K. R. Stewart

Effects of rapid temperature fluctuations prior to breeding on reproductive efficiency in replacement gilts.

Rapidly cooling pigs after heat stress (HS) results in a pathophysiological condition, and because rapid temperature fluctuations may be associated with reduced reproductive success in sows, it lends itself to the hypothesis that these conditions may be linked. Objectives were to determine the effects of rapid cooling on thermal response and future reproductive success in pigs. Thirty-six replacement gilts (137.8±0.9kg BW) were estrus synchronized and then 14.1±0.4 d after estrus confirmation, pigs were exposed to thermoneutral conditions (TN; n=12; 19.7±0.9°C) for 6h, or HS (36.3±0.5°C) for 3h, followed by 3h of rapid cooling (HSRC; n=12; immediate TN exposure and water dousing) or gradual cooling (HSGC; n=12; gradual decrease to TN conditions) repeated over 2 d. Vaginal (TV) and gastrointestinal tract temperatures (TGI) were obtained every 15min, and blood was collected on d 1 and d 2 during the HS and recovery periods at 180 and 60min, respectively. Pigs were bred 8.3±0.8 d after thermal treatments over 2 d. Reproductive tracts were collected and total fetus number and viability were recorded 28.0±0.8 d after insemination. HS increased TV and TGI (P=0.01; 0.98°C) in HSRC and HSGC compared to TN pigs. During recovery, TV was reduced from 15 to 105min (P=0.01; 0.33°C) in HSRC compared to HSGC pigs, but no overall differences in TGI were detected (P<0.05; 39.67°C). Rapid cooling increased (P<0.05) TNFα compared to HSGC and TN pigs during recovery-d 1 (55.2%), HS-d 2 (35.1%), and recovery-d 2 (64.9%). Viable fetuses tended to be reduced (P=0.08; 10.5%) and moribund fetuses tended to be increased (P=0.09; 159.3%) in HSRC compared to HSGC and TN pigs. In summary, rapid cooling prior to breeding may contribute to reduced fetal viability and reproductive success in pigs.

Effect of natural betaine on estimates of semen quality in mature AI boars during summer heat stress

This study evaluated the effect of supplemental dietary betaine at three concentrations (0.0%, 0.63% and 1.26%) on semen characteristics, quality and quality after storage on boars. The trial was conducted between 22 July and 1 October 2014 in a boar stud located in Oklahoma. Boars were blocked by age within genetic line and randomly allotted to receive 0% (CON, n (line T)=22, n (line L)=10), 0.63% (BET-0.63%, n (line T)=21, n (line L)=6) or 1.26% (BET-1.26%, n (line T)=23, n (line L)=7). The diets containing betaine were fed over 10 weeks, to ensure supplemental betaine product (96% betaine) daily intakes of 16.34 and 32.68g, for the BET-0.63% and BET-1.26% diets, respectively. Serum homocysteine concentrations were less for animals with betaine treatments (P=0.016). Rectal temperatures of the boars were unaffected by betaine diets. Betaine tended to increase total sperm in the ejaculates when collectively compared with data of the control animals (P=0.093). Sperm morphology analysis indicated there was a greater percent of sperm with distal midpiece reflex (P=0.009) and tail (P=0.035) abnormalities in boars fed the BET-1.26% than boars fed the BET-0.63% diet. Betaine concentration in the seminal plasma was greater in boars with betaine treatments, with animals being fed the 0.63% and 1.26% diets having 59.2% and 54.5% greater betaine concentrations in seminal plasma as compared with boars of the control group (P=0.046). In conclusion, betaine supplementation at 0.63% and 1.26% tended to increase sperm concentration in the ejaculates by 6% and 13%, respectively, with no negative impacts on semen quality when 0.63% of betaine was included in the diet.

Use of heterospermic inseminations and paternity testing to evaluate the relative contributions of common sperm traits and seminal plasma proteins in boar fertility

The objective of this study was to evaluate relationships between common semen quality estimates including sperm motility, sperm morphology, spontaneous capacitation status and seminal plasma proteins and boar fertility using heterospermic inseminations and subsequent paternity testing. All boars (n=12) used in the study had excellent semen quality (≥70% normal sperm) that resulted in average farrowing rates and litter sizes of 88.9±0.7% and 11.7±0.1 pigs, respectively. Their ejaculates were combined to make heterospermic insemination doses in such a way that each boar was tested against all of his contemporaries. The proportion of piglets sired by each individual was used to separate boars into three fertility groups: High (71.6±4.8%; n=3); Medium (51.6±3.8%; n=6); and Low (25.2%±5.3%; n=3). Ejaculates from High fertility boars had more motile sperm with normal acrosomes that moved faster in a straight-line and were more likely to undergo an acrosome reaction (p≤0.05) compared with their counterparts in the Low fertility group. Ejaculates from High fertility boars contained the greatest concentrations of three seminal plasma proteins (25.9kD/5.9pI; 55.1kD/4.8pI; and 70.1kD/5.2pI; p≤0.05), whereas concentrations of a 19.1kD/6.8pI were highest in semen from Low fertility boars (p≤0.05). Multiple regression analyses indicated that concentrations of the 25.9kD/5.9pI seminal plasma protein explained 66% of the variation observed in the proportion of pigs sired within a litter among boars (p≤0.00001). These results demonstrate that heterospermic inseminations and subsequent paternity testing is an effective technique for defining relationships between common semen quality tests and fertility, especially in situations where reproductive performance of all the boars is high. Motility, normal acrosome morphology, average linear velocity of motile sperm, and the proportion of sperm capable of an acrosome reaction were all positively associated with boar fertility. However, concentrations of a 25.9kD/5.9pI seminal plasma protein were the best single semen characteristic for ranking boars in terms of their fertility.

Diet Impacts Pre-implantation Histotroph Proteomes in Beef Cattle

In ruminants, the period from fertilization to implantation is relatively prolonged, and the survival of embryos depends on uterine secretions known as histotroph. Our objective was to determine if the pre-breeding diet affected histotroph proteomes in beef cattle. Cows were assigned to one of four diets: a control diet (CON), a high-protein diet (PROT), a high-fat diet (OIL), or a high-protein and high-fat diet (PROT + OIL). After 185 days on these diets, an intravaginal progesterone implant (CIDR) was inserted for 7 days. At 9 days after CIDR removal, animals with a corpus luteum were selected ( n = 16; 4 per treatment). Proteins were isolated from the histotroph collected by uterine lavage and analyzed with liquid chromatography-tandem mass spectrometry. Over 2000 proteins were expressed ( n ≥ 3 cows per treatment), with 1239 proteins being common among all of the groups. There were 20, 37, 85, and 123 proteins unique to CON, PROT + OIL, PROT, and OIL, respectively. Relative to CON, 23, 14, and 51 proteins were differentially expressed in PROT + OIL, PROT, and OIL, respectively. Functional analysis found that 53% of histotroph proteins were categorized as extracellular exosome, 3.28% as cell-cell adhesion, and 17.4% in KEGG metabolic pathways. Differences in proteomes among treatments support the idea that pre-breeding diet affects histotroph. Understanding the impact of diet on histotroph proteins may help improve conception rates.

The potential of identifying replacement gilts by screening for lipid biomarkers in reproductive tract swabs taken at weaning

ABSTRACT Sow longevity affects economic returns to pork producers. The cost of gilt replacements is substantial and sows with greater than three litters have lower costs per pig produced. An early marker of reproductive potential would facilitate early identification of superior females, and likely increase sow longevity. Gilts raised in small litters have greater reproductive competence, but mechanisms associated with increased reproductive responses are not fully understood. Here, early postnatal development of the gilts reproductive tract is described, and a brief review of literature is presented to support that factors in colostrum regulate the developmental trajectory of the gilts uterine tissues. We propose that, similar to the uterus, nutritional environment likely affects the postnatal developmental programme of the vagina. A metabolomics approach, multiple reaction monitoring -profiling, for biomarker discovery is described, along with evidence that lipids present in vaginal samples are differentially expressed in gilts exposed to colostrum versus milk replacer fed. These exploratory studies indicate that the vaginal cell lipidome may reflect the postnatal nutritional environment, which defines to a large extent the gilts reproductive potential. Together findings support further investigations to identify biomarkers predictive of fertility outcomes in the metabolome of gilt reproductive tracts.

In utero heat stress causes reduced testicular area at puberty, reduced total sperm production, and increased sperm abnormalities in boars

In utero stress has been shown to negatively affect intact male rats and mice, though very little research has been conducted in boars. The objectives of the present studies were to determine the effects of in utero heat stress (IUHS) on postnatal development and the response to postnatal heat stress of boars. Ten boars were selected at weaning from litters subjected to IUHS or in utero thermoneutral (IUTN) during 30-60 days of gestation. The boars were evaluated for reproductive performance from birth through 57 weeks of age (WOA). Testicular area tended to be smaller for IUHS boars compared to IUTN boars at 24 WOA (P = 0.080). Libido did not differ for IUHS or IUTN (P = 0.818). Total sperm production was reduced in IUHS boars compared to IUTN boars (P ≤ 0.038). Semen volume and semen concentration did not differ (P ≥ 0.469 and P ≥ 0.664, respectively). Total motility and progressive motility did not differ for IUHS and IUTN boars (P ≥ 0.430 and P ≥ 0.652, respectively). In utero heat stressed boars had a greater incidence of sperm with tail abnormalities than IUTN (P ≤ 0.042). In utero heat stressed boars had a lower incidence of sperm with proximal droplets following mild, postnatal heat stress compared with IUTN (P = 0.005). In utero heat stress resulted in significant reductions in sperm production and increased sperm abnormalities in boars. The IUHS boars may be slightly more tolerant to postnatal heat stress, though more research is needed.

Using corn gluten feed in post-partum diets of young beef cows to optimize reproductive performance

Abstract Forty-eight primiparous and diparous Angus-Simmental cows were fed 1 of 3 diets; 1) total mixed ration (TMR) based of corn silage and corn stalks (CON), 2) TMR with 3.3 kg/d DM of corn gluten feed (CGF; MID), or 3) TMR with 6.7 kg/d DM of CGF (HIGH). From 11 ± 5 days post-partum (DPP) to 105 ± 5 DPP, all diets were formulated to be isocaloric for a post-partum ADG targeted at 0.22 kg, but CP exceeded requirements in both CGF diets. Blood samples were collected from cows starting at trial initiation until estrous synchronization for determination of plasma progesterone concentration (7 d intervals), as an indicator of resumption of cyclicity, as well as for plasma urea nitrogen (PUN; 21 d intervals). Milk production was assessed at 62 ± 5 DPP via a weigh-suckle-weigh procedure, and milk samples were collected at 64 ± 5 DPP for composition analysis. A 5 d Co-Synch + Control Internal Drug Release (CIDR) protocol was used and cows were bred by timed artificial insemination (TAI). Trans-rectal ultrasonography was used for the evaluation of the dominant follicle at TAI, as well as pregnancy diagnosis. Nineteen days post-TAI, cow and calf pairs were managed as a single group until weaning (205 ± 5 DPP) and exposed to natural mating for a total of a 60 d breeding season. Dam ADG was not significantly different among treatments (P = 0.849), but, DMI decreased with increasing CGF in the diet (P = 0.049). There were no differences in final BW (P = 0.779), however, final BCS was lower in the HIGH treatment when compared to the MID (P = 0.042). Milk production (P = 0.457), as well as, milk components (P ≥ 0.188) were not different, with the exception of milk fat, which tended to be greater in the HIGH treatment (P = 0.059) when compared to the MID. A treatment by week interaction (P < 0.0001) was found for PUN concentrations. Concentrations were greater in the HIGH treatment compared to the MID treatment at 63, 84, and 105 d, and greater than the CON treatment at all time points except d-42. There were no differences in resumption of cyclicity (P = 0.419), dominant follicle (P = 0.648), or TAI conception rates (P = 0.761). However, season long pregnancy rates were significantly greater in the CGF treatments when compared to the CON (P = 0.009). In summary, feeding high or intermediate amounts of CGF neither has a positive nor negative effect on TAI conception rates of beef cows, however, it positively affected season long pregnancy.

Effect of dried distiller’s grains plus solubles in postpartum diets of beef cows on reproductive performance of dam and heifer progeny

Forty-eight primiparous and multiparous cows were fed a silage-based total mixed ration (TMR; CON), a TMR with 2.5 kg/d DM dried distillers grains plus solubles (DDGS; MID), or a TMR with 4.7 kg/d DM DDGS (HIGH) from 8.5 ± 4 to 116 ± 4 d postpartum (DPP). All diets were formulated to be isocaloric for a postpartum ADG targeted at 0.22 kg, whereas CP exceeded requirements in both diets containing DDGS. Blood samples were collected from dams at 7- and 21-d intervals for progesterone concentration (resumption of cyclicity) and plasma urea nitrogen, respectively. A weigh-suckle-weigh procedure was used to measure milk production, and samples were collected for milk composition and fatty acid profile. A 5-d Co-Synch + controlled internal drug release (CIDR) protocol was used, and cows were bred (97 ± 4 DPP) by timed AI (TAI). Ultrasonography was used for measurement of the largest antral follicle at TAI and pregnancy diagnosis. Nineteen days after TAI, cow and calf pairs were managed as a single group until weaning and exposed to natural mating for a total of a 60-d breeding season. Starting at weaning, blood samples were collected from heifer offspring at 7-d intervals for progesterone concentration used as an indicator of puberty. A 5-d Co-Synch + CIDR protocol was used, and heifers were bred by TAI. Transrectal ultrasonography was used for measurement of the largest antral follicle at TAI and antral follicle count (AFC) at CIDR device insertion as well as pregnancy diagnosis. There were no differences in dam ADG ( = 0.364); however, DMI decreased with increasing DDGS ( < 0.0001), resulting in an increased feed efficiency ( = 0.042). Milk fat and lactose tended to increase with the addition of DDGS in the diet ( ≤ 0.055), and milk urea nitrogen increased ( < 0.001). There were no differences in resumption of cyclicity ( = 1.00) or diameter of the largest antral follicle ( ≥ 0.372). Timed AI pregnancy rates were not different with the addition of DDGS in the diet ( ≥ 0.174). Heifer ADG was reduced with DDGS during late lactation ( = 0.031). Heifer AFC had a tendency to increase with increasing DDGS ( = 0.081), with no impacts on dominant follicle diameter at TAI ( = 0.161). Heifer TAI pregnancy rate also was not different among treatments ( = 0.508). Overall, feeding 4.7 kg/d DM of DDGS to dams during early lactation increases feed efficiency of the dam, with minor statistically significant effects on dam or heifer offspring reproduction.