Ana Paula Gonçalves Mellagi

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.

Factors associated with return to estrus in first service swine females

Reproductive failure is a major factor contributing to the culling rate of swine females. As return to estrus is the most frequent reproductive failure, the study of factors associated with its occurrence can help to identify females with a predisposition to this failure. This study was run in a farm with a housing capacity of 1500 Agroceres PIC females in southern Brazil. Logistic regression models were run to determine the relative contribution of some factors to the probability of a sow returning to estrus. Return to estrus occurred in 27.8% (10/36) and 10.7% (50/469) of females remated after a previous reproductive failure and first service females, respectively. Females with a previous reproductive failure had 3.2-times higher odds (P=0.003) of returning to estrus than first service females. In first service females (n=469), higher odds (P<0.05) of returning to estrus were observed in parity order (PO) 0 (14.3%; 3.1-times), PO1 (20.6%; 4.9-times) and PO2 (12.7%; 2.7-times) compared to PO>2 (5.0%; reference class) females. Weaned females with ovarian cysts, detected during estrus, had 7.6-times higher (37.5%; 3/8) odds (P=0.012) of returning to estrus than females without cysts (8.3%; 28/338). In the model run with 330 weaned sows, the return to estrus rate was not affected (P>0.05) by the number of weaned piglets (7-9; 10; 11 and 12 piglets) but sows with a lactation length (LL) of 15-19 days had 3.5-times higher odds (P<0.05) of a return to estrus than sows with LL of 20-21 days. Return to estrus in weaned sows was also affected by the interaction between PO and body condition score (BCS) loss during lactation. Loss of more than 0.5 point in BCS resulted in higher odds (P<0.05) of returning to estrus in PO1 and PO2 but not in PO>2 sows. Accurate detection of estrus in gilts and adequate feed intake during lactation of first and second parity sows are suggested to reduce return to estrus rate in younger females. To avoid the detrimental effect of short lactations on reproductive performance options such as increasing the lactation length, split-weaning or skip-mating may be considered.

Caracterização e desempenho reprodutivo de fêmeas suínas submetidas à intervenção obstétrica manual

The aim of this study was to determine the characteristics of farrowings with manual intervention and to evaluate the effect of this intervention on the subsequent reproductive performance and culling rate. Data of 4121 farrowings were separated in Control (3271 farrowings) and Intervention (850 farrowings) groups. The percentage of farrowings submitted to manual intervention was 20.6%. There was no difference (P>0.05) in the occurrence of intervention according to litter size classes ( 14 piglets). The proportion of intervention at parturition increased (P<0.05) during summer and in higher parity order (PO) females. In farrowings with intervention there were longer farrowing duration in PO 1 females (P<0.05) and greater number of stillborn piglets and higher frequency of farrowings with at least one stillborn (P<0.05) in PO 1, PO 3-5 and PO 6-10 females. In the Intervention group, greater weaning to estrus interval (WEI), lower farrowing rate and lower subsequent total born piglets (P<0.05) were observed in PO 1 and 2, PO 3-5 and PO 6-10, respectively. Removal rate before first insemination post weaning, by both reproductive and non reproductive reasons, was greater (P<0.05) in Intervention group. Manual intervention at parturition is more frequent during summer and among older females. Manual obstetric intervention compromise the WEI, the farrowing rate or the subsequent litter size.

Sperm quality and oxidative status as affected by homogenization of liquid-stored boar semen diluted in short- and long-term extenders

Homogenization of diluted boar semen during storage has for a long time been regarded as beneficial. Recent studies indicated an adverse effect of homogenization on sperm quality for yet unknown reasons. This study aimed to verify the effect of homogenization on sperm parameters and to elucidate the impact of oxidative stress. Twenty-one normospermic ejaculates (21 boars) were diluted with Androstar® Plus (AND) and Beltsville Thawing Solution (BTS). Semen doses were submitted to no-homogenization (NoHom) or twice-a-day manual homogenization (2xHom) during storage at 17°C for 168h. NoHom and 2xHom were similar (P>0.05) for both short- and long-term extenders with respect to motility and kinematics parameters (CASA system), membrane viability (SYBR-14/PI), acrosome integrity, lipid peroxidation, protein oxidation, intracellular reactive oxygen species, sulfhydryl content, and total radical-trapping antioxidant potential. 2xHom reduced sperm motility and motion kinematics (VCL, VSL, VAP, BCF, and ALH) following the thermoresistance test and presented with a slight increase in pH along the storage (P=0.05) as compared to NoHom. Furthermore, 2xHom semen doses presented with a constant SOD and GSH-Px activity during storage whereas enzymatic activity increased for NoHom at the end of the storage. These findings confirm that homogenization of semen doses is detrimental to sperm quality. Moreover, it is shown that the effect of homogenization is unlikely to be primarily related to oxidative stress. Homogenization is not recommended for storage of liquid boar semen for up to 168h in both short- and long-term extenders.

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

The effect of parity (PO) and weight loss during lactation on the subsequent reproductive performance of 666 sows was investigated. Sows were allocated into three PO classes (PO1, PO2 and PO3-5) and into two classes of weight loss percentage (≤1% and >1%) during lactation. Farrowing rate, weaning to estrus interval (WEI) and total born at next farrow were evaluated. There was an interaction effect between PO and weight loss on the farrowing rate (P 0.05). There was no interaction between PO and weight loss (P>0.05) on WEI and subsequent total born. PO1 females showed longer WEI and lower litter size on subsequent farrowing compared to PO2 and PO3-5 females. Weight loss did not affect WEI (P>0.05), but it decreased subsequent litter size (P<0.05). High weight loss during lactation results an increase in reproductive failures in young females and decreases subsequent litter size in all parity orders.

The influence of air contact on the quality of extended boar semen

Background: The extensive use of artificial insemination in the swine industry emphasizes the need for distribution of good quality semen doses by the artificial insemination centers. A factor that could modify seminal quality is the contact of extended semen with environmental air. However, only few studies have investigated the effects of air presence on semen parameters. Thus, the aim of the present study was to evaluate the influence of different amounts of air on porcine semen quality during the storage period. Materials, Methods & Results: Four ejaculates from five sexually mature boars were used. Each ejaculate (n = 20) was isothermically diluted (30 x 106/mL) in a BTS-extender and assigned to three groups differing on the amount of air entrapped within the polystyrene tubes (100 mL). In group AIR-0 the tubes were completely filled with extended semen (0% air); in group AIR-25, 75% of the tube volume was filled with extended semen and 25% with air; in group AIR-50, 50% of the tube volume was filled with extended semen. The semen doses were stored at 17.3 ± 0.5oC for 120 h. The motility parameters were assessed at 24, 72 and 120 h of storage using a CASA system. The evaluation of acrosomal integrity was performed by examining formalin-fixed samples under phase-contrast microscopy (1000 x) at 72 and 120 h of storage. The pH was measured at 24, 48, 72, and 120 h of storage with a digital pH-meter. At 120 h, samples were incubated in waterbath at 38°C for the thermoresistance test and sperm motility was assessed after 30 and 120 min of incubation. For each time analysis, a different sealed tube was used in order to maintain a constant amount of air within the tubes during storage. Data were analyzed as repeated measures using the GLIMMIX procedure of SAS® Software. Boar and week of collection were included as random effect in the model. Groups were compared using the Tukey-Kramer test at a significance level of 5%. The pH was significantly influenced by the amount of air entrapped within the tubes (P 0.05). Discussion: The presence of air within tubes affects the quality of extended semen during storage, resulting in increase of pH and subsequent decrease in motility preservation. This pH-rise could be explained by the loss of CO2 from the diluted semen to the air compartment within the tube. At the same time, it is possible to infer that this event influences the intracellular pH of the spermatozoa, increasing sperm metabolism and, consequently, impairing sperm motility. Therefore, we conclude that avoiding air presence within storage containers is recommended in order to ensure the quality of boar semen doses.

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

Nine sows of fifth parity (PO5) were immunized with 4mg and 2mg of bovine serum albumin (BSA) at 70 and 100d of gestation, respectively. Cross fostering was performed 4.9±1.9h after birth, before piglets had their first suckling. Litters were composed of five biological piglets (BP) and five adopted piglets (AP), with similar weight at birth. Blood samples were collected from piglets (at birth and at 24h of life) and from females (after farrowing) and colostrum from each group of teats (at farrowing time and after 24h). Samples of serum and colostrum were quantified to IgG by indirect ELISA. Optical density of IgG anti-BSA (ODIgG-BSA) from piglets (24h of life) was correlated with dams. ODIgG-BSA was similar among BP and AP, as well as among pairs of teats (at farrowing time and after 24h). However, there was a decrease in ODIgG-BSA from farrowing up to 24h after birth. BP and AP absorbed the same amount of IgG via colostrum, when cross fostering was evaluated 5h after farrowing, regardless of the teat suckled, since these have the same concentration of IgG.

Two different feeding levels during late gestation in gilts and sows under commercial conditions: impact on piglet birth weight and female reproductive performance

The increase in the litter size in past decades has caused reduction in the individual piglet birth weight. Therefore, nutritional strategies employed in the last third of gestation in order to improve the piglet birth weight have been studied. This study aimed to evaluate the effects of 2 different feeding levels (1.8 and 2.2 kg/d) in the last third of gestation on the piglet birth weight and the female reproductive performance. A total of 407 females were fed on a diet based on corn-soybean meal (3.25 Mcal ME per kg and 0.65% standardized ileal digestible lysine) from day 90 of gestation until farrowing. The females were weighed on day 90 and day 112 of gestation, and at weaning. Born alive and stillborn piglets were weighed within 12 h of birth. The lactation feed intake and the litter growth rate were measured in a randomly selected subsample of 53 sows from each treatment. The data were analyzed using the generalized linear mixed models, considering the females as the experimental unit. Parity, treatment, and their interaction were analyzed for all responses. The females fed on 2.2 kg/d of diet from day 90 to day 112 exhibited greater body weight gain compared to the females fed on 1.8 kg/d (P < 0.001). No evidence of the effects of feeding levels on the individual piglet birth weight and on the within-litter CV were observed, for both gilts and sows (P ≥ 0.90). Similarly, when the classes of the total born piglets were considered in the analysis (<15 and ≥15 for gilts; <16 and ≥16 for sows), no positive effects of increasing the feeding level were observed on the individual piglet birth weight and the within-litter CV (P ≥ 0.47). Also, no differences in the stillborn rate, mummified-fetus rate, and percentage of piglets weighing less than 1,000 g at birth were observed between the treatments (P ≥ 0.28). The females fed on 1.8 kg/d of diet exhibited greater feed intake during lactation, compared to the females fed on 2.2 kg/d (P < 0.05). Weaning weight, weaning-to-estrus interval, subsequent litter size, and culling rate were not affected by the dietary levels (P ≥ 0.23). In conclusion, increasing the feed intake from day 90 of gestation until farrowing increased the body weight gain in sow, demonstrated no effect on the piglet birth weight, and reduced the lactation feed intake. Furthermore, there was no evidence of the effects of the treatments on the litter growth rate or on the subsequent female reproductive performance.

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

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.

Proposal of Equations for Predicting Post-Farrowing Sow Weight

Background: Body condition score is used widely in swine production to ensure adequate nutritional levels in sows during gestation and lactation. However, body condition score is not a gold standard for the estimation of nutritional requirements in sows. Post-farrowing sow body weight assessment might serve as a useful approach for the better adjustment of the nutritional requirements during lactation; however, this approach is time-consuming, requires labor, and might result in detrimental effects on the sow behavior and welfare. The objective of the present study, therefore, was to formulate prediction equations for the estimation of post-farrowing sow weight. Materials, Methods & Results: Seven equations were formulated for predicting the post-farrowing sow body weight, by using the data from three databases, which comprised a total 522 sows (434 gilts and 88 multiparous). The sows were weighed on Day 112 of gestation and after farrowing within 12 h. The piglets birth weight was recorded within 24 h after farrowing. The equations were formulated considering all the parity orders. While formulating the equations, the following five variables were used: pre-farrowing body weight, piglets born, litter weight, the interval between pre-farrowing weighing and farrowing (in days), and the total feed intake between pre-farrowing and post-farrowing weighing. The seven models were compared using the sets of possible predictors through regression with the best subsets procedure (Minitab for Windows, v. 18). Equations (EQ) 1, 2, and 4 were validated with a database comprising 732 sows (parity orders: 1–5). The females were weighed on Day 107 of gestation and within 24 h after farrowing. The predicted weights estimated by EQ 2 and 4 (215.4 ± 34.3 kg and 216.7 ± 34.4 kg, respectively) did not significantly differ from the observed weight (216.8 ± 34.6 kg) [P > 0.05]. Discussion: Pre-farrowing sow body weight was identified as the main input variable required for the estimation of the post-farrowing sow body weight. Thus, even EQ 1, which contained only this variable, exhibited a high coefficient of determination (R2 = 0.8707). However, the R2 value kept increasing as more input variables were included in the equation. Equation 2, 4, and 6 included the litter weight variable, and the addition of this variable increased the numerical value of R2 from 0.8707 in EQ 1 to 0.8975 in EQ 2. The EQ 3, 5, and 7 considered the piglets born variable as well, which increased the R2 value from 0.8707 in EQ 1 to 0.9119 in EQ 3. The coefficient of determination did not vary much among the equations; therefore, the selection of the prediction equations depended on data availability, feed management, facility, and the reliability of data collection in each farm. Although EQ 1 demonstrated a greater correlation between the predicted and the observed post-farrowing weight compared to the other equations, the values of error in central tendency and the errors due to disturbances were numerically higher for EQ 1 in comparison to the other two equations (EQ 2 and 4). Therefore, it is suggested that EQ 1 should be used as the last choice for the estimation of post-farrowing sow weight as it presented low trueness and precision, and also because the predicted weight estimated by EQ 1 was statistically lower than the observed weight (211.67 ± 33.33 kg vs. 216.84 ± 34.62 kg; P = 0.012). EQ 4 emonstrated higher trueness and precision; however, it did not differ significantly from EQ 2 and 1. Further analyses are required in order to validate EQ 3, 5, 6, and 7. Among the equations that were predicted as well as validated, the simplest and the easiest equation with satisfactory results for trueness and precision was EQ 2, which is as follows: Post-farrowing sow weight (kg) = 13.03 + (0.93 × pre-farrowing body weight, kg) + (–1.23 × piglets born, n)