Philip E. Vercoe

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In mature male sheep, the level of nutrition acutely influences the secretion of reproductive hormones. The mechanism involved is not fully understood but findings in humans and laboratory rodents would suggest a major role for leptin that is secreted from adipose tissue and then travels via the circulation to the central nervous system. Before we can begin(More)
The Butyrivibrio group comprises Butyrivibrio fibrisolvens and related Gram-positive bacteria isolated mainly from the rumen of cattle and sheep. The aim of this study was to investigate phenotypic characteristics that discriminate between different phylotypes. The phylogenetic position, derived from 16S rDNA sequence data, of 45 isolates from different(More)
In the present study, following the measurement of methane emissions from 160 mature ewes three times, a subset of twenty ewes was selected for further emission and physiological studies. Ewes were selected on the basis of methane yield (MY; g CH4/kg DM intake) being low (Low MY: >1 sd below the mean; n 10) or high (High MY: >1 sd above the mean; n 10) when(More)
Orexins exert their effects through two specific receptors (OX1R and OX2R) that have been found mainly in the brain and also in peripheral tissues of rats and humans. Here, we demonstrate expression of mRNA encoding for ovine OX1R and OX2R in central and peripheral tissues of sheep. Gene expression for orexin receptors in the hypothalamus and the preoptic(More)
The aim of this study was to identify ruminal bacteria that form stearic acid (18 : 0) from linoleic acid (cis-9,cis-12-18 : 2). One 18 : 0-producing isolate, P-18, isolated from the sheep rumen was similar in morphology and metabolic properties to 'Fusocillus' spp. isolated many years ago. Phylogenetic analysis based on nearly full-length 16S rRNA gene(More)
We measured in vitro anthelmintic activity in extracts from 85 species of Australian native shrub, with a view to identifying species able to provide a degree of worm control in grazing systems. Approximately 40% of the species showed significant activity in inhibiting development of Haemonchus contortus larvae. The most active extracts showed IC50 values(More)
Changes in food intake affect the reproductive axis in both sexes, and the nutritional signals involved and the sites that receive those signals are now beginning to be unravelled. Our studies have focussed on the mature male sheep, a model in which high food intake stimulates GnRH-LH pulse frequency for only 10-20 days but continues to promote testicular(More)
Immune-mediated scouring due to ingested parasite larvae is a major concern for sheep producers in Mediterranean climates. We investigated immune-mediated scouring in parasite-resistant Merino sheep in Australia. Forty-adult, parasite-resistant Merino rams were judged to be either susceptible or non-susceptible to immune-mediated scouring on the basis of(More)
The peri-parturient period is crucial for controlling worms as the acquired immunity of ewes is disrupted, resulting in an increase in faecal worm egg counts. Two hypotheses were tested in this experiment - that ewes bred for worm resistance would have lower faecal worm egg counts than unselected control ewes, during late pregnancy and lactation, under(More)
In mature male sheep and goats, changes in feed intake seem to have little effect on gonadal endocrine function but induce profound changes on sperm production. These outcomes are due to changes in size of the seminiferous tubules and in spermatogenic efficiency. Except with severe underfeeding, there are only minor changes in the endocrine function of the(More)