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).     

The intensity of resistance by mature Merino ewes against Haemonchus contortus and Tichostrongylus colubriformis in single-species and combined-species infection

Three-year-old, non-lactating and non-pregnant Merino ewes, raised on pasture under a program of strategic treatment with anthelmintic and found to be extremely resistant to "trickle" infection with Haemonchus contortus, were given single-dose infections with either H. contortus or Trichostrongylus colubriformis or both species together. The purpose was to ascertain the intensity of protective immunity against the 2 parasites in sheep with immunity acquired from a presumably slight exposure to infection. To provide a criterion, some infected ewes were immunosuppressed with corticosteroid, dexamethasone. Untreated ewes were extremely resistant to challenge infection with either 15,000 or 150,000 H. contortus or 15,000 T. colubriformis. Surprisingly, when mixed infection was given, egg counts for H. contortus were significantly elevated compared with infection by that species alone. Antibody to antigens from infective larval and adult H. contortus was measured in serum by enzyme-linked-immunosorbent assay (ELISA) during the course of infection. Serum titres against larval antigens were significantly depressed when infections with either H. contortus or T. colubriformis were permitted by immunosuppression with dexamethasone, whereas those against adult antigen were depressed when infection with T. colubriformis was permitted.     

Disease-husbandry associations in farmed crocodiles in Queensland and the Northern Territory

SUMMARY To investigate husbandry-disease associations in farmed crocodiles 7 farms in Queensland and the Northern Territory were visited and details of past and present farm design and husbandry practices were recorded. In addition pathological examination of 300 (mostly young) crocodiles was carried out (85 necropsied, one biopsied and 214 examined retrospectively). Mortality rate and occurrence of disease, especially opportunistic infections with bacteria and fungi, were highest during winter months and in farms located at greater latitudes. A difference in the presence and prevalence of disease between the initial establishment phase of Northern Territory crocodile farms (1984–87) and currently (1988–91) was apparent; parasitic infections are now relatively infrequent and bacterial septicaemias and mycoses less common as a result of some provision of artificial heating for juveniles. Gross and microscopic changes observed in visceral and periarticular gout, bacterial hepatitis/septicaemia, deep and superficial mycosis, pentastomiasis and other parasitic infections are described.     

The effect of modified roofing on the milk yield and reproductive performance of heat‐stressed dairy cows under hot‐humid conditions

The objective was to measure the effects of cooling techniques (shade cloth vs. normal roof) on performance and physiology of 16 Friesian crossbred cows (87.5% Holstein Friesian × 12.5% Brahman) located at Sakol Nakhon Livestock Research and Testing Station, Department of Livestock Development, Ministry of Agriculture and Cooperatives (Sakol Nakhon, Thailand). They were divided randomly into two groups of eight. The two groups were used to evaluate the effects of modified roofing (normal roof fitted with woven polypropylene shade cloth) on the subjects' milk yield and reproductive performance under hot humid conditions. Results indicated that the modified roofing offered a more efficient way to minimize heat stress than the normal roof. The difference was sufficient to enable the cows to have a significantly lower mean rectal temperature and respiration rate (38.56°C, 61.97 breaths/min) than that of the cows housed under normal roofing (39.86°C; 85.16 breaths/min). The cows housed under modified roofing produced more milk (P < 0.05) but did not differ significantly in reproductive performance from the cows housed under normal roofing.     

Colour‐Doppler ultrasound imaging as a laparoscopy substitute to count corpora lutea in superovulated sheep

This study evaluated colour‐Doppler ultrasound imaging (UI) as a substitute for laparoscopy to count the corpora lutea (CL) in superovulated sheep. Twenty‐five Santa Ines ewes were superovulated three times at 21‐day intervals. Corpora lutea were counted by colour‐Doppler UI (CL_DOPPLER) 6 days after each superovulation and confirmed by laparoscopy (CL_LAP) 12 hr later. The mean number of CL was similar for both techniques (2.1 ± 2.5 vs. 2.1 ± 2.7 for CL_DOPPLER and CL_LAP, respectively) with a significant positive correlation (r = .94; r²=.89). Colour‐Doppler UI effectively evaluated the ovarian response in superovulated ewes and efficiently identified animals that did not respond to superovulation.