Growth performance and plasma insulin-like growth factor I concentrations in sheep selected for high weaning weight

A study was undertaken to determine the effect of selection for high weaning weight on concentrations of plasma insulin-like growth factor I (IGF-I) in sheep and to evaluate the usefulness of measuring IGF-I as an aid in identification of genotypes with a higher growth potential. Lambs from two lines selected for high 120-d weight (HW and DH) and an unselected control (C) were weighed and blood samples collected monthly from birth to weaning (4 mo. of age). A clear differentiation in size occurred after 1 mo of age between lines, between sexes, and between singles and twins. At weaning, selected lines were 3.8 and 5.0 kg heavier than controls. Plasma IGF-I concentrations were 1.5 to 2 times higher (P less than .001) in males than in females after 1 mo of age. There were no significant differences in IGF-I concentration between lines or types of birth. However, line DH and single lambs on average had higher concentrations of IGF-I. Within sex and type of birth correlations between IGF-I concentrations at 0, 1, 2, 3, and 4 mo and 4-mo BW ranged from -.16 to .49 in the three lines, and most were not significant. Coefficients of variation for IGF-I concentrations (36 to 50%) were two to three times higher than those for BW (11 to 15%). Due to the high variability of IGF-I measurements, the low correlations between IGF-I concentration and BW, and the small differences in IGF-I between control and selected lines, measurement of plasma IGF-I is unlikely to be an effective aid to selection for growth rate in sheep.     

Ram influence on ovarian and sexual activity in anestrous ewes: effects of isolation of ewes from rams before joining and date of ram introduction.

A 2-yr experiment was conducted to determine whether isolation of ewes from rams is necessary to achieve a high response to the ram effect and whether ewes respond as well in May as in June. The experiment was conducted at two locations, with the same four treatments at each location. The four treatments differed with respect to ewe proximity to rams before mating (isolated vs adjacent) and date of joining with novel breeding rams (May 15 vs June 15). The proximity treatment at one location was changed in the 2nd yr; teaser rams were joined with the ewes instead of being adjacent to them. Overall, 86% of the eligible ewes were judged to have responded to the ram effect. A period of isolation before mating did not increase response compared with ewes that remained adjacent to, or in contact with, rams (86 vs 85%). Response was greater (P less than .05) in June and in the 2nd yr (P = .05). A physiological response, different from that generally described, was identified. Ewes ovulated approximately 8 d (8.0 +/- .19 d) after joining with breeding rams. The subsequent ovulation, accompanied by estrus, occurred approximately 15 d later (15.3 +/- .29 d). Eighty-five percent (87/102) of the ewes sampled responded in this manner. However, 82% (31/38) of a sample of these ewes had at least one morphologically normal corpus luteum when examined by laparoscopy 4 d after joining. It seems that these corpora lutea were not completely functional with respect to progesterone production. The ram effect can be achieved without prior isolation of ewes from rams.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ovulation rate in sheep selected for weaning weight or litter size

Ovulation rate was measured by laparoscopy at two consecutive cycles on 366 ewes 2 yr old and over and 85 yearling ewes of five lines of Targhees from the base base population; 53 yearling linecross ewes were also included. The lines were two unselected controls (HCl and DC), two selected for 21 yr for increased 120-d weight (HW and DH) and one selected for 19 yr for multiple births (T). Ewes were synchronized in late July or early August at the start of the normal breeding season with intravaginal pessaries impregnated with 60 mg methylacetoxyprogesterone and examined at first and second estrus. Ovulation had occurred in both cycles in 327 (89%) and 177 (85%) of the mature and yearling ewes, respectively. Overall mean numbers of corpora lutea at first and second estrus were 1.42 and 1.63, respectively for ewes 2 yr and over and 1.20 and 1.44 for yearlings, indicating an effect of synchronizing treatment, season, flushing, or a combination of these. Among mature ewes, ovulation rate was higher (P less than .05) in DH (+.20), HW (+.19) and T (+.16) than in controls at first estrus, and in HW (+.29) and T (+.21) but not DH (-.04) at second estrus. Among yearlings, differences were significant only at second estrus (HW, +.40; T, +.35) and again not for DH (+.08). The failure of line DH to increase in ovulation rate from first to second estrus as did other lines was transmitted to linecross progeny. Body weight within line affected ovulation rate significantly, with a greater effect at second estrus, in both age groups. Adjustment for body weight removed the difference between HW and controls but not between T and controls. Repeatability of corpora lutea count was .27 and .25 for mature and yearling ewes, respectively.     

Abortions in sheep caused by Salmonella Brandenburg: Pathological findings

CASE HISTORY: A 7-year-old cat developed sporadic vomiting, reduced appetite, and weight loss over the previous 3 months.

CLINICAL FINDINGS: Palpation revealed a large mid-abdominal mass and the cat had marked eosinophilia. The cat progressively lost weight over the next 7 weeks when euthanasia was performed.

PATHOLOGICAL FINDINGS: Necropsy revealed a 3?cm diameter firm white intramural mass in the colon and another in the pylorus. Mesenteric and cranial mediastinal lymph nodes were firm, pale, and enlarged. Histopathological examination revealed foci of necrosis surrounded by thick dense collagen trabeculae and predominantly eosinophilic inflammation within the intestine and lymph nodes. Marked eosinophilic infiltration of the liver was also present.

DIAGNOSIS: The lesions were consistent with gastrointestinal eosinophilic sclerosing fibroplasia (FGESF).

CLINICAL RELEVANCE: This is the first report of FGESF in a New Zealand cat and the first time lesions of FGESF have been observed in extra-abdominal tissues. Intestinal neoplasia can be clinically identical to FGESF and histopathology is required for differentiation. Evidence suggests that FGESF has a more favourable prognosis than intestinal neoplasia.     

Serological patterns,antibody half-life and shedding in urine of Leptospira spp. in naturally exposed sheep

Abstract

AIMS: To determine within-farm prevalence, longitudinal pattern of exposure measured by serology, antibody titre longevity and point prevalence of shedding in urine of Leptospira borgpetersenii serovar Hardjo and L. interrogans serovar Pomona in naturally infected sheep on a sample of commercial farms in New Zealand.

METHODS: On eight commercial sheep farms, between September 2011 and January 2014, blood samples were collected from 115–217 ewe lambs on each farm, at intervals of 2–11 months. They were analysed by microscopic agglutination test (MAT) for antibodies to L. borgpetersenii serovar Hardjo and L. interrogans serovar Pomona, using a titre cut-point of 48. Urine from 98 animals was tested by quantitative PCR (qPCR). The half-life of antibodies was estimated in 185 sheep for serovar Hardjo and 21 for Pomona, and the seroprevalence and mean titre of animals lost to follow-up was compared with those remaining in the study.

RESULTS: Within-flock seroprevalence for serovar Hardjo reached a maximum at 17–22 months of age, ranging from 79 to 100%. Seroprevalence for serovar Pomona rose above 10% on three farms and increased to 21–54% by 4–14 months. Seroconversions occurred mainly from late autumn to early summer at 7–15 months of age. Seroprevalences ranging from 3 to 76% for serovar Hardjo and 0.5 to 15% for serovar Pomona were observed up to 3 months of age, likely due to maternally derived immunity. The half-life of antibody in response to infection was estimated to be 6.7 (95% CI=5.8–7.9) months for serovar Hardjo and 6.3 (95% CI=4.8–9.0) months for Pomona. The prevalence of sheep with urine positive for leptospires on qPCR on each farm ranged from 11 to 88%. All but one of the qPCR-positive animals were seropositive for serovar Hardjo. On two farms where Pomona exposure was observed, animals that were lost to follow-up had a higher geometric mean titre for serovar Pomona than those remaining in the study.

CONCLUSIONS: This study demonstrated seasonal exposure from autumn to early summer in young sheep, a wide range of within-flock serological and shedding prevalence, and gives an estimation of the half-life of MAT titres in sheep. More extensive data are needed to fully understand the epidemiology of leptospirosis in sheep flocks across New Zealand and, along with economic analysis, to justify and design cost-effective and efficient control measures to protect human and animal health.