Gonadotrophin-releasing hormone treatment in cattle: a meta-analysis of the effects on conception at the time of insemination

SUMMARY Data from 40 trials described in 27 published papers were analysed by meta-analysis (pooling of data from numerous trials into a single analysis) to evaluate the effects of injecting gonadotrophin-releasing hormone (GnRH) In cattle at the time of Insemination on the risk of pregnancy. A total of 19 019 cows were involved In these studies. Analyses were stratified by trial and by the effects of dose of GnRH, type of GnRH and Insemination number (first, second or third and greater). Mantel-Haenszel analysis revealed that use of GnRH at Insemination significantly Increased the overall risk of pregnancy by 12.5% In treated cows (P < 0.05). However, Increases In risk of pregnancy were greatest (22.5%) when repeat breeders were treated. Results for use of GnRH or analogue at first service were similar, with Increased risks of pregnancy in treated cows of 5.2 and 8.0%, respectively. The risk of pregnancy tended to be higher (11.1%) when the dose of GnRH was 250 μg and when used at second Insemination (9.9%). The analyses demonstrated that while treatment at Insemination with GnRH and GnRH analogues Increased conception rates In dairy cattle, some variation In study results was attributable to the number of Inseminations after calving at which GnRH Is administered. Further efforts should be made to determine characteristics of populations of cows that have good fertility responses to GnRH and to determine the mode of action of GnRH in Increasing fertility. Meta-analysis proved to be a useful technique for evaluating the apparently conflicting results from trials and in evaluating the effect of factors such as Insemination number, dose and type of GnRH on responses to treatment.     

Effects of supplemental tallow on rumen ciliated protozoa in feedlot cattle

Ruminal samples were collected at slaughter from 98 steers consuming a high-grain diet and receiving either no fat, or 2, 4, 6, or 8% supplemental tallow. Tallow supplementation tended (P = 0.11) to increase average ciliated protozoan numbers, however, the occurrence of defaunated animals was higher in the 8% fat treatment than in the control group. Entodinium spp. were the only protozoans that survived in all treatments, and total numbers ranged up to 3.2 x 10(6)/g of ruminal contents. Although increasing tallow supplementation induced a defaunating effect in many animals, the response was unpredictable and protozoa occasionally proliferated irrespective of fat level.     

Congenital hypothyroidism in Scottish Deerhound puppies

Two Scottish Deerhound puppies had clinical and pathological features consistent with the diagnosis of congenital non-goitrous hypothyroidism. They were from separate litters, but were the progeny of the same sire and dam. The puppies were smaller, had shorter limbs and shorter, broader heads than their littermates. They also had histories of weakness, difficulty in walking and somnolence. A characteristic radiographic feature was the absence of epiphyseal growth centres. Both had depressed serum thyroxine (T4) levels and one did not respond to exogenous thyroid stimulating hormone. On necropsy, the thyroid glands were small, the follicles varied in size and contained little or no colloid. The adenohypophysis contained many cells with markedly vacuolated cytoplasm. It is suggested that the clinicopathological pattern is the result of a primary thyroid abnormality. Possible mechanisms include either primary thyroid hypoplasia or an unresponsiveness to thyroid stimulating hormone.     

Ruminal evacuation's effect on microbial activity and ruminal function

The influence of evacuating, mixing and returning ruminal contents on microbial populations, volatile fatty acid (VFA) concentrations and liquid flow rate was investigated with four ruminal-cannulated Hereford steers (247 kg avg wt). Ruminoreticular contents were sampled, then completely removed, mixed for 5 min and returned to the rumen. Subsequent samples were taken immediately, 1 h and 4 h later. Non-evacuated steers were sampled at identical time intervals either 1 d before or after evacuation. Averaged over time, there was no significant difference between evacuated and non-evacuated steers in total anaerobic, cellulolytic and facultative bacteria, protozoa, oxidation-reduction potential, VFA concentrations, and liquid flow rates. There were no treatment X time interactions and, except for holotrich protozoa and VFA, no differences from time of sampling. Ruminal evacuation does not appear disruptive to anaerobiosis or detrimental to ruminal microorganisms and digestive processes.     

The chemistry of water on alumina surfaces: reaction dynamics from first principles

Aluminas and their surface chemistry play a vital role in many areas of modern technology. The behavior of adsorbed water is particularly important and poorly understood. Simulations of hydrated alpha-alumina (0001) surfaces with ab initio molecular dynamics elucidate many aspects of this problem, especially the complex dynamics of water dissociation and related surface reactions. At low water coverage, free energy profiles established that molecularly adsorbed water is metastable and dissociates readily, even in the absence of defects, by a kinetically preferred pathway. Observations at higher water coverage revealed rapid dissociation and unanticipated collective effects, including water-catalyzed dissociation and proton transfer reactions between adsorbed water and hydroxide. The results provide a consistent interpretation of the measured coverage dependence of water heats of adsorption, hydroxyl vibrational spectra, and other experiments.     

A survey of bone integrity from cull sows in Ireland

The objective of this study was to examine the differences in sow metacarpal properties through various parities and to compare the incidence of locomotory problems between stalled and loose-housed sows. Metacarpals (n = 110) of sows from six farms were collected at slaughter and stored at -20°C. Bones from one forelimb of sows in stalls (n = 36) and loose-housed (n = 20) were collected and their articular surfaces examined for Osteochondrosis Dissecans (OCD), these sows were also scored for lameness pre-slaughter. Metacarpals were CT scanned for cross sectional area and moment of inertia. Cylindrical sections from the diaphysis were used for mechanical testing and calculating bone strength indices. The results show there was little change in bone mineral status throughout the range of parities examined and overall metacarpal integrity was not compromised by multiple production cycles. There were no differences detected in the incidence of lameness or joint pathology between housing systems.     

Noise evaluation techniques for apartments and condominiums

Prospective buyers of condominium apartments are in need of a check list to assist them in evaluating the acoustical performance of the units prior to purchase. This paper discusses the sources of noise transmission path and provides a noise evaluation check list.