Assessment of diagnostic accuracy and effectiveness of trans-abdominal real-time ultrasound imaging for pregnancy diagnosis in breeding sows under intensive management.

Early and accurate determination of pregnancy is critical to optimum reproductive performance in pigs and enables farmers to early rebreed or cull non-pregnant animals. Most of the conventional diagnostic methods are unsuitable for systematic application under practical conditions. The advent of real-time ultrasonography has made it possible to establish relatively more reliable pregnancy diagnosis. The present study was carried out to evaluate the diagnostic accuracy and effectiveness of trans-abdominal real-time ultrasound (RTU) imaging vis-à-vis pregnancy status in sows reared under intensive management. Trans-abdominal ultrasonographic examinations were performed using a mechanical sector array transducer and portable ultrasound system in crossbred sows from 20 days post-insemination for up to next 40 days. Animals were followed up for subsequent reproductive performance with farrowing data used as the definitive test for deriving predictive values. Accuracy for diagnosis was determined by diagnostic accuracy measures like sensitivity, specificity, predictive values, and likelihood ratios. Before 30 days of breeding, RTU imaging had 84.21% sensitivity and 75% specificity. Relatively higher false diagnosis rates were obtained in animals checked at or before 55 days after AI than in animals checked after 55 days (21.73% versus 9.09%). Negative pregnancy rate was low with 29.16% (7/24) false positives. Overall sensitivity and specificity, using farrowing history as the gold standard, were 94.74% and 70.83% respectively. The sensitivity of testing tended to be slightly lower in sows with litter size of less than 8 total born piglets, compared to sows with 8 or more piglets. Overall positive likelihood ratio was 3.25 while negative likelihood ratio was 0.07. The results indicate that pregnancy in swine herds can be reliably detected earlier in gestation by 30 days post-insemination using trans-abdominal RTU imaging. This non-invasive technique with portable imaging system can be used as an integral part of reproductive monitoring and sound management practices for profitable swine production systems.

Genetic evaluation of growth and reproductive performances of crossbred pigs reared under intensive system in tropical humid coastal climate.

Pig farming is one of the most economically viable options for the rural backward and resource-poor farmers in Asian countries. Growth rate and litter size are the most important traits based on which the crossbreeding programs are typically planned in commercial pig farming. The modern system of farming with high yielding improved pig germplasm helps in economic growth in piggery enterprises. The present study was undertaken to evaluate the influence of various genetic and non-genetic factors on growth and reproductive performances of 75% crossbred progenies of Large White Yorkshire and indigenous Agonda Goan pigs. Body weights were recorded at birth, weaning, and at monthly intervals up to 10 months of age. Reproductive performances were also recorded for litter size and weights at birth and weaning stages, age at first farrowing, number of services per conception, farrowing interval, and pre-weaning mortality. The general linear model was used to estimate overall least square means of body weights at different ages considering the effects of different factors at certain levels viz., generation (i = first, second, third, fourth), sex (j = male, female), litter size at birth (k = 1-3, 4-6, 7-9, ≥10), parity (l = 1, 2, ≥3), season (m = summer, rainy, spring), and period of birth (n = 2012-2015, 2016-2019). The heritability and genetic correlations for different traits were estimated by restricted maximum likelihood (REML) method using WOMBAT software. The re(production) parameters were analyzed to assess the genetic improvement in successive generations. There was significant difference (p < 0.01) in body weights among different generations where animals belonging to latest generation showed maximum body weights indicating ideal selective breeding in the herd. Other fixed effects also had significant effects on growth performance which clearly signifies to the crucial influence of rearing environment and animal factors like parity of dams as well as litter size at birth. The overall birth weight, weaning weight, and weight at 10 months of age were 1.00 ± 0.01 kg, 7.57 ± 0.07 kg, and 81.58 ± 1.96 kg, respectively. Nevertheless, weaning weight and weight at marketing age (8 months) were 8.04 ± 0.27 kg and 75.48 ± 1.40 kg, respectively, in fourth generation, indicating higher post-weaning growth rate of 337.20 g/day. During this fourth generation, mean litter size at birth was 8.35 ± 0.43 and litter size at weaning was 7.79 ± 0.39 with lowest percentage of pre-weaning mortality (4.11 ± 1.51). The average age at first farrowing and farrowing interval was 293 ± 17.24 and 195 ± 4.78 days, respectively. There was apparently greater genetic gain in each generation except for the second generation which might be due to the environment and managemental issues that hindered reproductive performance traits and body growth. The heritability estimate for weaning weight was 0.45 and higher heritability values were observed for all the body weights except weight at third month. Genetic as well as phenotypic correlations were moderate to high among the growth traits. The heritability and genetic correlations at birth and weaning indicate the reliability of selection at an early age. The findings indicated that there is scope for improvement through genetic selection in later generations and the 75% crossbred pigs thrived well in the prevailing hot and humid tropical coastal climate. The improved germplasm could satisfy the farmers' need in a commercial venture with high economic return.