophase, but the loss of progeny during postprophase of meiosis averaged 32.62% across all breeds. Germ cell degeneration was similar (P > 0.05) across breeds during spermiogenesis, and on average amounted to 8.6%. The increased number of type A spermatogonia and of Sertoli cells associated with larger testes for the Whitecross over West African or Meishan boars is sufficient to explain the higher sperm production in the Whitecross. However, the lower index of degeneration and more efficient Sertoli cell function in Meishan boars results in the daily sperm production being intermediate between that of the Whitecross and West African boars.