Graphical approach to evaluate genetic estimates of calf survival.

Genetic variation and resemblance among relatives are fundamentals of quantitative genetics. Our purpose was to identify bulls with a bimodal pattern of inheritance in the quest for new discoveries about the inheritance of calf survival. A bimodal pattern of inheritance for calf survival was identified in sons of Holstein bulls. A bimodal pattern of inheritance indicates 2 groups of sons resulting from an allele effect, a grandsire effect, or some other common factor. Different combinations (AA, Aa, aa) of 2 alleles at a locus cause varying phenotypes to be expressed. Bulls that are heterozygous for loci affecting reproductive performance may have a bimodal pattern of inheritance if the difference in effect of the 2 alleles is large. If the bimodal pattern is caused by an allele effect, then molecular markers can be identified for use in marker-assisted selection breeding programs. Data on predicted transmitting ability for perinatal survival for the first parity of 8,678 sons of 599 sires were collected from 1984 through 1997 from the National Association of Animal Breeders calving ease database, which included 7 Midwestern states. Sixteen bulls were identified with a potential bimodal pattern of inheritance because they had 2 distinct groups of sons. The 2 groups of sons were separated by calculating the coefficient of variation for each possible combination of sons; the combination that gave the smallest coefficient of variation difference between the 2 groups was considered the correct distribution of the sons into those groups. Bulls with a bimodal distribution were analyzed to determine the distribution of the grandsons among the maternal grandsires (MGS) of the 2 groups of the bimodal distribution. The bimodal distribution may be a result of heterozygous sires or MGS that are homozygous for low or high survival. If the bimodal distribution is caused by a MGS effect, then marker-assisted selection can still be used by evaluating the MGS instead of the sires.

Porcine sperm zona binding ability as an indicator of fertility.

The escalated use of artificial insemination in swine has increased the importance of determining fertility of a semen sample before it is used. Multiple laboratory assays have been developed to assess fertilizing potential but they have yielded inconsistent results. This experiment sought to determine the relationship between in vitro competitive zona binding ability and in vivo fertility based on heterospermic inseminations and paternity testing. The zona pellucida binding ability and fertility of sperm from 15 boars was assessed by comparing sperm from one boar with sperm from other individual boars in a pairwise fashion using four ejaculates. The relationship of zona binding ability to the mean number of piglets sired per litter for each boar as well as historic fertility data (litter size and farrowing rate) was assessed. The in vitro competition assay consisted of labeling sperm from each boar of the pair with a different fluorophore and incubating an equal number of sperm from each boar in the same droplet with porcine oocytes. The competitive assay was highly effective in ranking boars by zona binding ability (R2=0.94). Paternity testing using microsatellite markers was used to determine the mean number of piglets sired per litter for each boar during heterospermic inseminations. The pairwise heterospermic insemination assay was effective in ranking boar fertility (R2=0.59). Using historical data from these boars, average litter size and farrowing rate were correlated (r=0.81, p<0.001). However, zona binding ability was not significantly correlated with historic farrowing rate data or historic average litter size. Boar sperm zona binding ability was also not correlated significantly with the mean number of piglets sired per litter following heterospermic insemination. But the number of piglets sired by each boar was related to a combination of zona binding ability, sperm motility, normal morphology, acrosomal integrity, and the presence of distal droplets (R2=0.70). These results suggest that zona binding ability is not an accurate predictor of fertilizing ability when used alone; however, when coupled with other sperm assessments, fertility may be predicted successfully.

Monoclonal antibodies specific for rat relaxin. VIII. Passive immunization with monoclonal antibodies throughout the second half of pregnancy reduces water consumption in rats.

Recent studies demonstrated that exogenous relaxin promoted drinking in nonpregnant rats. The purpose of this investigation was to determine the influence of endogenous relaxin on water consumption in pregnant rats. To that end, a monoclonal antibody specific for rat relaxin, designated MCA1, was used to passively neutralize endogenous relaxin throughout the second half of pregnancy in intact rats. Five milligrams of highly purified MCA1 were administrated iv to rats daily from days 12-22 of pregnancy. Controls received either a monoclonal antibody for fluorescein (monoclonal antibody control) or PBS (vehicle control). The amount of water consumed and both the total duration of water consumption and the total number of episodes when water was consumed were determined daily during both dark and light periods for all treatment groups. From days 13-22 of pregnancy, all three of these parameters of water consumption increased during the 10-h dark period (P < 0.01), but not during the 14-h light period. The mean daily water consumption in MCA1-treated rats was significantly less than that in controls (P < 0.05). Relaxin's effects on water consumption were limited to the 14-h light period (P < 0.01). No difference was found in daily water consumption between the MCA1-treated and control groups during the 10-h dark period. There was a tendency during the light period for both the total duration of water consumption (P = 0.06) and the total number of episodes when water was consumed (P = 0.13) to be less in MCA1-treated rats than in controls. Food consumption and body weight increased as pregnancy progressed, but no differences were found among the three treatment groups. We conclude that endogenous relaxin has effects on water consumption. It promotes water consumption during the daily light period in the second half of pregnancy in rats. Thus, relaxin may be a dipsogenic agent.

Monoclonal antibodies specific for rat relaxin. IV. Passive immunization with monoclonal antibodies during the antepartum period reduces cervical growth and extensibility, disrupts birth, and reduces pup survival in intact rats.

The purpose of this investigation was to use an approach targeted specifically on endogenous relaxin to determine the influence of antepartum (days 20-22) relaxin on cervical modifications and birth in the rat. To that end, a monoclonal antibody specific for rat relaxin, designated MCA1, was used to neutralize endogenous relaxin in intact pregnant rats. MCA1 or PBS vehicle was administered iv to intact rats daily from days 20-22 of pregnancy. Cervices were removed at 1200 h on day 22. Cervices obtained from MCA1-treated rats were less extensible than cervices obtained from PBS-treated control rats. Furthermore, wet weight, dry weight, water content, and uronate content were lower in cervices obtained from MCA1-treated rats than in cervices from PBS-treated controls. Birth and maternal behavior of MCA1-treated and PBS-treated control rats were observed continuously from 2100 h on day 22 until day 2 postpartum (d2PP). MCA1-treated rats exhibited significantly prolonged durations of litter delivery as well as reduced incidences of live pups on d2PP compared with controls. There were lower incidences of normal maternal behavior observed at birth and on d1PP with MCA1-treated rats than with control rats. In addition, little or no milk was observed in the abdomen of most live pups of MCA1-treated rats on d2PP, whereas abundant milk was observed in the abdomen of all live pups of control rats. The mean live pup weight on d2PP was lower in the litters of MCA1-treated rats than in control litters. The present study indicates that in the rat endogenous relaxin is needed during the antepartum period for normal cervical growth and extensibility, normal litter delivery, and high postpartum pup survival. This work supports the hypothesis that the influence of endogenous relaxin on birth is attributable, at least in part, to its effects on the cervix.

Influence of litter size on antepartum serum relaxin and progesterone immunoactivity levels and on birth in the rat.

In the rat, the antepartum elevation of serum relaxin levels consists of two phases separated by a 24-h interval. The second phase, which occurs between 36 and 24 h before birth, is temporally closely associated with functional luteolysis. Relaxin levels then decline throughout the last approximately 24 h of pregnancy. We have postulated that the two phases in the antepartum elevation of serum relaxin levels may be indicative of an increasingly effective endogenous circadian luteolytic process. There is limited evidence that both luteolysis and birth are delayed in rats with small litters. The present study investigated in detail the relationship between litter size and the timing of both functional luteolysis and birth in rats. The number of conceptuses (C) in Sprague-Dawley-derived rats was surgically adjusted on day 8 of pregnancy (day 8) so that rats bore one, two, three, five, or a full complement (FC) of eight or more C. Rats were maintained under a photoperiod regimen of 14 h of light and 10 h of darkness (lights on from 2100-1100 h) beginning on day 8 and observed for birth at 10-min intervals from 2100 h on day 22. Serum levels of both relaxin and progesterone were determined in blood samples obtained at 4-h intervals from 2400 h on day 19 until birth. Ninety-five percent of the rats that had five or more C gave birth during the light phase on day 23, which was designated the normal birth interval. However, only 20% of the rats with three C or less, gave birth during the normal birth interval, and 47% gave birth about 24 h later during the light phase on day 24, which was designated the late birth interval. The 24-h delay in birth of rats with small litters which delivered during the late birth interval appears to be attributable to a delay in functional luteolysis; the antepartum decline in serum relaxin and progesterone levels occurred about 24 h later in these rats than in rats that delivered during the normal birth interval. It is concluded that the C may be associated with the luteolytic process and thereby influence the time of birth in rats. Additionally, the results of this study are consistent with our hypothesis that there is an endogenous circadian luteolytic process in rats during the antepartum period.

Hormonal control of the cervix in pregnant gilts. I. Changes in the physical properties of the cervix correlate temporally with elevated serum levels of estrogen and relaxin.

The time course of changes in the physical properties of both the uterine and vaginal portions of the cervix were studied during the last two thirds (days 40 to approximately 115) of pregnancy in the gilt. To obtain insight concerning the hormonal control of these physical changes, serum levels of relaxin, estrone, 17 beta-estradiol, and progesterone were also determined. Throughout midpregnancy, the extensibility (softness), lumen diameter, and wet weight of the uterine portion of the cervix were less than those of the vaginal portion of the cervix. After day 80, marked and sustained increases in these three physical parameters occurred in the uterine portion of the cervix whereas slight (extensibility) or moderate (lumen diameter and wet weight) increases occurred in the vaginal portion of the cervix. By day 110, extensibility, lumen diameter, and wet weight of the uterine portion of the cervix were similar to those of the vaginal portion of the cervix. Because the uterine portion of the cervix has a relatively firm consistency and small lumen throughout most of pregnancy, we conclude that it probably plays a more important role than the vaginal portion of the cervix in protecting the uterus and its contents during pregnancy. The marked changes in the physical properties of the uterine portion of the cervix are temporally correlated with elevated serum estrogen levels (days 80-100) or estrogen and relaxin levels (day 100 to term). We conclude that estrogen or, more likely, estrogen and relaxin in combination may promote the modifications in the physical properties of the cervix that occur during the last 35 days of gestation.

Evidence that systemic relaxin promotes moderate water consumption during late pregnancy in rats.

The protein hormone relaxin is secreted by the ovaries throughtout the second half of the 23 day pregnancy in the rat. We recently reported that neutralization of endogenous relaxin with monoclonal antibodies for rat relaxin decreases water consumption during the daily light period during the second half of pregnancy in rats. The apparent effects of relaxin on water consumption, however, were extremely modest. One explanation for the failure to observe a greater relaxin-dependent effect on water consumption is failure of the monoclonal antibody for rat relaxin to neutralize all circulating relaxin. A second explanation is that circulating relaxin has only slight effects on water consumption. This investigation was conducted with an experimental model in which circulating relaxin was removed in order to re-examine the effects of relaxin on water consumption during the daily light period in late pregnancy in rats. On day 9 (D9) of pregnancy, before the presence of relaxin (R) in the circulation, primiparious pregnant rats were ovariectomized (O) or sham ovariectomized (C). Throughout the remainder of pregnancy, rats were treated with combinations of either progesterone (P) and estrogen (E, group OPE) or progesterone, estrogen and porcine relaxin (group OPER) in doses that restore physiological parameters to values similar to those that occur during the second half of pregnancy in intact rats. Progesterone and estrogen were administered by Silastic tubing implants and porcine relaxin was administered via miniature osmotic pump. Sham-ovariectomized animals received either the hormone vehicles (group SC) or no implants (group IC). Water consumption was measured daily from D4 to D20 at both 0700 and 2100 h which was when the lights went on and off respectively. Water consumption increased as pregnancy continued from D10 to D20 during the daily 10 h dark periods (P < 0.01), but not during the 14 h light periods for all four groups. Daily water consumed by rats in group OPE was significantly lower (P < 0.05) than that consumed by shamovariectomized rats from D17 to D20 and lower than that consumed by rats in group OPER on D20. During the dark period there was no difference in water consumption among groups. During the light period, however, group OPE consumed significantly less water (P < 0.05) than group C from D18 to D22. Moreover, there was a consistent tendency (P < 0.13) for the water consumption to be greater in rats in group OPER than in those in the relaxin-deficient group OPE during the daily light period from D11 to D20 of pregnancy. We conclude that the increase in water consumption that occurs during the daily dark periods during the second half of pregnancy is not attributable to circulating relaxin. Circulating relaxin promotes only modest increases in water consumption during the daily light periods during late pregnancy in the rat.

Evaluation of breed as a risk factor for atresia coli in cattle.

Systematic review of published cases and a hospital-based case-control study were completed to evaluate breed as a risk factor for atresia coli in cattle. Systematic review of 37 published studies indicated that atresia coli has been diagnosed in 10 cattle breeds and 12 countries, with the marked preponderance of cases occurring in Holstein-Friesian calves (485/514 cases, 94%). Epidemiologic analysis based on 28,373 cattle < 2 mo of age admitted to North American veterinary schools between 1964 and 1993 identified 291 cases of atresia coli in 13 breeds, with the marked preponderance of cases occurring in Holstein-Friesian calves (228/291, 78%). Holstein-Friesian cattle were at significantly greater risk for the condition than all other dairy cattle breeds (crude odds ratio 4.55, P < 0.0001) and all other cattle breeds (crude odds ratio 7.12, P < 0.0001), whereas there was no difference in the odds ratio between dairy cattle (not Holstein-Friesian) and beef cattle (crude odds ratio 1.68, P = 0.11). Atresia coli probably occurs secondary to vascular insufficiency of the developing colon. Holstein-Friesian cattle may be genetically predisposed to atresia coli, possibly because their developing colon grows at a faster rate and/or to a greater extent than that in other cattle breeds. Early or vigorous palpation per rectum of the amniotic vesicle appears to increase the risk of atresia coli in a genetically predisposed fetus, probably through palpation-induced damage to the developing colonic vasculature.

Investigation of breeding strategies to increase the probability that German shepherd dog and Labrador retriever dog guides would attain optimum size.

An optimum-sized dog guide weighs 18 to 32 kg and measures 53 to 64 cm in height at the withers when mature body size is attained. Effects of selection index with and without restrictions, independent trait selection, directional selection, stabilizing selection, and negative assortative mating were modeled using data from German shepherd dogs and Labrador retrievers raised by the Seeing Eye, Inc., Morristown, NJ from 1979 to 1997. The selection goals were to decrease mature weight and mature height in German shepherd dogs and to decrease mature weight and increase mature height in Labrador retrievers. Mature weights were recorded for 1,333 German shepherd dog offspring and their 69 dams and 17 sires, and 1,081 Labrador retriever offspring and their 51 dams and 13 sires. Mature heights also were recorded for offspring and parents, including 871 German shepherd dogs from 70 dams and 15 sires, and 793 Labrador retrievers from 40 dams and 13 sires. Selecting on mature weight alone produced the highest aggregate genetic-economic gain for German shepherd dogs compared with the selection indices with and without restrictions, generating a 2.10-kg decrease in mature weight and a correlated 0.36-cm decrease in mature height. In Labrador retrievers, selecting for mature height alone produced the highest aggregate genetic-economic gain but caused an increase in mature weight. Weighting the two traits equally but in the opposite direction without restrictions was the only index that produced the desired effect of decreasing mature weight and increasing mature height in Labrador retrievers. Response to selection for one generation of directional selection for a single trait included a 0.50-kg decrease in mature weight for German shepherd dogs, a 0.59-kg decrease in mature weight for Labrador retrievers, a 0.18-cm decrease in mature height for German shepherd dogs, and a 0.91-cm increase in mature height for Labrador retrievers. Increasing the percentage of dogs attaining optimum size may decrease the cost of production for the Seeing Eye, Inc., because fewer dogs would need to be raised and trained to provide assistance to the same number of blind individuals.

Deficiency of uridine monophosphate synthase in Holstein cattle: inheritance and body measurements.

Blood samples and body measurements were obtained from daughters of seven Holstein bulls previously shown to have a partial deficiency of uridine monophosphate (UMP) synthase and presumed to be heterozygous for the condition. Erythrocyte UMP synthase for 85 daughters showed a bimodal distribution with 42 having half the normal activity of 43 others. Furthermore, each bull had 50% of his daughters represented in each group, a finding fully consistent with the heterozygous designation of these bulls. Because UMP synthase is needed for pyrimidine biosynthesis and hence DNA and RNA metabolism, it was hypothesized that a partial deficiency could result in slower growth and smaller size for affected animals. Body measurements, as estimates of growth and size, included body length, wither height, hip height, hip width, rump length, pin width and taped body weight. Although measurements varied by age, differences between normal and heterozygous females were not found. One-half the normal activity of UMP synthase in cattle was adequate for near normal growth. Additionally, herd life was not significantly affected in heterozygous females.

Breed and sex differences in growth curves for two breeds of dog guides.

A desirable dog guide weighs 18 to 32 kg as an adult. Male and female German shepherd dogs and male and female Labrador retrievers were weighed between birth and 18 mo of age, with at least one weight recorded after 290 d of age. Growth curves were constructed from 10,484 observations on 880 dogs using the Gompertz function in the form Wt = W(max)exp(-e[-(t-c)/b]), where Wt is weight at time t, Wmax is mature body weight, b is proportional to duration of growth, c is age at point of inflection, and t is age in days. Estimates for mature body weight were 2.4 +/- .3 kg higher for Labrador retrievers than for German shepherd dogs and 4.7 +/- .2 kg higher for males than for females. Male Labrador retrievers were closest to the upper limit for desirable weight, with an average estimated mature weight of 31.4 +/- .3 kg. Duration of growth, 4b + c, was not different between the breeds; however, the estimate for males was 8 +/- 5d longer than for females. Female Labrador retrievers had the shortest estimate for growth of 319 +/- 6 d. The estimate for age at the point of inflection was 3.6 +/- 1.2 d greater for males than for females, but not different between breeds. A better understanding of growth curves for dog guides may aid in estimating mature weight at a young age, thus allowing earlier breeding and training decisions to be made and increasing genetic change per year.

The relationship of porcine sperm zona-binding ability to fertility.

Several laboratory assays have been designed to assess the fertility potential of a semen sample before insemination, but none have been consistent and accurate predictors of fertility. To determine whether zona-binding ability may be a useful fertility predictor, we validated and used an in vitro competitive assay to measure the ability of porcine sperm to bind to the zona pellucida. The zona-binding ability of sperm from 11 boars that exhibited a broad range in average litter size and farrowing rate was determined. Sperm from each boar were compared directly with sperm from eight other boars in a systematic, pairwise fashion. Sperm from two semen samples were labeled with fluorophores at concentrations that did not affect motility or zona-binding ability. An equal number of labeled sperm from each boar was coincubated with homologous oocytes. Least squares means from analysis of variance were used to rank boars based on zona-binding ability. The competitive assay was effective in establishing a ranking of the boars (R2 = 0.62). Furthermore, there was a correlation between zona-binding ability and fertility when estimated by average litter size (r = 0.64, P < 0.05) but not when estimated by farrowing rate (r = -0.28). The explanation for this difference was that litter size and farrowing rate were poorly correlated (r = 0.14). In conclusion, a competitive zona-binding assay distinguished boars that sired either small or large litters. Competitive zona-binding ability may be useful for identifying boars with reduced fertility that produce smaller litters following insemination.

Estimated genetic parameters for growth traits of German shepherd dog and Labrador retriever dog guides.

A desirable dog guide weighs 18 to 32 kg and measures 53 to 64 cm in height at the withers as an adult. Heritabilities and genetic correlations were estimated for birth weight, 42-d weight, mature weight, and mature height for 2,334 German shepherd dogs and 2,028 Labrador retrievers raised by the Seeing Eye, Inc., Morristown, NJ, from 1979 to 1997. Data included 5,006 observations for German shepherd dogs from 113 dams and 33 sires and 4,123 observations for Labrador retrievers from 89 dams and 29 sires. A mixed effects model was considered with sex and birth year as fixed effects. Random effects were animal, maternal, and litter incorporating all pedigree information available. A derivative-free REML method was used to estimate parameters. The maternal component was higher than the additive genetic component for birth weight. Heritability of mature weight was estimated as 0.57 +/- 0.07 for German shepherd dogs and 0.44 +/- 0.07 for Labrador retrievers. Mature height heritability was estimated as 0.35 +/- 0.08 for German shepherd dogs and 0.46 +/- 0.08 for Labrador retrievers. Selection for lighter dogs at maturity is predicted to decrease the average mature height, and selection for taller dogs at maturity is predicted to increase the average mature weight. The estimated genetic parameters will aid in the development of strategies to increase the probability of breeding dogs for optimum mature size.

Effects of double stocking and weighing frequency on pig performance in wean-to-finish production systems.

Two studies were carried out in different wean-to-finish barns to determine the effects of double stocking on pig growth performance. In Study 1, pigs (n = 1,560) were used in a randomized complete block design with a 2 x 2 factorial arrangement of treatments: initial stocking treatment (Single [52 pigs/pen] vs Double [104 pigs/pen] stocked for 10 wk after weaning) and weighing frequency (High [12 times during the study] vs Low [3 times]) on pig performance from weaning (5.9+/-0.01 kg BW; 17 d of age) to harvest (114+/-0.67 kg BW). Floor and feeder space per pig were 0.650 m2 and 4 cm and 0.325 m2 and 2 cm for the single- and double-stocked treatments, respectively. In Study 2, pigs (n = 1,458) were used in a randomized complete block design to evaluate two initial stocking treatments (Single [27 pigs] vs Double [54 pigs] stocked for 10 wk after weaning) on pig performance from weaning (4.8+/-0.01 kg BW; 15 d of age) to harvest (24 wk after weaning). Floor and feeder space per pig were 0.640 m2 and 3.4 cm and 0.320 m2 and 1.7 cm for single- and double-stocked pens, respectively. In both studies, double-stocked pigs were split at the end of wk 10 into two equal-sized groups of similar mean BW and CV of BW, and one group was moved to a different pen in the same building. In Study 1, performance was not affected (P > 0.10) by frequency of weighing. For the first 10 wk after weaning, the Double compared to the Single treatment had lower ADG (7.7 and 7.9%, for Studies 1 and 2, respectively; P < 0.001) and lighter pigs at wk 10 (6.8 and 7.3%, respectively; P < 0.001). During the first 10 wk in Study 1, Double compared to the Single pigs had lower ADFI (7%; P < 0.001) but similar gain:feed (P > 0.10). From wk 11 to harvest, pigs on Double and Single treatments had similar (P > 0.10) ADG in both studies and, in Study 1, ADFI was unaffected by initial stocking treatment, but double-stocked pigs had greater gain:feed (4%, P < 0.01). Double-stocked pigs required an additional 2 d to reach a fixed harvest BW (P < 0.05) in Study 1 and were lighter (4%; P < 0.05) at 24 wk after weaning in Study 2. Carcass measures were similar (P > 0.10) for double- and single-stocked pigs. Double-stocked pigs that were moved at the end of 10 wk had growth performance similar (P > 0.10) to those that remained in the original pen. In summary, double stocking reduced growth rate to 10 wk after weaning but subsequently had no effect on growth rate and improved feed efficiency.

A luteolytic interaction between estradiol benzoate and prostaglandin F2 alpha in cattle.

A possible luteolytic interaction between prostaglandin F2 alpha (PGF2 alpha) and estradiol benzoate (E2B) in cattle was investigated by randomly assigning 20 heifers to one of four groups of a 2 x 2 factorially designed experiment. The treatments for the groups consisted of im administration of: 1) 200 micrograms of E2B, given twice daily on d 10, 11 and 12 of the estrous cycle plus 7 mg PGF2 alpha, given at a separate site, but concurrently with the last injection of E2B; 2) the vehicles for E2B (sesame oil) and PGF2 alpha (saline); 3) E2B and saline and 4) sesame oil and PGF2 alpha. Administration of both E2B and 7 mg PGF2 alpha resulted in luteolysis as evidenced by a shorter mean length of the estrous cycle (P less than .05) when compared with the vehicle-treated control group, and a decline in systemic concentrations of progesterone to less than 1 ng/ml in four of five animals. Administration of PGF2 alpha with sesame oil was luteolytic in only one of five animals and E2B plus saline had no effect on the mean length of the estrous cycle or systemic concentrations of plasma progesterone. These observations suggested a luteolytic interaction between E2B and PGF2 alpha. This luteolytic interaction was examined further in a second experiment. Corpora lutea was removed 12 h after treatment with 200 micrograms E2B or .5 ml sesame oil, administered twice on d 10, 11 and 12 of the cycle, and incubated with luteinizing hormone (LH) and PGF2 alpha in vitro. The effect of both LH and PGF2 alpha was to increase progesterone synthesis (P less than .01), and this effect was observed irrespective of E2B pretreatment. These findings were not consistent with the hypothesis that the luteolytic site of action for either E2B or PGF2 alpha was inhibition of the steroidogenic effects of LH as assessed under in vitro conditions.

Effects of sow-crate design on health and performance of sows and piglets.

The effects of sow-crate design on certain health and performance traits of 211 sows and their piglets were evaluated with a 2 X 2 X 4 factorial arrangement of crate width (narrow [N = 55 cm] or wide [W = 64] between lowest horizontal pipes), length (short [S = 183 cm] or long [L = 198] from rump stop to front gate) and side type (lower side of sow crate "fingered" [F], "bowed" bottom bar--marking the sow zone 19.3 cm wider at the bottom--20 cm above the floor [B], or straight bottom bar 20 cm [S20] or 25 cm above the floor [S25]). Between d 107 to 110 postcoitum and d 21 postpartum, no crate design variable affected the sow's body-weight change, but side type tended to affect the most prominent head-neck and leg integumentary lesions. Number of stillborn piglets/litter was greater with W crates than with N, except with crates having S20 sides, and was greater with L crates than with S. More piglets were crushed to death in W crates than N crates, and stillbirth frequency was greater in L crates than in S, but overall preweaning piglet mortality was affected by no crate-design feature. At both 7 and 21 d of age, piglets' knee lesions were most severe with S20 crates and least with S25, whereas face-lesion score was unaffected by crate design. Piglet body weight at age 21 d was least with S20 crates and greatest with F and S25. No crate-design variable affected within-litter variation in piglet growth rate. Sow-crate design affected important health and performance traits of piglets through postnatal d 21.

An inherited platelet function defect in a Simmental crossbred herd.

An inherited bleeding disorder, resembling Simmental hereditary thrombopathy (SHT), has been identified in a Simmental crossbred herd. In an affected bull calf, initially evaluated because of excessive bleeding from a vaccination site, the platelet aggregation response to the agonist, adenosine-diphosphate (ADP) was essentially absent and the aggregation response to platelet activating factor (PAF16) was reduced by at least 70%. The initial laboratory assessment of platelet function in the dam and sire yielded results which were within normal limits. The sire was not available for further testing. The dam, also a daughter of this sire, was subsequently shown to have a partially reduced aggregation response to ADP. Of 18 other offspring of the sire evaluated, 6 were also identified as having a partially impaired aggregation response. The maximum aggregation response to ADP and PAF16 in these 6 calves was approximately 50% of the level exhibited by unaffected animals. In contrast, the coagulation profiles were normal for all animals except for a heifer calf which also exhibited a partially impaired aggregation response. The plasma level of the coagulation protein, factor XI, was reduced in this heifer calf which suffered a fatal hemorrhage following dehorning. This report appears to be the 1st to have identified animals putatively heterozygous for SHT on the basis of the in vitro platelet aggregation response to ADP.

Nephrotoxicity of amphotericin B in dogs: a comparison of two methods of administration.

Two methods of administration of amphotericin B were compared for their ability to produce nephrotoxicity in 12 dogs. Six dogs received six alternate day doses of amphotericin B: 1 mg/kg administered as a rapid bolus in 25 mL 5% dextrose in water. Another six dogs received alternate day treatments of the same dose of amphotericin B in 1 L 5% dextrose in water over 5 h. Both treatment groups experienced significant reductions in glomerular filtration rate, as measured by inulin clearance, 24 h endogenous creatinine clearance, serum creatinine and serum urea. This reduction in glomerular filtration rate was most marked in the group receiving the drug as a rapid bolus. The inulin clearances decreased from 3.54 +/- 0.30 mL/min/kg (means +/- SEM) on day 0 to 1.15 +/- 0.25 mL/min/kg on day 12 in the slow infusion group and from 3.24 +/- 0.25 mL/min/kg on day 0 to 0.46 +/- 0.11 mL/min/kg on day 12 in the rapid bolus group. Renal lesions characteristic of amphotericin B administration were observed in all dogs tested. The dogs which received amphotericin B as a rapid bolus had a significantly greater number of tubular lesions than the slow infusion group. Systemic side effects, such as vomiting, diarrhea and weight loss, were observed in both treatment groups but were most severe in the rapid bolus group.(ABSTRACT TRUNCATED AT 250 WORDS)

Reproductive consequences of deficiency of uridine monophosphate synthase in Holstein cattle.

Cattle heterozygous for deficiency of uridine monophosphate synthase required more breeding services per calving when mated to other heterozygotes than did matings of normal cattle. Gestation length, number of breeding services per calving, and days from breeding to pregnancy examination were monitored on 759 complete gestations, 76 false-positive pregnancy diagnoses, 14 false-negative pregnancy diagnoses, and 413 negative pregnancy diagnoses in a dairy herd between 1983 and 1987. For complete gestations, 15 heterozygote x heterozygote matings required 3.13 +/- 0.37 breeding services per calving, which was significantly more than the 2.05 +/- 0.05 breeding services required for normal x normal matings; gestation length and days from breeding to pregnancy examination were similar between mating types. For false-positive pregnancy diagnoses, females diagnosed pregnant, but subsequently found not to be pregnant, 5 heterozygote x heterozygote matings averaged 51 +/- 23 days of gestation, which was less than the 93 +/- 6 days required for 71 normal matings; services and days from breeding to pregnancy examination were similar between mating types. All false-negative pregnancy diagnoses, females diagnosed not pregnant but later found to be pregnant, were made on cattle with normal matings. For negative pregnancy diagnoses, heterozygous matings averaged 0.3 more breeding services per examination than normal matings.

Efficacy of flunixin meglumine for the treatment of endotoxin-induced bovine mastitis.

The clinical effect of flunixin meglumine administration was determined in cows with acute mastitis induced by intramammary administration of endotoxin. In 12 lactating cows, 10 micrograms of Escherichia coli 026:B6 endotoxin were administered via a teat cannula into the teat cistern of single randomly selected rear quarters. Cows were challenge exposed as pairs. One cow in each pair was administered parenteral flunixin meglumine (6 cows) and 1 cow per pair was administered saline solution (6 cows). Multiple doses (7) of 1.1 mg of flunixin meglumine/kg of body weight or saline solution were administered at 8-hour intervals beginning 2 hours after endotoxin. Cow and quarter clinical signs as well as milk somatic cell concentrations, bovine serum albumin, electrical conductivity, and milk production were determined before and for 14 days after endotoxin inoculation. Intramammary endotoxin produced signs characteristic of acute coliform mastitis. Quarter and systemic abnormalities occurred and milk production was reduced by approximately 50% at 12 hours after endotoxin. Flunixin meglumine therapy significantly (P less than or equal to 0.05) reduced rectal temperatures and quarter signs of inflammation and improved clinically graded depression when compared with these signs in saline solution-treated controls. Milk production and laboratory indicators of inflammation in milk were not significantly (P greater than 0.05) different for flunixin meglumine vs saline solution controls. The clinical response observed was consistent with the antipyretic, analgesic, and anti-inflammatory properties of flunixin meglumine.