Epidemiological Description of Cystic Ovarian Disease in Argentine Dairy Herds: Risk Factors and Effects on the Reproductive Performance of Lactating Cows

To describe the epidemiology of cystic ovarian disease (COD), to find possible risk factors associated with the incidence of cysts and to analyse the impact of COD on the reproductive performance of dairy cows, databases from 22 dairy herds from the main dairy region in Argentina were retrospectively evaluated throughout a 3‐year period (2009–2011). A total of 248 COD cases over 9156 parturitions were recorded, resulting in a cumulative incidence rate of 2.7%. Cystic ovarian disease incidence density was lower during the first 100 days post‐partum (DPP) than during later stages of lactation. Seasonality had a significant influence on the disease presentation with higher incidence rates during winter and spring. Cows with a previous diagnosis of clinical mastitis showed 2.72 times more chances of developing ovarian cysts. Cystic cows had longer calving to first service and calving to conception intervals and lower conception rate than controls.     

Population dynamics and economic threshold of the nematodes Radopholus similis and Pratylenchus goodeyi on banana in Australia

To help banana growers to decide when to apply nematicide, economic thresholds were determined for tropical north Queensland, subtropical south-east Queensland and northern New South Wales, Australia. This was done by monitoring nematode populations, root damage and growth parameters of bunching pseudostems in several commercial crops for several years. There was no significant consistent change in the disease index in consecutive years in any of the regions, although there was great variation between crops. However, on two crops in the tropics, the disease index of roots increased. To reduce the risk of not applying nematicide when required, the economic threshold was adjusted down to allow for this increase on some crops. In the tropics with a crop value of $25 000 ha^?1 year^?1, the economic threshold occurred at a root disease index = 9.2-15.6. In the subtropics with a crop value of $10 000-15 000, the economic threshold occurred at a root disease index = 20.5-35.5. In the subtropics, Radopholus similis (burrowing nematode) was as pathogenic as Pratylenchus goodeyi (lesion nematode) as measured by root necrosis. However, both nematodes were less pathogenic in the subtropics than was R. similis in the tropics. In the subtropics, R. similis tended to be more numerous in warmer months and P. goodeyi in cooler months.     

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.