Effect of Kisspeptin on Regulation of Growth Hormone and Luteinizing Hormone in Lactating Dairy Cows

Kisspeptin (KP),a neuroendocrine regulator of reproduction,is hypothesized to be an integrator of metabolism and hormones critical to the regulation of reproduction.Lactation is associated with enhanced growth hormone (GH) responsiveness and reduced fertility.Our study was designed to determine the effects of lactation on KP-stimulated GH and luteinizing hormone (LH) secretion.Five nonlactating and five lactating dairy cows were used in the study.Experiments were conducted with lactating cows at weeks 1,5 and 11 after parturition.The experimental treatments (saline and KP [ 100 and 400 pmol/kg body weight] ) were given intravenously and blood was collected and plasma was stored until later assay to determine concentrations of GH,LH,progesterone and non-esterified fatty acids.We found that neither dose of KP stimulated an increase in GH secretion.The low dose of KP increased (P ＜0.05)LH concentrations only in lactating cows.The higher dose of KP elicited an increase in circulating LH concentrations in both lactating and non-lactating cows.The lower dose of KP increased ( P ＜ 0.05 ) the area under the curve for LH only in cows during week 5 of lactation,and the area under the curve of LH following the highest dose of KP was greater ( P ＜ 0.05 ) in cows during week 5 of lactation than that for the other groups of cows.In summary,lactation status and stage of lactation did not change the sensitivity of the GH system to KP.However,an effect of stage of lactation on KP-stimulated LH secretion was detected in the dairy cows.Study of the KP system during lactation in dairy cows may provide critical insights into the mechanisms for lactation-associated changes in the reproductive axis.     

Facial swelling and discharging lesions associated with abnormalities of the mandible in kunekune pigs

Abstract

CASE HISTORIES: Four adult kunekune pigs developed facial swelling at the base of the right ear that ruptured and discharged food material. A further six pigs that had similar clinical signs were reported by members of the New Zealand Kunekune Association who responded to an email survey, one of which was confirmed by post-mortem examination.

CLINICAL FINDINGS: Inside the mouth of each pig there was an opening at the junction of the body and ramus of the mandible just lateral to the most caudal visible molar that was impacted with masticated feed. The food packed into the mandible resulted in infection and progressive erosion of the medullary cavity of the bone until it reached the ramus where it eroded through the lateral cortex. The feed material then tracked through the soft tissues to form a subcutaneous abscess, which eventually ruptured resulting in a draining lesion. In Case 2, which had had the lesion for 2 years, the cavity in the mandible was lined with mucosa that had healed to the skin to produce a fistula. In all four pigs there was also a lesion in the left side of the mandible that was not as developed as that on the right side.

DIAGNOSIS: The facial swellings were produced by feed material that had impacted into the mandible through an opening immediately caudal to the cheek teeth and then emerged through one or more lesions in the lateral aspect of the ramus of the mandible.

CLINICAL RELEVANCE: Although it has not been previously reported, anecdotal reports and our survey suggest that this condition may occur relatively frequently in kunekune pigs. It should be considered as a differential diagnosis for facial swellings and discharging lesions in these animals.     

Osseous lesions resembling vaccine-site sar comas in two cats

Extract

Lytic lesions with microscopic features similar to those of vaccine-site sarcomas were diagnosed in the distal femur of two young neutered male cats, one a 20-month-old Birman and the other an 18-month-old domestic short-hair (DSH). Radiographically, there was extensive destruction of trabecular and cortical bone in the metaphysis and/or epiphysis of the distal femur. The DSH cat also had angular deformity of the distal femur due to asymmetrical involvement of the physis. Histologically, the lesions in both cats consisted of dense, interwoven bundles of fibrous connective tissue, amongst which there were variable numbers of plump malignant mesenchymal cells, often with very large, hyperchromatic nuclei and irregularly shaped nucleoli. Several focal aggregates of small lymphocytes were present in both tumours. Although neither cat had apparently been vaccinated in the hindlimb it is possible that the tumours had been triggered by injection of some other irritant material.     

Effects of initial and extended exposure to an endophyte-infected tall fescue seed diet on faecal and urinary excretion of ergovaline and lysergic acid in mature geldings

Abstract

AIM: To determine the amount of ergovaline and lysergic acid retained or excreted by geldings fed endophyte-infected seed containing known concentrations of these alkaloids, and the effects of exposure time on clinical expression of toxicosis.

METHODS: Mature geldings (n=10) received diets containing either endophyte-free (E-) or endophyte-infected (E+) tall fescue seed during three experimental phases. The first phase (Days ?14 to ?1) was an adaptation phase, to allow all horses to adapt to a diet containing E- tall fescue seed. The second (Days 0 to 3) was the initial exposure phase to E+ tall fescue seed, used for the delivery of ergovaline and lysergic acid at 0.5 and 0.3 mg/kg of diet, respectively, to test the initial effects of exposure on routes and amounts of elimination of alkaloid. During this phase, half the geldings were exposed to an E+ diet while the rest served as controls by remaining on the E- diet. Once assigned to treatments, geldings remained on the same diet through the third phase (Days 4 to 21), which served as the extended exposure phase. Total outputs of faeces and urine were collected within each phase, to determine retention of ergovaline and lysergic acid and nutrient digestibility. Serum was collected weekly and analysed for activities of enzymes and concentrations of prolactin. Bodyweights (BW) and rectal temperatures were recorded weekly.

RESULTS: BW, rectal temperature, enzyme activities and concentrations of prolactin in serum, and nutrient digestibility were not affected by treatment. Total intake of ergovaline by geldings on the E+ diet was 3.5 and 3.6 (SE 0.20) mg/day, and 2.1 and 2.3 (SE 0.11) mg/day were not accounted for in initial and extended phases, respectively. Lysergic acid was excreted in the urine (4.0 and 4.9 (SE 0.97) mg/day) and faeces (2.5 and 2.7 (SE 0.35) mg/day) at greater amounts than that consumed (2.0 and 1.9 (SE 0.09) mg/day) during the initial and extended exposure phases, respectively. Animals exposed to E+ seed for a period of 20 days appeared to excrete more (1.5 vs 1.2 mg/day; SE 0.08; p=0.03) ergovaline in the faeces than those exposed for only 4 days.

CONCLUSIONS: Exposure time to the ergot alkaloids had a limited effect on the route of elimination or the amounts of ergovaline or lysergic acid excreted by horses. The primary alkaloid excreted was lysergic acid, and urine was the major route of elimination. These data will aid future research to improve animals′ tolerance to toxic endophyte-infected tall fescue.     

Effects of cimetidine and ranitidine on basal gastric pH, free and total acid content in pigs

The effects of intramuscular administration of multiple doses of cimetidine and ranitidine on basal gastric pH, free and total acid content from young adult pigs were studied. Cimetidine (4.5 mg kg-1, four times a day, intramuscularly, for three days) significantly (P less than 0.05) raised the basal gastric pH above 3.5 with a simultaneous reduction in free acid content at two, three and 26 hours after the administration of the eighth dose. Ranitidine (0.75 mg kg-1, four times a day, intramuscularly, for three days) significantly (P less than 0.05) raised the basal gastric pH above 3.5 with a concomitant reduction in free acid content at three and 38 hours after the administration of the eight dose. Neither cimetidine nor ranitidine had any significant effects on total acid content. These results confirm that the pig is a basal acid secretor and that the pharmacodynamics and pharmacokinetics of cimetidine and ranitidine in pigs might be different from those in humans.     

STAINING SPERM FOR VIABILITY ASSESSMENT

Assessing the functional capacity of sperm in vitro is of particular interest to the artificial insemination industry in order to select sires with the best fertilizing capacity. Early efforts to evaluate semen dating into the past century were based on microscopical observation of motility and abnormal morphology. Frequently, eosin stain was used to quantify live and dead sperm while giemsa stain was used for morphological evaluation. These methods along with visual inspection of the semen were useful but their repeatability was questionable. The advent of fluorescent staining improved microscopical evaluation of sperm, however, one of the major drawbacks remains, that is that one can only evaluate 100 or 200 sperm per sample. The advent of flow cytometry in the early 1970's and the development of new stains has led to more accurate means of assessing sperm viability. Fluorescein diacetate (FDA), carboxyl-fluorescein diacetate (CFDA) in combination with propidium iodide (PI) were applied to flow cytometric assessment in the early 1980's. With flow cytometry several thousands of sperm can be analyzed quickly and without detriment. Staining sperm with FDA, CFDA and PI is useful but is time dependent leading to deterioration of the sample which can alter results. Hoechst stain, 33342 and 33258 were classed as vital stains in 1979. Hoechst 33342, a highly permeable fluorescent stain became prominent for use to differentiate X from Y sperm based on binding in a stoichiometric manner to DNA. Hoechst 33258, a useful exclusion dye, will only stain sperm with lysed membranes. More recently a new membrane permeant dye, SYBR-14 has been used in combination with PI and is characterized by entering only those cells possessing a membrane potential. It shows a very high correlation with living sperm and a highly negative correlation with PI stained dead sperm. Initial studies show that the SYBR-14/PI combination is time insensitive, which allows one to evaluate semen outside of a strict time regimen. The use of CTC and FITC-PSA to ascertain the condition of the acrosome, using both the fluorescent microscopy and flow cytometry has proven to be a very useful tool. Finding one single test to evaluate the fertilizing potential of sperm continues to be elusive. However, using several tests, in combination, such as motility, acrosomal integrity, and a fluorescent assessment of membrane integrity would add significant credibility to estimating sperm function.     

Preliminary study of joint disease in poultry by the analysis of synovial fluid

Samples of synovial fluid and synovial membrane were obtained from the hock joints of several groups of broilers, including lame birds and two strains of broilers raised on different feeding regimens and given different drug treatments (carprofen or placebo). There were more significant differences between the groups on the basis of the analysis of the synovial fluid samples than the synovial membrane samples. Experimental birds fed ad libitum had the highest median red blood cell counts and median ghost cell counts of all of the groups, but there were no differences between the groups in the thickness of the synovial lining cell layer or the degree of cellular infiltrate in the synovial membrane. The synovial fluid from the broilers and lame birds fed ad libitum was more turbid, suggestive of intra-articular pathology, and the large numbers of heterophils in samples from the lame birds indicated an inflammatory arthropathy. The birds fed ad libitum which were treated with carprofen had more cells in the synovial fluid than the birds given the placebo. A large number of the samples of synovial fluid from the ad libitum-fed broilers contained blood.