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AJ Landaeta-Hernández R Palomares-Naveda G Soto-Castillo A Atencio CC Chase Jr PJ Chenoweth 《Reproduction in domestic animals》2004,39(5):315-320
Social organization and breed effects following PGF2αwere studied in mature Angus, Brahman and Senepol cows allocated into two groups (each A = 5, B = 5 and S = 5). Variables including interval to oestrus onset (IEO), oestrous duration (DE), total mounts received (TMR), and oestrous intensity (IE) were derived via HeatWatch®. Breed‐type influenced IEO (B = 42.6 ± 6.7 h; S = 54.6 ± 6.0 h; and A = 27.8 ± 5.8 h; p < 0.003). Within breeds, dominant B (69.4 ± 13.3 h) and S (65.5 ± 7.4 h) cows were slower (p < 0.05) to be detected in oestrus than subordinate (38.1 ± 4.4 h) and intermediate (40.6 ± 6.0 h). However, within A, dominant cows (16.4 ± 12.5 h) were detected in oestrus earlier (p < 0.05) than intermediate (44.3 ± 9.2 h) and subordinates (32.7 ± 5.1 h). Angus (21.5 ± 2.4 h) and B (22.1 ± 3.0 h) cows had longer (p < 0.01) DE than S (9.1 ± 2.8 h). Dominants (20.4 ± 3.0) and intermediates (20.2 ± 2.3 h) cows had longer DE (p < 0.04) than subordinates (12.1 ± 2.1 h) although the interaction breed × social order showed that dominant S had shorter DE than dominant A and B (10.1 ± 3.3; 34.8 ± 6.0 h; and 20.0 ± 6.4 h, respectively; p < 0.001). Angus cows had less TMR than B (p < 0.02) and tended to be less than S cows (p < 0.06). Overall, greatest (p < 0.008) IE occurred in the first 9 h after onset of oestrus with no breed effect (p > 0.05). Dominant cows tended (p < 0.10) to have less TMR (3.2 ± 0.7 mounts) than subordinate (4.1 ± 0.4 mounts) and intermediate (4.7 ± 0.6 mounts) throughout, especially 3–6 h after oestrus onset (p < 0.07). Breed and social order both influence PGF2α‐induced oestrus behaviour. 相似文献
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During the 1997 Swedish grazing season, faeces were collected every 3 weeks on 7 occasions from young grazing cattle with moderate nematode parasite infections. From this source 12, 400 g dung pats were set up on each sampling occasion on a specially designated area of pasture. Half of these pats were placed on pasture where it was aimed to prevent snow cover during the subsequent winter. During the grazing season, herbage growth was kept at reasonably uniform height by clipping and the dung pats were protected from destruction by animals and birds. At the time of animal turn-out the following year (7th April 1998), it was observed that all dung pats had disappeared. Assessments of the survival of infective larvae, both on pasture and in soil, were made in a circular area encompassing the location of each pat. These sampling procedures were completed within a 3 week period. All faecal deposits yielded infective larvae at turn-out the following year, with proportionally greater numbers developing from nematode eggs deposited in cattle dung during the mid third of the previous grazing season. The surface layer of soil was found to be an important reservoir for infective larvae, with numbers recovered being approximately half those found in the overlying pasture samples. No significant differences were found between the normal pasture and snow excluded pasture in the number of infective larvae recovered from both pasture and soil samples. The epidemiological consequences of these findings are discussed. 相似文献
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