Effect of feed restriction and hypothermia on fetal mice

Abstract only availableLow birth weights result in high mortality in highly prolific pigs. Anecdotal evidence in sheep and cattle suggests restricting feed early in gestation and/or cooling late in gestation increase birth weights. Therefore, the objective of this study was to determine the effect of early gestation feed restriction in combination with late gestational chilling on term decidual and fetal weights, and prenatal survival in mice. The study used 37 ICR male mice each mated with 4 females except for one male with 5 females. Once a female had a vaginal plug, she was removed from the male and placed into her own cage. Pregnant females were allocated to four groups: full feed-normal temperature, full feed-chilled temperature, restricted feed-normal temperature, and restricted feed-chilled temperature (n = 18, 19, 23 and 16, respectively). The restricted feed females were fed 80% of their previous five day's average intake from day 5 to 10 of gestation while full feed females were fed ad libitum. All females were fed ad libitum from day 10 to 18. On day 14 the chilled temperature females were moved to an 18 °C environmental chamber while the normal temperature females were housed at 22 °C. On day 18 the females were sacrificed and the fetal weight, respective fetus's decidual weight, and number of corpora lutea and implantations were recorded. During restriction, intake of restricted mice was 68% of full feed mice. Immediately after restriction, there was a compensatory increase in intake by restricted mice, but overall, restricted mice consumed 93.8% that of full feed mice. There were no significant differences in survival rates among the four groups. There was also no significant difference between chilled temperature and normal temperature for decidual or fetal weights. However, full feed mice had greater (P<0.05) birth weights than restricted feed mice (1.36 vs. 1.31 g). In conclusion, restricting feed and chilling during gestation did not increase birth weights in mice.F.B. Miller Undergraduate Research Program in Animal Science

Breeding and genetics (1993)

New 9/93/7M

Crossbreeding systems for small herds of beef cattle (1993)

Crossbreeding in commercial beef cattle production improves efficiency through heterosis and breed complementation. Heterosis or hybrid vigor is an advantage in performance of crossbreds compared to the average performance of the parental breeds. Heterosis is particularly strong for traits that are lowly heritable such as conception rate, preweaning livability of calves and preweaning growth.Reviewed December 1993 -- Extension website

Concurrent and long-term associations between the endometrial microbiota and endometrial transcriptome in postpartum dairy cows

peer-reviewedBackground Fertility in dairy cows depends on ovarian cyclicity and on uterine involution. Ovarian cyclicity and uterine involution are delayed when there is uterine dysbiosis (overgrowth of pathogenic bacteria). Fertility in dairy cows may involve a mechanism through which the uterine microbiota affects ovarian cyclicity as well as the transcriptome of the endometrium within the involuting uterus. The hypothesis was that the transcriptome of the endometrium in postpartum cows would be associated with the cyclicity status of the cow as well as the microbiota during uterine involution. The endometrium of first lactation dairy cows was sampled at 1, 5, and 9 weeks postpartum. All cows were allowed to return to cyclicity without intervention until week 5 and treated with an ovulation synchronization protocol so that sampling at week 9 was on day 13 of the estrous cycle. The endometrial microbiota was measured by 16S rRNA gene sequencing and principal component analysis. The endometrial transcriptome was measured by mRNA sequencing, differential gene expression analysis, and Ingenuity Pathway Analysis. Results The endometrial microbiota changed from week 1 to week 5 but the week 5 and week 9 microbiota were similar. The endometrial transcriptome differed for cows that were either cycling or not cycling at week 5 and cyclicity status depended in part on the endometrial microbiota. Compared with cows cycling at week 5, there were large changes in the transcriptome of cows that progressed from non-cycling at week 5 to cycling at week 9. There was evidence for concurrent and longer-term associations between the endometrial microbiota and transcriptome. The week 1 endometrial microbiota had the greatest effect on the subsequent endometrial transcriptome and this effect was greatest at week 5 and diminished by week 9. Conclusions The cumulative response of the endometrial transcriptome to the microbiota represented the combination of past microbial exposure and current microbial exposure. The endometrial transcriptome in postpartum cows, therefore, depended on the immediate and longer-term effects of the uterine microbiota that acted directly on the uterus. There may also be an indirect mechanism through which the microbiome affects the transcriptome through the restoration of ovarian cyclicity postpartum

PREWEANING SURVIVAL IN SWINE: HERITABILITY OF DIRECT AND MATERNAL EFFECTS

The heritabilities of direct and maternal effects on litter survival to weaning (LS) were estimated from records of 1,243 litters of pigs from the Nebraska Gene Pool population born from 1968 to 1981. Heritabilities were estimated by: (1) weighted least-squares regressions of average survival for litters of sons on average survival for litters of their sire, (2) nested analysis of variance with LS fitted to a model including year-line and sire of litter, (3) weighted least-squares regression of average survival for the litter of daughters on the survival of the litter of their dam and (4) nested analysis of variance with LS fitted to a model including year-line and sire of dam of litter. Analyses were conducted with and without adjustment for litter size born. Estimates of the heritability of direct effects from methods 1 and 2 were negative. Adjustment to a common litter size born had no effect. If direct effects are considered to be negligible, as indicated by these analyses, then LS may be considered a trait of the dam. The heritability of maternal effects estimated from daughter-dam regression was .01 ± .02. The estimate of heritability of maternal effects obtained from analysis 4 was .07 ± .03. Again, there were no effects from adjustment to a common litter size born. These estimates were not significantly different and the pooled estimate was .03 ± .02. These analyses indicate that some additive genetic variance might exist for maternal effects but none for direct effects on LS. Selection for increased survival is not expected to be successful

Use of South African native plants to alleviate heat stress-induced subfertility [abstract]

Heat stress causes subfertility in males, contributing to significant economic losses in the U.S. dairy, beef, and swine industries. Scientist at the University of Western Cape recommended four herbs as candidates to mitigate the effects of heat stress: Sutherlandia (S), Tulbaghia violacea (T), Helichrysum (H) and Artemesia afra (A). Our objectives are to determine if these herbs reduce phenotypic effects caused by heat stress and determine how they effect gene expression changes associated with heat stress produced subfertility. Mature ICR male mice (n=36) were randomly assigned to one of six treatment groups: 1) thermoneutral (21°C) control; 2) heat stress (35°C for 24 hr = d 0) control; and 3-6) heat stress following five feedings of S, T or H (dried plants mixed 1:3 with mouse chow), and via water for A, respectively. Males were hemicastrated (d 1) and testes were collected for RNA isolation. Males proven fertile were each mated to 8 ICR females from d 18 to 26 post heat stress, a period when subfertility is expected. Pregnant females were sacrificed on d 17 of gestation. Post-stress body temperature was reduced in A, T and S when compared to the heat stress group. Body weight and consumption of S, T and H, but not A, were also less than controls (P<0.05). Compared to thermoneutral, heat stress reduced the number of females mated, except group A, which was similar to thermoneutral (P<0.1), but had no effect on other reproductive measures. We will quantify the expression of previously identified genes through real time RT-PCR

Ovarian function and the establishment and maintenance of pregnancy in dairy cows with and without evidence of postpartum uterine disease

Uterine disease early postpartum reduces fertility during the breeding period. One potential mechanism involves the reduced functional capacity of the uterus to support pregnancy. A second potential mechanism involves damage to ovarian follicles associated with systemic inflammation. We categorized lactating Holstein cows into healthy (n = 63) and diseased (n = 39) uterus groups based on the percentage of polymorphonuclear neutrophils in the uterine lumen during the second and third month postpartum and evaluated the functionality of their ovaries and their capacity to establish and maintain pregnancy. Cows were enrolled in a timed artificial insemination protocol (Presynch Ovsynch) so that the first artificial insemination was approximately 75 d postpartum. Ovarian follicles and corpora lutea were counted and measured using transrectal ultrasound, ovulatory responses were assessed, and luteal phase progesterone concentrations were measured. Pregnancy was detected on d 18, 20, 22, 25, 32, and 45 through chemical (d 18 to 25) or ultrasonographic methods (d 32 and 45). The percentage of cows ovulating during the Presynch period; the number, diameter, and ovulatory capacity of follicles during the Ovsynch period; and plasma progesterone concentrations following ovulation were similar for healthy and diseased cows. The initial period of pregnancy establishment (d 18 to 22) appeared to be unaffected by disease because a similar percentage of healthy and diseased cows were pregnant during this period. Embryonic loss occurred in both healthy and diseased cows after d 22. Based on a relatively small number of pregnancies (n = 30 healthy and n = 17 diseased), the cumulative embryonic loss after d 22 was greater in diseased compared with healthy cows. In short, uterine disease as defined in this study did not affect cyclicity, ovarian follicular growth, or plasma progesterone concentrations. Percentages of healthy and diseased cows that were pregnant were similar from d 18 to 22 after artificial insemination. Greater embryonic loss was observed after d 22 in diseased compared with healthy cows, but this observation was based on a small number of pregnancies and should be studied further in larger trials with greater statistical power.UCR::Vicerrectoría de Docencia::Ciencias Agroalimentarias::Facultad de Ciencias Agroalimentarias::Escuela de Zootecni

Genetic and phenotypic trends for growth traits of buffaloes in Brazil

The objectives this paper were to estimate genetic parameters and genetic and phenotypic trends of birth weight (BWT) and weights adjusted to 205 (WT205), 365 (WT365) and 550 (P550) days of age of beef buffaloes born from 1985 to 2003 in Brazil. For BWT and WT205 the model included direct and maternal genetic and maternal environment as random effects and contemporary and genetic groups as fixed effects. For WT365 and WT550 the same model was used except without direct maternal and maternal environmental effects. The genetic and phenotypic trends were estimated by regression of means of dependent variables on birth year of animals Regressions were obtained by using two methodologies: 1) linear regression; and 2) non-parametric splined regression. The direct heritability estimates were 0.09, 0.45, 0.46 and 0.58 for BWT, WT205, WT365 and WT550, respectively. The direct genetic trends from linear regression were 0.01, 0.23, 0.58 and 1.40 kg per year for PN, WT205, VVT365 and WT550, respectively (P<0.001 for all). Phenotypic trends were strongly positive while genetic trends were consistently positive but small. Genetic parameters indicate potential for increased rate of genetic change with full implementation of genetic improvement programs