Reproductive performance of single fixed-time inseminated sows with semen doses submitted to different semen storage times.

This study aimed to evaluate the reproductive performance of sows submitted to single fixed-time insemination (SFTAI) using boars according to capacity for liquid in vitro semen preservation, type of extender, and storage time. Boars (n = 12) were classified into two groups based on progressive motility (PM) at 120 h of semen storage: low (PM - 64.5%) - and high-preservation (PM - 83.9%) capacity for semen storage. Weaned sows (n = 397, parity - 1 to 7) were inseminated (1.5×109 sperm cells) in a factorial design: two classes of boars (low- or high-preservation), two types of extenders (short- or long-term), and two semen storage times at insemination (24 or 72 h). An adapted triptorelin acetate protocol was used for SFTAI. Total sperm motility (TM) and PM at insemination were greater in high-preservation boars at 72 h compared with low-preservation boars at 24 or 72 h (P < 0.01). Short- or long-term extender did not affect (P ≥ 0.68) TM and PM in high-preservation boars; however, long-term extender improved these parameters in low-preservation boars (P < 0.01). Pregnancy and farrowing rates were not affected by groups (P > 0.05). Total piglets born (TPB) was reduced (P = 0.05) in low-preservation boars with 72 h of storage (13.6 ± 0.5) compared to high-preservation boars with semen stored for 24 or 72 h (15.2 ± 0.5 and 15.5 ± 0.5, respectively). The low-preservation boars reduced the TPB in sows submitted to SFTAI, and this reduction was greater using semen stored for 72 h.

Altrenogest treatment during the last week of lactation on ovarian traits and subsequent reproductive performance of primiparous and multiparous sows.

High-quality follicles result in larger corpora lutea (CL), producing more progesterone, and having a fundamental role in pregnancy maintenance. For some sows, follicular growth takes place during lactation, and follicle selection occurs under a catabolic environment. As altrenogest inhibits follicular development, this study aimed to evaluate follicular growth, CL size, estrus expression, and subsequent reproductive performance of sows treated with altrenogest during the last seven days of a three-week lactation. A total of 81 primiparous and 319 multiparous sows were allocated to two treatments: CONT (control group) and ALT (20 mg of altrenogest/day during the last seven days of lactation). Subsamples of 20 primiparous sows and 97 multiparous were randomly selected to evaluate follicular growth and 26 multiparous sows for serum progesterone analysis at day 21 of gestation. On day 21 of pregnancy, CL measurement was performed by ultrasound. Once in estrus, sows were post-cervically inseminated with pooled semen doses with 1.5 × 109 sperm cells at estrus onset and every 24 h during the standing reflex period. Sows not showing estrus until 10 days after weaning were considered in anestrus. The variables weaning-to-estrus interval, CL size, litter size in the subsequent cycle, and piglet birth weight were evaluated using the GLIMMIX procedure and compared using the Tukey-Kramer test. Anestrus, pregnancy, farrowing, and adjusted farrowing rate were evaluated as binary responses using logistic regression. Follicular size was analyzed as a repeated measure during treatment and after weaning. Treatment was considered as a fixed effect. During the treatment period, follicular size was smaller in ALT sows than CONT sows (3.29 vs. 3.52 mm; P < 0.001). However, after treatment, ALT sows showed a larger follicular size than CONT sows (5.30 vs. 5.03 mm; P ≤ 0.01). There were less ALT sows showing estrus than CONT sows on days three (1.03 vs. 4.57%) and four (55.38 vs. 68.02%) after weaning (P ≤ 0.05), respectively. At 21 days after insemination, ALT sows showed larger CL size and lower CL size variation (P < 0.01) than CONT sows. Anestrus rate, pregnancy rate, farrowing rate, adjusted farrowing rate, litter size in the subsequent cycle, piglet birth weight, litter birth weight, and birth weight variation did not differ between treatments (P ≥ 0.14). In conclusion, altrenogest treatment during the last week of lactation concentrated estrus expression on day five after weaning, larger follicle and CL sizes; however, with no improvement in reproductive performance.

Sow-related factors affecting the postweaning feed intake in Landrace × Large White females.

During the weaning-to-estrus interval (WEI), a high feeding level is usually offered to recover losses due to lactational catabolism. However, several factors can affect the appetite, possibly impairing the efficacy of this strategy. This study aimed to investigate the effect of sow-related factors on average daily feed intake (ADFI) during WEI in 142 primiparous and 458 multiparous sows. After weaning, the sows received 4.3 kg/day of feed and the wastage was recorded. The ADFI after weaning was lower in primiparous than multiparous sows, and on estrous day than in 2 and 3 days preceding estrus (P ≤ 0.05). In primiparous sows, lower ADFI was observed if they had higher backfat thickness at 112 days of gestation (BFT ≥ 11.5 mm) or higher reserves at weaning (BFT ≥ 10.5 mm, caliper units ≥ 12 or ≥ 157 kg; P ≤ 0.05). Higher body reserves at the end of gestation (caliper units ≥ 12, BFT ≥ 11.0 mm, or BCS ≥ 3.0) or weaning (caliper units ≥ 13, BFT ≥ 12.5 mm) negatively affected the ADFI in multiparous sows (P < 0.04). Weaned litter size ≤ 11 piglets (P = 0.06) and shorter lactation length (P< 0.01) decreased the ADFI in primiparous sows. Greater loss in caliper units during lactation tended to reduce ADFI in primiparous and multiparous sows (P ≤ 0.07). Multiparous sows with greater losses in BFT and BCS had lower ADFI (P ≤ 0.03). The ADFI during WEI is reduced when sows are in estrus or if they have greater body reserves.

Effects of the classification of boars according to progressive sperm motility and the extender type on the reproductive performance of a single fixed-time insemination.

The study aimed to evaluate the fertility of boars according to the resistance of their semen to storage using dilution in either Short- or Long-term extender for single fixed-time insemination. From a total of 32 boars, twelve boars were classified during three semen collection (one collection/boar/week) as Low- (64.5%) or High-preservation (83.9%) capacity for maintaining progressive motility (PM) at 120 h of storage using Short-term extender. After the selection period, six ejaculates (weekly collected) from the Low- and High-preservation boars were diluted in Short- or Long-term extender (2 × 2 factorial design) for insemination and evaluation of fertility. A total of 519 weaned sows were submitted to induction of ovulation with triptorelin (OvuGel®) at 96 h post-weaning. Twenty-four hours later, estrus sows were single fixed-time inseminated (FTAI) with semen doses from the different groups of evaluation. The SAS® software was used for statistical analysis considering the class of boar, type of extender, and interaction as fixed effects. The GLIMMIX procedure was used, considering a binomial distribution for total motility (TM) and PM, binary distribution for pregnancy (PR), and farrowing rate (FR), and the total born (TB) was analyzed assuming a normal distribution with the comparison of means by Tukey-Kramer test. An interaction of class of boars and type of extender was observed for TM and PM at insemination (P < 0.001). Long-term extender increased TM in Low-preservation boars, with no effect in High-preservation boars. The ejaculates from High-preservation boars diluted in Short- or Long-term extender showed higher PM at insemination (86.8 and 87.8%, respectively) compared to those from Low-preservation boars in Short- or Long-term extender (73.2% and 77.9%, respectively). There was no effect of the interaction of boar preservation class and type of extender (P ≥ 0.163) on PR, FR or TB. However, Low-preservation boars presented lower TB (14.1 ± 0.2) compared to High-preservation boars (15.0 ± 0.2; P < 0.01). The PR (93.3 vs. 90.1) and FR (88.8 vs. 88.2) were not affected by class of Low- or High-preservation boars, respectively (P ≥ 0.187). The type of extender did not affect PR, FR, or TB (P ≥ 0.440). In conclusion, Low-preservation boars impaired the reproductive performance of single-FTAI sows by reducing TB with no apparent effect on PR or FR.

Follicular dynamic and reproductive performance of gilts submitted to estrous cycle synchronization using two different progestogen sources.

This study evaluated reproductive indicators of gilts treated with altrenogest or an intravaginal device (IVD) containing medroxyprogesterone acetate (MPA) for estrous cycle synchronization, starting the protocol on different days of the estrous cycle or replacing the IVD in the middle of treatment. In Experiment 1, 126 gilts were assigned, according to the day of treatment onset (Day 5 or 10 of the estrous cycle), to the following treatments: Control-5 (no hormone); Control-10 (no hormone); IVD-5 (IVD with MPA); IVD-10 (IVD with MPA); ALT-5 (altrenogest); or ALT-10 (altrenogest). The first day of the previous estrus was considered as Day 0 of the estrous cycle, and progestogen groups were treated for 14 d. In Experiment 2, 63 gilts were assigned to Control, ALT, or IVD groups. Progestogen treatment started on Day 10 of the estrous cycle, and the IVD was replaced after 7 d of treatment. In both experiments, no gilts expressed estrus during progestogen administration. In Experiment 1, the interval hormonal withdrawal-to-estrus (IHE) tended to be shorter when treatment started on Day 10 than on Day 5 (3.6 vs. 4.1 d, respectively; P = 0.09). The percentage of gilts expressing estrus after hormone withdrawal was lower for IVD-gilts (76.3%) compared to ALT (100%) and Control-gilts (92.9%; P ≤ 0.07). The percentage of persistent follicles (PFOL) was greater in IVD-10 (60.0%) and ALT-10 (33.3%) than CONT-10 (0.0%; P ≤ 0.06). The adjusted farrowing rate (AFR) was lower in IVD (65.5%) and ALT (80.5%) compared with CONT (97.4%; P ≤ 0.08). In Experiment 2, the IHE was longer for ALT than IVD (4.9 vs. 3.9 d, respectively; P < 0.01). No difference among groups was observed in the percentage of gilts expressing estrus (overall 86.4%), but the occurrence of PFOL was higher in IVD (61.5%) compared to ALT (5.3%), and Control groups (10.5%; P < 0.01). The AFR was lower in IVD (53.8%) than in ALT (88.2%) and Control (94.7%; P ≤ 0.05). The total number of piglets born was not affected by hormonal treatments in either experiment. Estrous expression was delayed in gilts treated with altrenogest or IVD-MPA. However, the reproductive performance of IVD-gilts was compromised, which was not circumvented by IVD replacement in the middle of treatment. Therefore, further studies are necessary to understand MPA pharmacodynamics and investigate alternative devices for a steady release of progestogens in gilts.