Impact of housing nursery pigs according to body weight on the onset of feed intake, aggressive behavior, and growth performance.

Housing nursery pigs according to body weight is an observed common practice in production systems and, supposedly, improves growth performance and reduces body weight (BW) variation. This 42-day study evaluated the effects of housing nursery pigs according to BW on performance, onset of feed intake, and aggressive behavior. A total of 504 pigs were ranked by BW at weaning and categorized into three groups of 168 pigs each: light, medium, and heavy. Pigs were randomly distributed to unsorted pens (Unsorted) containing 6 pigs of each weight group and sorted pens with 18 pigs from just one group per pen (Sorted). From weaning to day 3, pigs were fed a diet containing 1% iron oxide dye and rectal swabs presenting red coloration were evaluated to assess feed intake onset. Eight pens were video recorded to evaluate aggressive behavior. Sorted-Heavy pigs delayed the onset of feed intake (P ≤ 0.011) and presented more aggressive behaviors than Sorted-Light and Sorted-Medium pigs (P ≤ 0.036). In Unsorted, onset of feed intake showed no differences between weight categories. Also, no differences were observed for aggressive behavior between Sorted and Unsorted. Final BW showed no differences between Sorted and Unsorted pigs. The within-pen weight coefficient variation (CV) was slightly different (P = 0.042) between Sorted and Unsorted pigs (13.3 and 15.6%, respectively), at the end of the study. Thus, sorting nursery pigs by BW did not improve growth performance and also, induce a lag of post-weaning feed intake onset and increased fights in Heavy pigs.

Testicular parameters and spermatogenesis in different birthweight boars.

The present study investigated the effect of birthweight on testicular development and spermatogenesis in boars. Twenty-four pairs of littermate boars were selected: one piglet with the highest birthweight (HW) and the other with the lowest birthweight (LW) within the litter. Two subsets of 12 pairs of male littermates from each birthweight group were obtained after selection: one subset was orchiectomised at 8 days and the other at 8 months of age. HW boars had higher body and testicular weights at both ages (P<0.05). Testosterone concentrations and the relative expression of 17α-hydroxylase in the testis were similar between birthweight groups. Birthweight affected somatic and germ cell numbers in the neonatal testis, which were higher in HW boars (P<0.05). Moreover, a significant reduction in the number of pachytene spermatocytes and round spermatids was observed in LW boars (P<0.05) at 8 months of age, which caused a decrease in the total number of elongated spermatids and daily sperm production (P<0.05). Hence, HW boars have the potential to produce more spermatozoa and consequently more semen doses per ejaculate, and would be very valuable to an industry that relies on AI.

Fixed-time post-cervical artificial insemination in weaned sows following buserelin use combined with/without eCG.

Fixed-time post-cervical artificial insemination (FTAI) drastically reduces labour requirements and increases the use of boars with higher genetic merit. This study evaluated the efficiency of eCG administration combined with/without the GnRH agonist buserelin for the induction and synchronization of ovulation in weaned sows submitted to FTAI. The sows were allocated into three groups. In the control group, the first artificial insemination was performed at the onset of oestrus and repeated every 24 hr. In the eCG+GnRH group, sows received 600 IU eCG at weaning and buserelin (10 µg) after 86-89 hr of eCG, and in the GnRH group, sows received only buserelin after 86-89 hr of weaning. The hormone-treated sows received a single FTAI after 30-33 hr of buserelin application. All the sows were inseminated with homospermic doses (1.5 × 109  sperm cells/50 ml). The interval between weaning and ovulation was shorter (p < .05) in the eCG+GnRH (133.3 hr) and GnRH (135.9 hr) groups than the control (141.5 hr) group. In the eCG+GnRH group, the sows ovulated earlier (p < .05) than those in the GnRH group (44.5 vs. 48.2 hr after buserelin administration). The reproductive performance of GnRH sows was not compromised when only sows exhibiting oestrus at the time of insemination were considered, but lower farrowing rate and smaller litter size were observed in eCG+GnRH sows. The reproductive performance of eCG+GnRH sows was primarily compromised because the insemination was performed outside the optimal time relative to ovulation; therefore, it is advisable to inseminate them before 116-122 hr after weaning.

Colostrum yield and litter performance in multiparous sows subjected to farrowing induction.

The consumption of colostrum at a low level can compromise the survival and growth of piglets. Therefore, this study aimed to evaluate the effect of farrowing induction on colostrum yield, IgG concentration and the survival and performance of piglets until the weaning. Sows of parity 3 to 7 were assigned into two groups: Control (n = 48), sows with spontaneous farrowing; and induction (n = 48), sows induced to farrow on day 114 of gestation with a PGF2 analogue. Colostrum and blood samples were collected from the sows, at farrowing and 24 hr later. Blood samples from the piglets were collected at 24 hr after birth. The performance of the piglets was evaluated in a subsample of 28 litters from each group. All piglets were weighed at 7, 14 and 20 days of age. The farrowing length, the number of piglets born alive, stillborn piglets, weight at birth, litter weight at birth and colostrum yield were not significantly affected (p > .05) by farrowing induction. There was no difference between the groups (p > .05) in the percentage of sows with obstetric interventions. Serum IgG concentration, in both sows and piglets, and colostrum IgG concentration were similar between the groups (p > .05). Furthermore, survival rate, piglet weight and litter weight at 7, 14 and 20 days of age were also similar between the groups (p > .05). Therefore, it can be concluded that the farrowing induction performed on day 114 of gestation does not affect the colostrum yield, the IgG concentration in colostrum and serum of piglets, and the litter performance until the weaning.

New Artificial Insemination Technologies for Swine.

Better efficiency in swine artificial insemination (AI) is accomplished by reducing the necessary number of sperm cells and achieving high reproductive performance. Some strategies have been developed for use under field conditions, such as the site of sperm deposition (post-cervical AI), a single AI with control of oestrus and ovulation (fixed-time AI), and the better use of high genetic merit boars, to spread their genes as much as possible. To apply these technologies, it is important to understand some anatomical limits, physiological aspects and farm requirements. In this review, we point out some strategies to achieve higher efficiency on the use of sperm for AI technology application in swine species.

Use of porcine luteinizing hormone at oestrous onset in a protocol for fixed-time artificial insemination in gilts.

The aim of this study was to evaluate the effect of porcine luteinizing hormone (pLH) given at oestrous onset in gilts, by different routes and doses, on the interval between onset of oestrus and ovulation (IOEO) and reproductive performance using a single fixed-time artificial insemination (FTAI). A total of 153 gilts were submitted to oestrous detection at 8-h intervals and assigned to three groups: control - without hormone application and inseminated at 0, 24 and 48 h after oestrous onset; VS2.5FTAI - 2.5 mg pLH by the vulvar submucosal route at oestrous onset and a single FTAI 16 h later; IM5FTAI - 5 mg pLH by the intramuscular route at oestrous onset and a single FTAI 16 h later. More VS2.5FTAI gilts (47.1%; p < 0.05) ovulated within 24 h after oestrous onset than control gilts (25.5%) whereas IM5FTAI gilts had an intermediate percentage (31.4%; p > 0.05). The IOEO tended to be shorter (p = 0.06) in VS2.5FTAI (30.2 ± 1.4 h) than in control (34.7 ± 1.4 h) gilts, but there was no difference (p > 0.05) between control and IM5FTAI (32.8 ± 1.4 h) gilts. Farrowing rate was not different (p > 0.05) among treatments. Total born piglets (TB) was lower (p < 0.05) in VS2.5FTAI (12.3 ± 0.4) than in control gilts (14.1 ± 0.4), whereas intermediate TB was observed in IM5FTAI gilts (13.3 ± 0.4). Due to the advancement of ovulation, reduction of the hormonal dose and the ease of application, the vulvar submucosal route would be the best option for FTAI protocols, but their negative impact on litter size remains to be elucidated. Taking into account the good fertility results obtained in IM5FTAI gilts whose ovulation was not advanced, the possibility of a single FTAI without any hormonal treatment should be further investigated, to establish reliable FTAI protocols for gilts.

The post-cervical insemination does not impair the reproductive performance of primiparous sows.

The study evaluated the reproductive performance of primiparous sows submitted to post-cervical insemination (PCAI) compared with cervical artificial insemination (CAI). Difficulty with catheter introduction, the occurrence of bleeding or semen backflow during insemination, and volume and sperm cell backflow up to 60 min after insemination were also evaluated. Sows were homogenously distributed, according to body weight loss in lactation, lactation length, weaned piglets, weaning-to-oestrus interval and total born in previous farrowing, in two treatments: PCAI (n = 165) with 1.5 × 10(9) sperm cells in 45 ml (2.4 ± 0.04 doses per sow) and CAI (n = 165) with 3 × 10(9) sperm cells in 90 ml (2.5 ± 0.04 doses per sow). During PCAI, sows were inseminated in the absence of boars. Transabdominal real-time ultrasonography was performed at oestrus onset, immediately before the first insemination and at 24 h after last insemination. There was no difference (P > 0.05) between treatments in farrowing rate (91.5% × 89.1%) and litter size (12.5 × 11.9 piglets born, respectively for PCAI and CAI sows). Successful passage of the intrauterine catheter in all the inseminations was possible in 86.8% (165/190) of sows initially allocated to PCAI treatment. Difficulty of introducing the catheter in at least one insemination did not affect the reproductive performance of PCAI sows (P > 0.05). Bleeding during insemination did not affect (P > 0.05) the farrowing rate in both treatments, but litter size was reduced in CAI and PCAI sows (P ≤ 0.06). Percentage of spermatozoa present in backflow within 1 h after insemination was greater in CAI than PCAI sows (P < 0.01). More than 85% of primiparous sows can be successfully post-cervical inseminated with doses containing 1.5 × 10(9) sperm cells in the absence of the boar during insemination without impairing the reproductive performance.

Prostaglandin F2α treatment does not hasten ovulation in weaned sows.

This study evaluated the efficiency of prostaglandin F2α (PGF) to hasten ovulation in weaned sows. In experiment I, weaned sows detected in estrus (0 h) received: no hormone (Control; n = 56); 0.5 mg PGF IM at 0 h and 2 h (PGF0; n = 56); or 0.5 mg PGF IM at 24 h and 26 h (PGF24; n = 55). In experiment II, weaned sows that did not express estrus signs until 72 h after weaning (0 h) were assigned to: no hormone (Control; n = 45); 10 µg buserelin acetate IM at 0 h (Buserelin; n = 43); 0.5 mg PGF IM at 34 h and 36 h (PGF; n = 44); or 10 µg buserelin acetate IM at 0 h plus 0.5 mg PGF IM at 34 h and 36 h (Buserelin + PGF; n = 45). In experiment I, no effect of PGF on the interval treatment onset to ovulation was observed (P > 0.05), and no treatment effect was observed on the relative or cumulative proportion of females that ovulated post-treatment onset (P > 0.05). In experiment II, treatment onset to ovulation interval was shorter for Buserelin group than for PGF group (P < 0.05), and a higher cumulative percentage of Buserelin treated sows ovulated up to 48 h compared to PGF and Control groups (P < 0.01), with no differences from Buserelin + PGF. Treatments did not affect total number of piglets born in both experiments (P > 0.05). In conclusion, PGF did not hasten ovulation timing or affect litter size in weaned sows.

Altrenogest treatment associated with a farrowing induction protocol to avoid early parturition in sows.

This study investigated the effect of altrenogest treatment on the farrowing development of sows, and birth weight (BW) and piglet survival until the third day of life. Three control groups were used: (i) sows that farrowed spontaneously before 114 day of gestation (CONT <114); (ii) sows that spontaneously farrowed at ≥114 day of gestation (CONT ≥114); (iii) sows that farrowed at ≥114 day with cloprostenol treatment (CONTCLOPR). Other sows were treated with altrenogest (Regumate(®) ) for 3 days (days 111, 112 and 113 of gestation): one group gave birth spontaneously (ALT) and the other group received altrenogest until day 113 and cloprostenol on day 114 (ALTCLOPR). There were no differences (p > 0.05) in farrowing duration, BW, coefficient of variation (CV) of BW, stillborn piglets, mummified foetuses, percentage of light piglets and survival until Day 3 between sows with and without cloprostenol treatment, in both control (CONT ≥114 vs CONTCLOPR) and altrenogest-treated sows (ALT vs ALTCLOPR). Further comparisons were performed taking into account three groups: sows with early delivery (CONT <114 - farrowing before 114 days of gestation; n = 56), sows with longer gestation (CONT ≥114 - with and without cloprostenol treatment sows; n = 103) and ALT sows (with and without cloprostenol treatment; n = 105). Gestation length of CONT ≥114 and ALT sows was similar (p > 0.05), but higher than in CONT <114 sows. There were no differences (p > 0.05) between groups in farrowing duration, CV of BW, and percentages of stillborn piglets and mummified foetuses. Sows of CONT <114 group had a larger litter size and a lower BW than sows of the other two groups (p < 0.05). Sows of CONT <114 group had a higher percentage of lighter piglets and a lower piglet survival rate (p < 0.05) than ALT sows. In conclusion, altrenogest treatment proved to be an efficient method to avoid early parturition in 3-5 parity sows resulting in heavier piglets at birth.

Multivariate analyses for determining the association of field porcine fertility with sperm motion traits analysed by computer-assisted semen analysis and with sperm morphology.

This study investigates the association of semen traits with boar fertility. The fertility outcome (farrowing rate - FR and total piglets born - TB) of 14 boars was obtained from a field trial conducted during 10 week of breeding period on a commercial farm using multiparous sows (n = 948) through single-sire mating with 2 × 10(9) motile sperm cells per artificial insemination (AI) dose. Sperm motion parameters, evaluated with computer-assisted semen analysis system in raw and stored semen at 17°C for 240 h, in addition to morphological sperm defects, measured on the collection day, were included in the analysis to determine which semen traits were important to discriminate the fertility potential of ejaculates from these boars. The data underwent multivariate cluster, canonical and discriminant analyses. Four clusters of boars were formed based on fertility outcome. One boar, with the lowest FR and TB values (89.7% and 11.98), and two boars, with the highest FR and TB values (97.8% and 14.16), were placed in different clusters. The other boars were separated in two distinct clusters (four and seven boars), including boars with intermediate TB (12.64 and 13.22) but divergent values for FR (95.9% vs 91.8%). Semen traits with higher discriminatory power included total motility, progressive motility, amplitude of lateral head displacement and cytoplasmatic droplets. Through multivariate discriminant analysis, more than 80% of the 140 ejaculates were correctly classified into their own group, showing that this analysis may be an efficient statistical tool to improve the discrimination of potential fertility of boars. Nevertheless, the validation of the relationship between fertility and semen traits using this statistical approach needs to be performed on a larger number of farms and with a greater number of boars.

Effects of breeding at the second oestrus or after post-weaning hormonal treatment with altrenogest on subsequent reproductive performance of primiparous sows.

This study investigated the effects of breeding at the second oestrus after weaning or after feeding an orally active progestagen (altrenogest) on the subsequent reproductive performance of primiparous sows. After 3 weeks of lactation, 663 weaned sows of two genotypes were allocated into three groups: G1--breeding at the first oestrus after weaning; G2--breeding at the second oestrus after weaning and G3--treatment with altrenogest for 5 days after weaning and breeding at the first oestrus after the end of the treatment. Body weight at breeding was lower in G1 and G3 than in G2 sows (p < 0.05). The interval to show oestrus was similar for G1 and G2 groups (p > 0.05) but higher (p < 0.05) than that observed in G3 group. Within genotype A, percentages of females in oestrus within 10 days were not different (p > 0.05) among groups, whereas in genotype B, more G1 and G2 sows (p < 0.05) showed oestrus than G3 sows. In both genotypes, lower farrowing rates were observed in G3 than in G1 and G2 sows (p < 0.05) and a greater litter size (p < 0.05) was observed in G2 sows. In genotype A, the number of total born piglets was similar for G1 and G3 groups (p > 0.05), whereas in genotype B, G1 sows had a greater litter size than G3 sows (p < 0.05). Body weight at weaning and at breeding was similar (p > 0.05) between farrowed and non-farrowed sows in all groups. Reproductive performance is not improved in primiparous sows treated with altrenogest during 5 days after weaning. The reproductive performance of genotype B sows is compromised in Control and Altrenogest-treated sows but not in those bred at the second oestrus after mating. Breeding at the second oestrus after weaning allows primiparous sows to gain weight between weaning and service, and increases their farrowing rate and subsequent litter size.

Effects of different amounts and type of diet during weaning-to-estrus interval on reproductive performance of primiparous and multiparous sows.

During weaning-to-estrus interval (WEI), the sows are usually fed with high feed level to improve the reproductive performance. However, the WEI has been reduced over the years which may reduce the impact of feed level on performance in the modern genetic lines. The aim of this study was to evaluate the effect of two feeding levels (moderate feeding level (MFL): 2.7 kg/day and high feeding level (HFL): 4.3 kg/day) and two diet types (gestation: 13.67 MJ/kg of metabolizable energy (ME) and 0.62% of standard ileal digestible lysine (SID Lys) and lactation: 14.34 MJ ME/kg and 1.20% of SID Lys) offered during the WEI on reproductive performance. In total, 19.0% of sows were excluded from the analysis due to feed intake below 75% (9.6% and 28.5% in MFL and HFL groups, respectively), remaining 254 primiparous and 806 multiparous sows. Follicular size and change in BW were measured in subsamples of 180 and 227 females, respectively. Data were analyzed considering the sow as the experimental unit. Feeding level, diet type, parity and their interactions were included as fixed effects, whereas the day of weaning was considered as a random effect. The feed intake of MFL and HFL groups averaged 2.5 ± 0.02 and 3.8 ± 0.02 kg/day, respectively. There was an interaction between feeding level and parity for daily feed intake. Within HFL, multiparous sows consumed 181 g/day more than primiparous sows (P < 0.01), but no difference was observed within MFL (P > 0.05). Both primiparous and multiparous sows lost proportionally less weight when fed HFL than MFL gestation diet during WEI. The percentage of weight loss was lower in HFL than in the MFL group in multiparous sows fed the lactation diet. The WEI was not affected by feeding level, diet type or its interaction (P > 0.05), but it was longer in primiparous than in multiparous sows (P = 0.001). There was no effect of feeding level, diet type, parity or their interactions on anestrus and farrowing rates. Multiparous sows showed greater follicular size, and greater numbers of total born and born alive piglets in the subsequent cycle than primiparous sows (P < 0.05). In conclusion, feeding weaned primiparous and multiparous sows with 4.3 kg/day of a gestation (58.78 MJ ME and 26.66 g SID Lys) or a lactation diet (61.66 MJ ME and 51.60 g SID Lys) does not improve follicular size and reproductive performance in the subsequent cycle.

Reproductive performance of gilts with similar age but with different growth rate at the onset of puberty stimulation.

The aim of this study was to evaluate the reproductive performance of gilts that had a similar age but different weights at the onset of puberty stimulation by boar exposure at 144 days. Gilts were divided into two groups according to their lifetime growth rate from birth to approximately 144 days of age. Mean growth rates at this moment were 577 and 724 g/day for group 1 (G1; n = 58) and group 2 (G2; n = 58), respectively. After selection, gilts were weighed at approximately 155, 165 and 175 days of age, on the insemination day and at slaughter. Gilts were inseminated, on average, at 193 days of age and were slaughtered 32 days after insemination, when the number of corpora lutea and embryos were recorded. Higher growth rate gilts (G2) reached puberty earlier (155.3 vs 164.1 days; p < 0.01). More gilts of G2 group attained puberty by 190 days of age (p = 0.004) than G1 gilts (95%; 55/58 vs 76%; 44/58). The anoestrous rate, until 60 days after the onset of boar exposure was higher (p < 0.01) in G1 (19.0%; 11/58) than in G2 (3.4%; 2/58) group. However, there were no differences in the pregnancy rate (90.7 vs 94.5), ovulation rate (15.9 vs 16.5), total embryos (12.9 vs 11.7), viable embryos (12.0 vs 11.1) and embryo survival (73.7% vs 68.5%), between G1 gilts and G2 gilts, respectively (p > 0.05). High growth rate gilts attain puberty earlier and have a lower anoestrous rate than low growth rate gilts.

Post-cervical artificial insemination in porcine: The technique that came to stay.

The porcine industry is of great importance worldwide, and so any technological innovation in one or more of the associated production areas is of interest for meat production. Among such innovations in the reproduction area, post-cervical or intrauterine artificial insemination (PCAI) has emerged as a new approach in artificial insemination (AI). PCAI is gradually replacing traditional cervical insemination (CAI), particularly in countries with intensive pig production industries. This type of insemination, which deposits the semen in the body of the uterus (as opposed to traditional cervical deposition), is increasingly used in the field due to its simplicity and the numerous advantages that it provides at production level (e.g. reduced number of sperm, less time required to perform insemination and faster genetic improvement) and, consequently, from an economic point of view. In addition, since its inception, PCAI has been combined with other reproductive biotechnologies, such as the use of frozen-thawed sperm, fixed-time AI or sperm-mediated gene transfer. However, despite its wide acceptance and application, new approaches for increasing the efficiency of PCAI are constantly being sought, such as the adjustment and standardization in sperm numbers, the conservation of the PCAI semen dose, its association with other biotechnologies (sex-sorted sperm) or its efficacy in young (nulliparous and primiparous) females.

Ovulation and fertility responses for sows receiving once daily boar exposure after weaning and OvuGel® followed by a single fixed time post cervical artificial insemination.

Boar exposure is used to stimulate follicle development and estrus in sows after weaning and also to improve semen uptake and sperm transport with insemination. However, the need and value of boar exposure is uncertain when ovulation induction is used. These studies were designed to determine the effect of daily boar exposure after weaning when used with ovulation induction and fixed time post-cervical artificial insemination (PCAI). In experiment 1, sows were weaned into stalls and assigned to receive 3 min of daily fenceline boar exposure (BE, n = 7) or no boar exposure (NBE, n = 8). All sows received OvuGel at 96 h after weaning and BE or NBE 30 min prior to a single PCAI 24 h after OvuGel. Ovaries were assessed daily for follicle size from weaning until ovulation. Cervical contractions were measured 30 min following BE or NBE and before PCAI, while uterine contractions were measured for 1 h following PCAI. In experiment 2, weaned sows (n = 244) were assigned by parity to receive once daily BE for 1.5 min each day or NBE. OvuGel, PCAI and ultrasound methods were performed similarly as in experiment 1. Results from experiment 1 indicated BE did not significantly influence follicle size or measures of fertility. However, BE did increase the frequency of cervical contractions (P < 0.05), but with no effect on the uterus. Results from experiment 2 indicated BE had no effect on catheter passage for PCAI but did increase the proportion of sows ovulating within 48 h after OvuGel (77.7 vs 67.5%, P = 0.05), and tended (P = 0.10) to increase the proportion of sows inseminated 24 h before ovulation (70.3 vs. 61.0%). However, BE had no effect on adjusted farrowing rate (84.4 vs. 77.4%) or total pigs born (13.2 vs. 12.5) for BE and NBE, respectively. There were treatment and parity interactions for follicle size at time of OvuGel and at time of PCAI (P < 0.05) with BE minimizing parity effects on follicle size. Parity effects were also evident on farrowing rate and litter size when inseminations occurred >24 h from ovulation but not when inseminations occurred ≤24 h before ovulation. The results indicate that boar exposure for only minutes each day after weaning had beneficial effects for improving follicle development, ovulation induction, and AI timing, most notably in parity 1 sows, but had no beneficial or detrimental effects on the ability to perform PCAI.

Single fixed-time artificial insemination in gilts and weaned sows using pLH at estrus onset administered through vulvar submucosal route.

This study evaluated the use of a single fixed-time artificial insemination (FTAI) in gilts and weaned sows using 2.5 mg of porcine luteinizing hormone (pLH) administered through vulvar submucosal route, at the onset of estrus. In experiment 1 (Exp.1), 318 pubertal gilts were assigned to two groups: control-G-no hormonal application and artificial inseminations (AIs) at 12, 36, and 60 hours after the onset of estrus if they were still in standing estrus; and FTAI-G-use of pLH at the onset of estrus and a single FTAI 12 hours later. In experiment 2 (Exp. 2), 309 weaned sows were assigned to three groups: Control-S-no hormone application and AIs at 0, 24, and 48 hours after the onset of estrus if they were still in standing estrus; FTAI-NH-no hormone application and a single FTAI at 24 hours after the onset of estrus, and FTAI-pLH-use of pLH at the onset of estrus and a single FTAI 24 hours later. Transabdominal real time B-mode ultrasonography was performed to determine whether the insemination had been performed within 24 hours before ovulation, considered as the optimal interval. In Exp. 1, ultrasound evaluation (12-hour intervals) was carried out to determine the interval between the onset of estrus and ovulation. In both experiments, 2 × 10(9) sperm cells in 80 mL were used to perform cervical and postcervical deposition of semen in gilts and sows, respectively. Compared with control-G, FTAI-G gilts had shorter (P < 0.05) duration of estrus (57.7 vs. 61.2 hours) and interval between the onset of estrus and ovulation (36.3 vs. 42.3 hours). The adjusted farrowing rate (AFR) was lower (P < 0.05) in FTAI-G (86.0%) compared with control-G (93.5%), but total piglets born (TPB) did not differ between these groups (12.3 vs. 12.5 piglets). Within the FTAI-G group, the AFR was lower (P < 0.05) in the presence (50.0%) than in the absence (94.9%) of semen backflow during AI. Also in the FTAI-G group, the insemination outside the optimal interval reduced (P < 0.05) the TPB (10.5 vs. 12.9 piglets) in comparison with gilts inseminated within the optimal interval. In Exp. 2, there were no differences in the AFR (Control-S: 94.1%; FTAI-NH: 86.1%; FTAI-pLH: 88.0%) and TPB (Control-S: 12.8; FTAI-NH: 12.7, and FTAI-pLH: 12.0 piglets) among treatments. The presence of semen backflow reduced (P < 0.05) the TPB in FTAI-pLH and FTAI-NH sows. In the FTAI-pLH, a single insemination performed too late relative to ovulation reduced the AFR (P < 0.05) compared with sows inseminated within the optimal interval. In conclusion, 2.5-mg pLH applied at the vulvar submucosa at the onset of estrus advances the ovulation in gilts, but a single FTAI performed 12 hours later reduces the farrowing rate. A single FTAI performed at 24 hours after the onset of estrus in weaned sows does not affect their reproductive performance, regardless of pLH application.

The initial fertilizing capacity of longerm-stored liquid boar semen following pre- and postovulatory insemination.

In pigs, high variation is seen in the duration of estrus and in the time of ovulation. This is one of a wide range of factors not related to semen quality, which possibly influences the results of field insemination trials. Experiment 1 (n=81 gilts) was performed to determine the influence of the time of ovulation on the fertilizing capacity of liquid boar semen stored up to 118 h. The objective of Experiment 2 (n=102 gilts) was to study the fertilizing potential of semen stored up to 120 h in 2 different extenders, Androhep and Beltsville Thawing Solution (BTS), by means of postovulatory AI. Inseminations were performed 0 to 4 h after ovulation in order to standardize the trial conditions. Fertilization rates based on Day-2 to Day-4 embryos, and the number of accessory spermatozoa per zona pellucida did not differ between semen stored for 0 to 48 and 48 to 87 h in gilts ovulating within 12 after insemination (Experiment 1). Gilts with an interval of 12 to 24 h between AI and ovulation had lower fertility results using semen stored for more than 48 h. A further decrease was observed when semen storage exceeded 87 h in those gilts ovulating later than 24 h after insemination. The time of ovulation has to be considered as being a major factor of variation in the fertility results of AI trials. In Experiment 2, fertilization rates and numbers of accessory spermatozoa decreased between semen stored for 0 to 24 and 24 to 48 h in BTS, and between semen stored for 0 to 24 and 48 to 72 h in Androhep. Significant differences in fertility between diluents were seen only when using semen stored for more than 96 h, with semen extended with Androhep giving the higher results. The results indicate that the decrease in fertilizing capacity due to in vitro aging of spermatozoa cannot be prevented even during the first days of storage.

Fixed-time post-cervical artificial insemination in sows receiving porcine luteinising hormone at oestrus onset.

Fixed-time post-cervical artificial insemination (FTPCAI) allows a wider use of high indexing boars and a considerable reduction in labour requirements in swine production. The aim of this study was to evaluate fixed-time artificial insemination (FTAI) efficiency using different artificial insemination protocols and porcine luteinising hormone (pLH) to induce ovulation. A total of 597 weaned sows in which oestrus detection was performed once daily (08:00 am) was allocated to three groups: FTPCAI1 (n=199) - sows received a 5-mg (4 ml) intramuscular injection of pLH at oestrus onset, and were inseminated 24h later; FTPCAI2 (n=199) - sows received 5mg of pLH and were inseminated at oestrus onset (0 h) and 24h after; and MultPCAI (n=199) - sows did not receive pLH, and the first AI was performed at oestrus onset (0 h) and repeated every 24h during oestrus. Homospermic doses (1.5 × 10(9) total sperm cells/50 ml) were used in post-cervical artificial insemination (PCAI) in all the treatments. Hormonal treatment did not affect (P>0.05) the interval between oestrus onset and ovulation (overall 32.4h) and there were no differences (P>0.05) in farrowing rate (overall 91.6%) or litter size (overall 12.6 piglets born) among treatments. In sows treated with pLH at oestrus onset, a single PCAI with 1.5 billion sperm cells did not compromise reproductive performance compared with a double PCAI at 24h intervals.

Effect of birth weight and colostrum intake on mortality and performance of piglets after cross-fostering in sows of different parities.

The objective of this study was to evaluate the effect of colostrum intake on mortality and growth performance of piglets until 42 days of age, taking into account the birth weight, and parity order of sows. Colostrum intake from birth to 24h after birth was estimated in 300 piglets each from primiparous and multiparous sows. The piglets were cross-fostered in 25 primiparous and 25 multiparous sows at 25.9±0.09 h after farrowing. The concentration of serum immunoglobulin G (IgG) was determined in the sows after the end of farrowing and in the piglets before cross-fostering (24h after farrowing), at 10 and 20 days of age. For high birth weight piglets (HBW - >1.3-1.7 kg) the probability of death was low regardless of their colostrum intake. Intermediate birth weight (IBW - >1.2-1.3 kg) and low birth weight (LBW - 1.1-1.2 kg) piglets had the same probability of death compared to HBW piglets, when colostrum intake reached 200 and 250 g, respectively. The probability of low performance (<9.5 kg) was lower in HBW than in LBW and IBW piglets, regardless of colostrum intake. HBW piglets had higher weight at 14, 20, 28 and 42 days of age (P<0.05) than LBW piglets, and higher weight than IBW piglets at 28 and 42 days. Colostrum intake >250 g increased (P<0.05) the weight of piglets at 28 and 42 days of age, regardless of their birth weight. Piglets from primiparous biological dams consumed less colostrum (P<0.003) than piglets from multiparous dams, but their serum IgG concentrations at 24h after birth and their performance were similar (P>0.05). Piglets suckled by primiparous foster sows showed lower weight (P<0.05) at 20, 28 and 42 days than piglets suckled by multiparous sows. Piglets that died before 42 days of age had lower (P<0.05) birth weight, colostrum intake and serum IgG at 24 h after birth compared to surviving piglets, and lower values were also observed in piglets with low performance compared to high (>9.5 kg) performance piglets. There were no differences in serum IgG concentrations at 10 and 20 days of age (P>0.05) between high and low performance piglets. In conclusion, both colostrum intake and birth weight are important for survival and growth of suckling piglets. LBW and IBW piglets are more dependent on colostrum intake than HBW piglets to assure higher survival and better development up to 42 days of age. Piglets suckled by multiparous sows have better development than those suckled by primiparous sows.

Use of testicular tone and echogenicity in identifying boars with low sperm quality / Uso de tônus e ecogenicidade testiculares na identificação de reprodutores suínos com baixa qualidade espermática

This study aimed to evaluate the use of some testicular traits to identify boars with low sperm morphological quality. The consistency (scores from 1 to 5), tone with tonometry (mm), parenchyma echogenicity and heterogeneity with ultrasound (pixel) were assessed in 402 mature boars (18.5 months on average). Sperm abnormality thresholds (≤ 25% of total sperm abnormalities, ≤ 5% of heads, acrosome, neck or midpiece defects, ≤ 10% tail defects, and 15% cytoplasmic droplets) were used to classify boars as approved or disapproved. Three classes of testicular traits were formed (extremely low and high values, approximately 15% each, were kept in separated classes). When the traits were individually evaluated, fewer boars were approved if the echogenicity or heterogeneity were high, or if the tone was rigid. When evaluated in combination, the interaction between heterogeneity and tone, and between heterogeneity and echogenicity were significant. The high heterogeneity combined with soft tone or with hypo-echogenicity resulted in lower approval of boars. Tonometry and ultrasonography have a moderate potential to be included in breeding soundness examination of boars. When combined, they provide more reliable information about the impact of testicular parenchymal alterations on morphology of sperm cells.(AU)

O estudo objetivou avaliar o uso de características testiculares para identificar reprodutores com baixa qualidade de morfologia espermática. A consistência (escore de 1 a 5), o tônus por tonometria (mm), a ecogenicidade e a heterogeneidade do parênquima testicular por ultrassonografia (pixel) foram avaliados em 402 machos suínos maduros (18,5 meses, em média). Limiares máximos de anormalidades espermáticas (≤ 25% de defeitos totais, ≤ 5% de defeitos de cabeça, acrossoma, colo e peça intermediária, ≤ 10% de defeitos de cauda e 15% de gota citoplasmática) foram utilizados para classificar os machos como aprovados ou reprovados. Três classes de características testiculares foram formadas (valores extremamente baixos e altos, aproximadamente 15% em cada, foram mantidos em classes separadas). Quando as características testiculares foram avaliadas individualmente, menos machos foram aprovados se a ecogenicidade ou a heterogeneidade foram altas, ou se o tônus era rígido. Quando avaliadas em combinação, a interação entre heterogeneidade e tônus e a interação entre heterogeneidade e ecogenicidade foram significativas. A alta heterogeneidade combinada com testículos flácidos ou com testículos hipoecogênicos resultou em menor aprovação de cachaços. A tonometria e a ultrassonografia possuem potencial moderado para serem incluídas no exame andrológico de cachaços. Quando combinadas, as técnicas fornecem uma informação mais consistente do impacto das alterações do parênquima testicular na morfologia das células espermáticas.(AU)