Aims: To provide herd managers with a set of decision rules allowing them to predict the likelihood that a juvenile bull is ready for Bull Breeding Soundness Evaluation (BBSE), or breeding, if bodyweight and scrotal circumference are known.
Methods: This was a longitudinal study following two groups of young pasture-fed Holstein and Jersey bulls from northwest Tasmania, Australia. Individual scrotal circumference, bodyweight and semen characteristics were recorded at 6–8 weekly intervals, from 6–18 months of age. Classification and regression tree analyses were used to predict the probability that a bull had ≥70% normal sperm morphology based on scrotal circumference and bodyweight measurements.
Results: Overall 1,661 scrotal circumference and bodyweight measurements were obtained, and 518 semen samples from 356 bulls were assessed for sperm morphology, from 16 examination sessions that took place between 29 May 2015 and 17 August 2016. Classification and regression tree analyses generated a decision tree for Holstein bulls with four node endpoints, and for Jersey bulls with three node endpoints. Diagnostic test performance showed that for Holstein bulls, using the node endpoints of scrotal circumference ≥27?cm and bodyweight ≥349?kg, 98% had ≥70% normal sperm (positive likelihood ratio 10.4; 95% CI?=?2.7–41), and using the node endpoints of scrotal circumference ≥27?cm and bodyweight between 282–349?kg, 89% had ≥70% normal sperm (positive likelihood ratio 1.6; 95% CI?=?0.9–2.6). For Jersey bulls, using the node endpoints of bodyweight ≥259?kg and scrotal circumference ≥29?cm, 88% had ≥70% normal sperm (positive likelihood ratio 3.4; 95% CI?=?1.6–7.0).
Conclusions: This study provides a set of relatively simple decision rules based on bodyweight and scrotal circumference measurements that allows herd managers to assess the likelihood that juvenile bulls are ready for BBSE or breeding.
The effect of chlordimeform and 18 related compounds on the aggregation behavior of the negatively geotactic larvae of the cattle tick, Boophilus microplus was investigated. Aggregations were treated and hyperactivity in the forms of immediate dispersal, delayed dispersal, and prolonged leg waving evaluated. A marked structure-activity relationship with delayed dispersal resulted; most active were the N-monomethyl formamidines, N′-(2,4-dimethylphenyl)-N-methylformamidine and demethylchlordimeform. Other compounds, including chlordimeform, with structures compatible with metabolism to N-monomethyl formamidines were also active. Delayed dispersal caused by those possessing the N,N-dimethyl moiety was antagonized after inhibition of oxidative N-demethylation to N-monomethyl analogs by piperonyl butoxide. Since the N-monomethyl moiety had already been reported as important in the killing action of the formamidines in cattle tick larvae, the possibility of a relationship between delayed dispersal and acaricidal effectiveness was examined and percentage mortality at 24 hr found to correlate positively with the rate of onset of dispersal.Delayed dispersal was not characteristic of the responses to other acaricides such as lindane, allethrin, carbaryl, and coumaphos. In addition, the monoamine oxidase inhibitors, tranylcypromine, pargyline, and nialamide, did not induce delayed dispersal and showed no lethal effects. 相似文献
Anaplasma ovis (Rickettsiales: Anaplasmataceae) is a tick-borne pathogen of sheep, goats and wild ruminants. The genetic diversity of A. ovis strains has not been well characterized due to the lack of sequence information. In this study, we evaluated bighorn sheep (Ovis canadensis) and mule deer (Odocoileus hemionus) from Montana for infection with A. ovis by serology and sequence analysis of the msp4 gene. Antibodies to Anaplasma spp. were detected in 37% and 39% of bighorn sheep and mule deer analyzed, respectively. Four new msp4 genotypes were identified. The A. ovismsp4 sequences identified herein were analyzed together with sequences reported previously for the characterization of the genetic diversity of A. ovis strains in comparison with other Anaplasma spp. The results of these studies demonstrated that although A. ovismsp4 genotypes may vary among geographic regions and between sheep and deer hosts, the variation observed was less than the variation observed between A. marginale and A. phagocytophilum strains. The results reported herein further confirm that A. ovis infection occurs in natural wild ruminant populations in Western United States and that bighorn sheep and mule deer may serve as wildlife reservoirs of A. ovis. 相似文献
Two experiments were conducted to determine effects of supplemental ruminally degradable protein (RDP) vs. increasing amounts of supplemental ruminally undegradable protein (RUP) on intake, apparent digestibility, N retention, and nutrient flux across visceral tissues in lambs fed low-quality forage. Lambs were fed a basal diet of crested wheatgrass hay (4.2% CP) for ad libitum consumption, plus 1 of 4 protein supplements: isolated soy protein (RDP source) fed to meet estimated RDP requirements (CON), or corn gluten meal (RUP source) fed at 50, 100, or 150% of the supplemental N provided by CON (C50, C100, and C150, respectively). In Exp. 1, 12 lambs (29.9 +/- 2.7 kg) were used. Forage OM intake was not affected (P = 0.46) by protein degradability or by increasing RUP (P >/= 0.31). Apparent total tract OM digestibility was not affected (P = 0.10) by protein degradability, but increased (P /= 0.40) by protein degradability or level of RUP. In Exp. 2, 16 catheterized lambs (32 +/- 5 kg) were used. Net release of ammonia-N from the portal-drained viscera (PDV) was greater (P = 0.02) for CON than for C100 and increased linearly (P = 0.002) as RUP increased. Net uptake of ammonia-N by liver was not affected (P = 0.23) by protein degradability, but increased linearly (P = 0.04) as RUP increased. Net urea-N release from liver was not affected (P >/= 0.49) by protein degradability or level of RUP. Net uptake of urea-N by PDV was greater (P = 0.02) for C100 compared with CON and increased (P = 0.04) with increasing RUP. Neither net release from PDV nor hepatic uptake of alpha-amino N were affected (P >/= 0.12) by protein degradability or level of RUP. Hepatic ammonia-N uptake accounted for 82, 38, 98, and 79% of net urea-N release from the liver for CON, C50, C100, and C150, respectively. Hepatic alpha-amino N uptake for all treatments greatly exceeded that required for the remaining urea-N release by the liver, suggesting that alpha-amino N may serve as a temporary means of storing excess N by liver between supplementation events. The pattern of net release or uptake of N metabolites between supplementation events requires further investigation. 相似文献
Two depth profiles of the osmium concentration and the 187Os/186Os isotopic ratio in the Indian Ocean showed that the osmium concentration seems to be unaltered by chemical or biological processes occuring in seawater; accordingly, osmium is conservative. These data were obtained from an experimental method that eliminated the problems related to osmium preconcentration. This method led to a new evaluation of the concentration of osmium in seawater; the mean concentration of osmium and the 187Os/186Os ratio are equal to 10.86 +/- 0.07 picograms per kilogram and 8.80 +/- 0.07, respectively. The results suggest the existence of an organocomplex that dominates the speciation of osmium in seawater. 相似文献
