Use of testicular tone and echogenicity in identifying boars with low sperm quality

ABSTRACT 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.

Performance of low birth-weight piglets upon protein-energy and/or colostrum supplementation

ABSTRACT The study aimed to investigate the effect of oral protein-energy supplement (OPES) and/or extra colostrum within the first few hours of life on the survival and growth performance of low birth-weight piglets during the suckling period. Based upon nutritional strategy, low-birth-weight piglets (804−1309g) were randomly allocated into four groups: C0S0 (control group, n= 300) - no supplementation; C1S0 (n= 299) - supplementation with 50mL of a colostrum pool through an orogastric tube; C0S1 (n= 298) - oral supplementation with 8mL oral OPES; C1S1 (n= 297) - supplementation with both 50mL of colostrum and 8mL of OPES. The piglets’ body weight was monitored at birth, 24h after birth, on day 7, day 14 and day 20 post-partum. Both colostrum and protein-energy supplementations did not affect (P>0.05) colostrum intake (253.6g; 259.4g; 259.4g; 263.8g for C0S0, C1S0, C0S1, C1S1, respectively), weight gain during the first 24h (62.6g; 68.3g; 67.1g and 69.8g for C0S0, C1S0, C0S1, C1S1, respectively) and pre-weaning mortality (11.3%, 11.4%, 12.4% and 9.4% for C0S0, C1S0, C0S1, C1S1, respectively). Administration of OPES increased (P= 0.032) the average daily weight gain from birth till weaning (189.1 vs. 182.3g) and tended to increase the weight of the piglets (P= 0.060) at weaning (4893.1 vs. 4746.4g for OPES and no OPES, respectively). In conclusion, nutritional manipulation does not affect colostrum intake and pre-weaning mortality of low birth-weight piglets. However, body weight gain during the suckling period and the weight at weaning were observed to be marginally improved by administration of OPES.

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.

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.

Factors influencing colostrum yield by sows

ABSTRACT An adequate colostrum intake, in order to ensure the survival and weight gain of piglets, depends on the sow's ability to produce enough colostrum for the whole litter. The aim of this study was to evaluate factors involved in colostrum yield (CY) variability related to the sow, the litter and the farrowing process. The experiment was conducted with 96 Camborough 25(r) sows of parities one to seven, whose farrowing was spontaneous. Colostrum production of each sow was estimated by summing up the colostrum intake of each piglet in the litter, estimated by an equation that takes into account the birth weight and weight gain during the first 24h of life. The multiple regression model explained 28% of variation in CY, with 24% and 4% respectively of variation being explained by the litter birth weight and the width of the first mammary glands. Litter birth weight was positively correlated with the number of total born (r= 0.73) and born alive piglets (r= 0.83). When categorised into two groups of colostrum yield (LOWCY; ≤3.4kg; n= 46 vs HIGHCY; >3.4kg; n= 50), LOWCY sows had fewer total born and born alive piglets and lighter litters (P<0.05). The logistic regression analysis showed that sows from parities 1, 2 and >3 had greater odds (P≤0.05) of belonging to the LOWCY group than parity 3 sows. Sows with two or more obstetrical interventions had higher odds (P<0.05) of belonging to the LOWCY group than sows without interventions during farrowing. The higher colostrum yield observed in sows of parity 3 and sows with less than two obstetrical interventions during farrowing was associated with a greater number of nursed piglets. This study showed that total birth weight of born alive piglets is the most important factor involved in colostrum yield variability, indirectly representing the number of piglets nursed by the sow.

Effect of body development from first insemination to first weaning on performance and culling until the third farrowing of Landrace x Large White swine females

The aim of this study was to verify the association of sow body weight development until the 1st weaning with reproductive performance, piglet production and culling rate until the 3rd farrowing in 196 primiparous sows using logistic regression models. Each 10kg increase in weight gain in the 1stpregnancy (OR= 0.63), weight at 1st farrowing (OR= 0.70), weight at the 1st weaning (OR= 0.73) or weight gain from the 1startificial insemination (AI) to the 1st weaning (OR= 0.67) decreased the percentage of primiparous sows with long weaning-to-oestrus interval - WOI (>5 days). An increasing lactation length and an increase in the number of weaned piglets were responsible for respectively decreasing (OR= 0.77-0.80, per day of lactation) and increasing (OR= 1.52-1.59, per piglet weaned) the percentage of sows with long WOI. Sows with <159.5kg at weaning had higher odds of non-farrowing (NFR) compared to sows with >170kg (OR= 4.73). Sows with <17.5kg of gain from the 1st AI to the 1st weaning had higher odds (OR= 4.88) of NFR than sows gaining >30kg. Each additional lactation day decreased the NFR (OR= 0.74). Females weighing <139kg at the 1st AI had higher percentages of small numbers of total born in the second parity (STB2, OR= 2.00) and over three parities (OR= 3.28) compared to those weighing ≥139kg. Sows with weight gain <25kg at the 1st pregnancy had higher odds of STB2 (OR= 3.01) compared to sows gaining >35kg. Each 10kg of increase in weight at the 1st weaning or in weight gain from the 1stAI to the 1stweaning decreased the total culling rate (OR= 0.71 and 0.73, respectively) and culling for reproductive reasons (OR= 0.57 and 0.61, respectively). The culling rate until the 3rdfarrowing was also increased in sows with a smaller first litter size. The results show that not only reaching a minimum weight at the 1st AI but also having an adequate body weight gain until the 1st weaning is important for the reproductive performance, productivity and retention of Landrace x Large White Danbred sows in the herd.

Behaviour and growth performance of low-birth-weight piglets cross-fostered in multiparous sows with piglets of higher birth weights

The aim of the study was to evaluate the behaviour, pre-weaning survival rate and growth performance of low birth weight (BW) piglets cross-fostered with piglets of higher weights. Piglets were transferred to 60 foster sows, and divided in three groups (G; n=20): G1- 12 low BW piglets (0.80 - 1.25kg); G2- six low BW piglets and six intermediate BW piglets (1.40 - 1.60kg), and G3- six low BW piglets and six high BW piglets (>1.70kg). For the analysis, groups G2 and G3 were subdivided in LG2 (six G2 light piglets); IG2 (six G2 intermediate piglets), LG3 (six G3 light piglets), and HG3 (six G3 heavy piglets). Behavioural observations were carried out on days 1, 2, 4 and 6 (visual direct observation) and on days 3 and 5 (video recording) after birth. The percentage of missed nursings was higher in LG3 piglets than in LG1, IG2 and HG3 piglets, on days 1 and 2. On day 4, light piglets (LG1, LG2 and LG3) missed more nursings than IG2 and HG3 piglets. On day 3, video recording showed a higher percentage of missed nursings in LG1, LG2, and LG3 piglets as compared to HG3 piglets. On day 1, the number of fights during nursing was higher in IG2 than in LG1 and LG3 piglets. Also on day 1, number of fights and percentage of piglets engaged in fights, during 15min after nursing, were higher in LG1, LG3 and HG3 than in LG2 piglets. More playful behaviours were observed on day 2 in IG2 and HG3 piglets compared to LG1, LG2 and LG3 piglets. Light piglets (LG1, LG2, and LG3) presented similar body weight on days 4, 8, 12 and 16 after birth, regardless of being mixed with piglets of higher weights or not; however, the survival rate until day 16 was most compromised in LG3 piglets compared to the other groups. Despite the lack of influence of littermates' weight on the growth of low BW piglets, their survival rate indicates that they should not be mixed with high BW piglets.

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.

Efeito da ordem de parto e da perda de peso durante a lactação no desempenho reprodutivo subsequente de matrizes suínas

Investigou-se o efeito da ordem de parto (OP) e da perda de peso durante a lactação no desempenho reprodutivo de 666 matrizes suínas. Foram formadas três classes de OP (OP1, OP2 e OP3-5) e duas classes de percentual de perda de peso (≤1% e >1%) durante a lactação. Foram avaliados: taxa de parto, intervalo desmame-estro (IDE) e tamanho da leitegada subsequente. Houve interação de OP versus perda de peso na taxa de parto das fêmeas (P<0,05). As fêmeas OP1 e OP2 tiveram maior chance (P<0,05) de não parir na classe >1% de perda de peso. A maior perda de peso não foi um fator de risco para não parir na condição OP3-5 (P>0,05). Não houve interação de OP versus perda de peso (P>0,05) para IDE e total de leitões nascidos. Fêmeas OP1 apresentaram IDE mais longo e menor tamanho da leitegada no parto subsequente (P<0,05) do que fêmeas OP2 e OP3-5. As perdas corporais na lactação não influenciaram o IDE (P>0,05), mas reduziram o tamanho da leitegada subsequente (P<0,05). Conclui-se que maior perda de peso na lactação resulta em aumento de falhas reprodutivas nas fêmeas mais jovens e reduz o tamanho da leitegada subsequente em todas as OP.

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.

Newborn piglet traits associated with survival and growth performance until weaning

Pre-weaning piglet mortality represents significant economic losses, and approximately half of this mortality occurs within the first 3 days after birth. Factors involved in postnatal mortality can also be associated with a poor growth performance until weaning. The aim of this study was to evaluate the effect of some variables measured right after birth on piglet survival during the first week of life and growth performance until weaning. Piglets included in the analysis (n=612) were born from 3 to 5 parity sows. Piglets were monitored for blood oxygen saturation (SatO2), heart rate (HR), blood glucose concentration, rectal temperature at birth (RT0 h) and at 24h after birth (RT24 h). Genetic line, birth following or not an obstetric intervention, birth order, sex, skin color, integrity of the umbilical cord, and time elapsed from birth until first attempts to stand were also recorded. Piglets were weighed at birth (BW), and at 7, 14 and 21 days after birth in order to evaluate their postnatal development. Cumulative mortality rates were 3.3%, 5.4% and 8.7% at 3, 7 and 21 days after birth, respectively. Body temperature at birth (RT0 h) did not affect (P>0.05) the survival nor the piglet growth performance. Piglets with cyanotic skin and those that took more than 5 min to stand showed higher chance of mortality (P<0.05) compared to normal skin piglets and to piglets which stood before 1 min, respectively. Piglets with broken umbilical cord had higher odds (P<0.05) of mortality up to 3 days after birth, respectively. Higher odds (P<0.05) of mortality up to 3 or 7 days were associated with later birth order (>9), low BW (<1275g), low (24-30 mg/dl) and high (45-162 mg/dl) blood glucose concentrations, or low RT24 h (<38.1°C). Piglets with BW<1545 g, low RT24 h (<38.6°C) and female piglets had higher odds of a low weight at weaning (P<0.05). Among the factors studied, cyanotic skin, delay for standing, broken umbilical cord, high birth order, low BW, low RT24 h, and both low and high blood glucose concentrations are indicators of a lower ability of piglets to survive during the first week after birth. The growth performance until weaning is compromised in piglets with a lower BW, a lower RT24 h and if they are female pigs.

Absorção de IgG via colostro em leitões biológicos e adotados após a uniformização da leitegada

Nove fêmeas de quinto parto (OP5) foram imunizadas com 4mg e 2mg de albumina sérica bovina (BSA) aos 70 e 100 dias de gestação, respectivamente. A uniformização da leitegada foi realizada 4,9±1,9h após o nascimento, antes de os leitões efetuarem a primeira mamada. As leitegadas foram compostas por cinco leitões biológicos (LB) e cinco leitões adotados (LA), com pesos semelhantes ao nascimento. Foram coletadas amostras de sangue dos leitões ao nascimento e 24h após, das fêmeas ao pós-parto e de colostro de cada grupo de tetos ao parto e 24h após. As amostras de soro e colostro foram quantificadas para IgG pelo ELISA indireto. A densidade ótica de IgG anti-BSA (DOIgG-BSA) dos leitões (24h de vida) foi correlacionada com a das fêmeas. A DOIgG-BSA entre LB e LA foi semelhante, assim como entre os grupos de tetos, ao parto e 24h após. Entretanto, ocorreu redução na DOIgG-BSA do parto até 24h após. LB e LA absorveram a mesma quantidade de IgG via colostro, quando a uniformização foi realizada até 5h pós-parto, independentemente do teto em que os leitões mamaram, uma vez que esses possuem a mesma concentração de IgG.

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.

Reproductive performance of gilts according to growth rate and backfat thickness at mating

The study evaluated the influence of growth rate (GR) and backfat thickness (BF), at first mating of gilts, on the reproductive performance until the first farrowing and on the variation in birth weight of piglets. Gilts were categorized into three groups according to GR from birth until the first mating: GRI (600-700 g/d; n = 345), GRII (701-770 g/d; n = 710) and GRIII (771-870 g/d; n = 366). Analyses were also performed considering three groups formed according to BF (mm) at mating: BFI (10-15 mm; n = 405); BFII (16-17 mm; n = 649)and BFIII (18-23 mm; n = 367). There were no differences in farrowing rate and return to estrus rate among BF or GR groups (P > 0.05). GRII and GRIII females had larger litter size compared to GRI gilts (P < 0.05), respectively, 0.5 and 0.9 more piglets, but a greater percentage of intra-partum stillborns (P < 0.05) was observed in GRIII than in GRI and GRII females. Moreover GRIII females had more piglets (P < 0.05) weighing less than 1,200 g, litters with a greater coefficient of variation for birth weight and a greater percentage of litters with a coefficient of variation above 20% (P < 0.05) than GRI females. More total born and born alive piglets were observed in BFII compared with BFI females (P < 0.05). There were no differences among BF groups in number of stillborn neither in variables concerning the birth weight of piglets (P > 0.05). These results show that there is no advantage, in terms of farrowing rate and number of born alive, in performing the first mating of gilts with GR> 770 g/d and BF > 17 mm.

Growth, body state and breeding performance in gilts and primiparous sows

Optimizing gilt management is a critical point to improve breeding herd efficiency. This review describes the effects of growth rate (GR) and body state at onset of puberty stimulation or at first mating on gilt puberty attainment, productivity and sow longevity. Traditional management practices should be re-evaluated with attention to different modern genotypes. It is difficult to discern the real effects of age, weight, backfat depth and estrus number at first insemination on longevity and reproductive performance, because these variables affect one another. GR interacts with age at boar exposure to influence age at puberty. Higher lifetime GR gilts (>700 g/d) attain puberty earlier and have a lower anoestrus rate. If gilts attain a target weight (135-150 kg), are adapted to herd health status and have at least one previously recorded estrus, they can be inseminated. Overweight at first breeding and throughout gestation should be avoided. There is no advantage in breeding gilts heavier than 150 kg; at first farrowing the target weight is 180-185 kg. Piglet production at first parity may be increased in gilts with a high GR but the number of stillborn piglets can also be increased. The culling rate over 3 parities for locomotion problems, which is one of the major risk factors for reduced herd retention rate, can be increased in overweight gilts at first breeding (>150-170 kg).

Perfil de natimortalidade de acordo com ordem de nascimento, peso e sexo de leitões

Foram acompanhados 575 partos para avaliar a influência da ordem de nascimento, do sexo e do peso dos leitões na ocorrência de natimortos. Dos 7061 leitões, 90,2%, 6,0% e 3,8% nasceram vivos, natimortos ou mumificados, respectivamente. O percentual de partos com natimortos foi 44,5%. Partos com dois ou mais natimortos foram responsáveis por 63,1% das perdas por natimortalidade, embora tenham sido responsáveis por 17,2% das leitegadas. O percentual de natimortos aumentou com a ordem de nascimento; a maior taxa de natimortos, 21,7%, ocorreu a partir da 14ª ordem. A taxa de natimortalidade foi de 3,6% e 10,1% nos leitões de primeira a nona e de 10ª a 13ª ordem, respectivamente. Em leitões com até 500g a taxa de natimortos foi de 52,1%, mais alta que a de leitões mais pesados. Em leitões com 501 a 1200g foi de 10,1%, maior que entre os com mais de 1200g (4,0%). Não houve efeito de sexo dos leitões na ocorrência de natimortos, que foi de 6,2% e 5,8% para machos e fêmeas, respectivamente. A natimortalidade é maior entre os leitões com baixo peso ou com ordem de nascimento elevada.

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.

Artificial Insemination of Gilts with 1.5 Billion Sperms Stored in Different Periods Associated with Different Pre-ovulatory Intervals

This study evaluated the reproductive performance of gilts inseminated at three intervals before ovulation (0-12, 13-23, 24-30 h) with sperm doses (SD) stored for 0-48 and 96-120 h. A total of 218 PIC Camborough 22 gilts were inseminated once with SD of 1.5 x 10(9) sperms. Pregnant gilts (n = 166) were slaughtered 30.8 +/- 3.7 days after artificial insemination. The number of corpora lutea (CL) and total embryos (TE) was counted. Pregnancy rates (PR) were analysed by chi-square test. TE and embryonic survival (ES), obtained as the ratio between viable embryos and CL, were analysed by GLM procedure (SAS) and mean values were compared by Tukey's test. Pregnancy rate was similar among artificial insemination-ovulation (AIOV) intervals when semen was stored for 0-48 h. However, the lowest PR was observed in the 24-30 h AIOV interval with storage time (ST) of 96-120 h (p < 0.05). There was a significant effect of the interaction between ST and AIOV (p < 0.05) on TE and ES variables. Total embryos and ES did not differ (p > 0.05) among AIOV intervals in ST of 0-48 h. However, gilts inseminated at 24-30 h AIOV interval with ST of 96-120 h showed a reduction of 6.7 embryos (p < 0.05) compared with gilts in the same interval inseminated with semen stored for 0-48 h. ES for the 24-30 h AIOV interval and ST of 96-120 h was lower than that observed in the other groups (p < 0.05).

Influence of Sperm Cell Dose and Post-insemination Backflow on Reproductive Performance of Intrauterine Inseminated Sows

This study was carried out to evaluate the effects of the sperm cell dose and semen backflow on the pregnancy rate and number of embryos of sows inseminated once at 0-24 h before ovulation, using an intrauterine technique. The results were analysed from a total of 211 sows assigned to three groups inseminated with doses of 0.25 x 10(9) (T1), 0.5 x 10(9) (T2) and 1.0 x 10(9) (T3) spermatozoa. Semen backflow was observed in 95% of the females (143/151) evaluated for this purpose. The percentage of semen backflow is close to two-third of the volume and the percentage of sperm is around 15% of the infused sperm dose. Intrauterine insemination can be successfully performed provided that at least 0.5 billion of sperm cell dose is infused at an interval of 0-24 h before ovulation.

Erros de anotações na elaboração de índices de produção em granjas industriais de suínos no Sul do Brasil

Foram realizadas observações em quatro granjas de suinocultura industrial nas 24 horas do dia, registrando-se o número de fetos mumificados, de natimortos, de nascidos vivos e total segundo as observações feitas por funcionários da granja (FUN) e por pesquisadores (AO). Foram também registrados resultados de um número semelhante de anotações das mesmas características no período imediatamente anterior à pesquisa, obtidas dos relatórios das granjas. Verificaram-se diferenças entre as avaliações dos FUN e dos AO quanto aos registros dos mumificados e total de nascidos em todas as granjas (P<0,05). A diferença no número de natimortos ocorreu em três granjas (P<0,05) e de nascidos vivos em apenas uma (P<0,05). Os percentuais máximos de mumificados, de natimortos, de nascidos vivos e total não registrados pelos FUN foram 67,8%, 34,5%, 1,8% e 5,1%, respectivamente. Os percentuais máximos das mesmas características não registrados pelos FUN no período imediatamente anterior à pesquisa foram 70,4%, 82,1%, 10,5% e 16,5%.

Comportamento de leitoas gestantes submetidas a dietas com baixo ou alto nível de fibra e mantidas em gaiolas ou em baias

Avaliou-se o comportamento de leitoas gestantes que receberam dietas com baixo (BF= 4,5%) ou alto (AF= 13%) conteúdo de fibra bruta, alojadas em gaiolas individuais ou baias coletivas. Foram consideradas a postura e esteriotipias adotadas pelas fêmeas em três momentos: 10 e 30 minutos após o final do consumo da manhã (10AP e 30AP) e 10 minutos antes do arraçoamento da tarde (10AN). Para as fêmeas em baias, não houve associação das dietas com postura ou esteriotipias (P>0,05). Naquelas em gaiolas, a dieta AF esteve associada à menor freqüência da posição de pé e maior freqüência da posição deitada (P<0,05), aos 10AP. Aos 30AP, a dieta BF e o alojamento em gaiolas estavam associados com o aumento da postura sentada e diminuição na deitada (P<0,05). Aos 10AN, houve aumento na postura de pé e diminuição na deitada das fêmeas em gaiolas, independentemente da dieta (P>0,05). Nas fêmeas em gaiolas, a dieta AF esteve associada à redução de esteriotipias aos 10AP e 30AP. O alojamento em baias coletivas esteve associado à maior ausência de esteriotipias (P<0,05) aos 30AP. Aos 10AN, a dieta ou o local de alojamento não estavam associados com a ocorrência de esteriotipias (P>0,05). A dieta AF, quando administrada às fêmeas em gaiolas, reduziu a postura de pé aos 10AP e aumentou a ausência de esteriotipias aos 10AP e 30AP, o que sugere aumento do bem-estar das leitoas. A ansiedade das fêmeas em gaiolas, expressa pela maior ocorrência da postura de pé, aos 30AN, não foi reduzida com a dieta AF.

The effect of post-ovulatory artificial insemination on sow reproductive performance

In order to increase reproductive performance, sows are usually inseminated several times during oestrus. In practice, this results in a significant number of sows receiving one or more post-ovulatory inseminations. This study was carried out to determine the percentage of sows that receive one or more post-ovulatory inseminations and the effect of such treatment on reproductive performance. The results were analysed from a total of 1298 sows on two farms. It was observed that more than 70% of the sows received at least one post-ovulatory insemination and approximately 20% received two or more. There was no observed effect on the rate of return to oestrus, farrowing rate or litter size (p > 0.05).

Gonadal sperm reserve in purebred Landrace and Large White boars of high average daily gain

The present study investigated the effects of average growth rate (AGR) levels and age on the number of sperm cells per gram of testis parenchyma and on the gonadal reserve in Landrace (LD) and Large White (LW) boars. In Experiment 1, the effects of breed (LD, LW), level of AGR from birth up to 90 days of age (Level 1: 384 +/- 32 g/day; Level 2: 512 +/- 22 g/day; Level 3: 624 +/- 41 g/day), and age (13, 15, 17, 19 and 21 weeks) on testicular cell concentration were evaluated. Data were analyzed under a 2 x 3 x 4 factorial design. There were significant effects associated with breed (P < 0.001) and age (P < 0.001) but not with AGR (P > 0.05) on sperm cell number per gram of testicular parenchyma. The number of cells increased with age and was greater in LW than in LD young boars, mainly those up to 19 weeks of age. In Experiment 2, the effect of two AGR levels (Level 1: 649-694 g/day; Level 2: 813-885 g/day) from birth up to 100 kg body weight on the number of sperm cells per gram of testis parenchyma and on the gonadal reserve was investigated using 59 purebred LD and LW boars. The boars were castrated at 23, 25, 29 and 33 weeks of age. Age of boars significantly affected gonadal sperm reserve and the number of sperm cells per gram of testicular tissue (P < 0.001). Breed of boars and AGR Levels did not significantly affect number of sperm cells and gonadal sperm reserve (P > 0.05). It was concluded that the number of sperm cells in the testicular tissue of young boars is influenced by their breed and age, but not by the level of their AGR.

Influência da infusão transcervical de plasma seminal ou de estrógeno na concepção, no ciclo estral e na ovulação de porcas

O objetivo deste trabalho foi o de avaliar o desempenho reprodutivo de 211 porcas da linhagem Camborough 22<FONT FACE=Symbol>â</FONT> , de diferentes ordens de parto, submetidas à infusão transcervical de plasma seminal ou de estrógeno no início do estro. Após o desmame, elas foram examinadas duas vezes ao dia para a detecção do estro, na presença de um macho sexualmente maduro, e da ovulação, com auxílio da ultra-sonografia transcutânea. No início do estro as fêmeas receberam aleatoriamente uma infusão transcervical de plasma seminal, de estrógeno ou permaneceram como grupo-controle. Todas as fêmeas foram inseminadas no turno seguinte à detecção do estro, recebendo no máximo três inseminações com intervalos de 8 a 16h. No grupo-controle as fêmeas de primeiro parto ovularam mais precocemente que as fêmeas com maior número de partos (P<0,05). Os tratamentos não influenciaram a duração do estro e o momento da ovulação. O número total de leitões nascidos não diferiu entre os tratamentos.

Fatores de risco associados ao desempenho reprodutivo da fêmea suína

Durante um ano foi realizado um estudo epidemiológico em 10 sistemas de produção de suínos (produtores de leitões ou ciclo completo), com o objetivo de investigar os fatores de risco que melhor explicam as variações na produtividade da fêmea suína. Foi aplicado um questionário para obtenção de informações relacionadas a genética, sanidade, nutrição, instalações e manejo. As respostas envolveram 271 fêmeas. Elas foram submetidas a procedimentos estatísticos de análise descritiva, análise de correspondência múltipla e classificação hierárquica ascendente das fêmeas. Dessas, 236 (87,1%) pariram em média 11,4± 2,8 leitões, 31 (11,4%) apresentaram retorno ao estro, 3 (1,1%) abortaram e 1 (0,4%) apresentou falsa gestação. As variáveis explicativas que melhor discriminaram as fêmeas quanto ao número total de leitões nascidos (variável objetiva) foram: antecedentes reprodutivos, infecção urinária, temperatura retal no dia da cobrição e até quatro dias após, tempo de cobrição, método de cobrição e soroconversão para parvovírus. Os resultados sugerem que é possível melhorar o desempenho reprodutivo dos rebanhos suínos pela identificação e correção dos fatores de risco identificados neste estudo.

Effect of the time of artificial insemination with frozen-thawed or fresh semen on embryo viability and early pregnancy rate in gilts

The aim of the present study was to evaluate the effect of artificial insemination time (before or after ovulation) using either fresh or frozen-thawed boar semen on embryo viability and early pregnancy rate. Seventy-seven prepubertal crossbred (Landrace x Large White x Duroc) gilts were inseminated in 4 treatments. Artificial inseminations were performed 6 h either after (A) or before (B) ovulation using frozenthawed (A-frozen, n = 19; B-frozen, n = 19) or fresh semen (A-fresh, n = 21; B-fresh, n = 18). The gilts were induced to puberty by administration of 400 IU of eCG and 200 IU hCG (sc) followed by 500 IU of hCG (sc) 72 h later. Ovulation was predicted to occur 42 h after the second injection. All animals were slaughtered 96 h after AI. Embryos were collected and classified as viable (5- to 8-cells, morulae, compacted morulae and early blastocysts) and nonviable (fragmented, degenerated and 1- to 4-cell embryos). The total embryo viability rate was: 64.3% (A-frozen), 54.2% (A-fresh), 76.0% (B-frozen), 91.9% (B-fresh); (A-fresh vs B-fresh, P = 0.018; A-frozen vs B-frozen, P = 0.094). It was observed that AI before ovulation resulted in a higher percentage of total viable embryos than AI after ovulation (P = 0.041). The early pregnancy rate, defined as presence of at least one viable embryo, was 78.9, 80.9, 84.2 and 94.4% for A-frozen, A-fresh, B-frozen, B-fresh, respectively. There was no significant difference in the early pregnancy rate among groups. In conclusion, there was a detrimental effect upon total embryo viability rate when AI was performed after ovulation with either frozen-thawed or fresh semen. The total embryo viability rate and the early pregancy rate were not affected by AI with either frozen-thawed or fresh semen regardless of the time of AI.

Isolation and identification of chicken infectious anemia virus in Brazil

Seven chicken infectious anemia virus (CIAV) isolates were obtained from seven broiler flocks with poor performance in two states of Brazil. All isolates induced thymus atrophy, bone-marrow aplasia, and low hematocrit values when inoculated into 1-day-old susceptible chicks. The CIAV isolates were resistant to treatment with chloroform and were able to pass through 50-nm-pore-size filters. CIAV-specific antigens could be demonstrated in tissues of experimentally infected chicks using a monoclonal antibody specific for CIAV. These characteristics of the virus and the virus-induced lesions demonstrate that CIAV is present in Brazil and that the virus is associated with production problems.

Survival of pig embryos flushed from the reproductive tract immediately or two hours after slaughter of donors

Four- to eight-cell embryos were collected from genital tracts of slaughtered gilts. Prepuberal donors were synchronized and superovulated by PMSG and hCG, inseminated and eventually slaughtered approximately 78 h after the expected time of ovulation. Genital tracts were flushed either immediately after slaughter (group A) or after 2 h storage at either 37 degrees C (group B) or 20 degrees C). Best results were achieved in group A, followed by group B and, by a wide margin, group C. Differences in viability of embryos became more evident with longer culture times.