Comparison of models for estimation of genetic parameters for mature weight of Hereford cattle

Genetic parameters of mature weight are needed for effective selection and genetic evaluation. Data for estimating these parameters were collected from 1963 to 1985 and consisted of 32,018 mature weight records of 4,175 Hereford cows that were in one control and three selection lines that had been selected for weaning weight, for yearling weight, or for an index combining yearling weight and muscle score for 22 yr. Several models and subsets of the data were considered. The mature weight records consisted of a maximum of three seasonal weights taken each year, at brand clipping (February and March), before breeding (May and June), and at palpation (August and September). Heritability estimates were high (0.49 to 0.86) for all models considered, which suggests that selection to change mature weight could be effective. The model that best fit the data included maternal genetic and maternal permanent environmental effects in addition to direct genetic and direct permanent environmental effects. Estimates of direct heritability with this model ranged from 0.53 to 0.79, estimates of maternal heritability ranged from 0.09 to 0.21, and estimates of the genetic correlation between direct and maternal effects ranged from -0.16 to -0.67 for subsets of the data based on time of year that mature weight was measured. For the same subsets, estimates of the proportions of variance due to direct permanent environment and maternal permanent environment ranged from 0.00 to 0.09 and 0.00 to 0.06, respectively. Using a similar model that combined all records and included an added fixed effect of season of measurement of mature weight, direct heritability, maternal heritability, genetic correlation between direct and maternal effects, proportion of variance due to direct permanent environmental effects, and proportion of variance due to maternal permanent environmental effects were estimated to be 0.69, 0.13, -0.65, 0.00, and 0.04, respectively. Mature weight is a highly heritable trait that could be included in selection programs and maternal effects should not be ignored when analyzing mature weight data.     

Matrix metalloproteinase activity in tumor, stromal tissue, and serum from cats with malignancies

Matrix metalloproteinases (MMPs) are enzymes that play key roles in angiogenesis, tumor invasion, and metastasis in a wide variety of species. The purpose of this study was to evaluate pro and active MMP 2 and 9 concentrations in tumor, normal stromal tissue, and serum from tumor-bearing cats. We hypothesized that serum concentrations of pro and active forms of MMPs 2 and 9 would be predictive of MMP concentrations in tumor tissue and that these MMP concentrations would correlate with the histopathologic grade of the malignancies. Pro and active forms of MMPs 2 and 9 were determined by gelatin zymography and subsequent computerized densitometry from tumor and nearby stromal tissue and serum from 49 cats with various malignancies. The serum concentrations of MMPs from these tumor-bearing cats were compared with serum concentrations of MMPs from 44 normal cats of similar age and gender. Measurable concentrations of MMPs 2 and 9 were found within tumor, stromal, and serum samples. Mean concentrations of total pro and active MMPs 2 and 9 within tumor tissue were significantly higher (P values <.0001, .0031, <.001, and .0064, respectively) when compared with stromal tissue from the same animals. Serum MMP concentrations from tumor-bearing cats were higher than those from normal cats. Poor correlation was found between serum MMP concentrations and tissue MMP concentrations of increasing histologic grades of malignancies.     

Effects of dietary flaxseed oil supplementation on equine plasma fatty acid concentrations and whole blood platelet aggregation

An 18-week feeding trial was performed to investigate the effects of an omega-3 (n-3) fatty acid-enriched ration on plasma fatty acid concentrations and platelet aggregation in healthy horses. Flaxseed oil served as the source of the n-3 fatty acid alpha-linolenic acid (ALA). Twelve horses were fed dietary maintenance requirements using a complete pelleted ration (80%) and timothy grass hay (20%) for a 2-week acclimation period before being randomly assigned either to a treatment (group 1) or control (group 2) group. Group 2 horses (n = 6) were fed the diet described in the acclimation period, whereas group I horses (n = 6) were fed a 10% flaxseed oil-enriched complete pellet (80%) and grass hay (20%). Biological samples and physical measurements were collected at one point during the acclimation period (week 0) and every 4 weeks thereafter (weeks 4, 8, 12, and 16). Body weight, CBC (including platelet count), plasma fibrinogen. electrolyte (Na, K, and Cl) concentrations, and biochemical profile enzyme activities (aspartate aminotransferase, alkaline phosphatase, gamma-glutamyltransferase, and creatine kinase) did not change markedly with diet. Platelet aggregation was not altered by the supplementation of flaxseed oil in these healthy horses, although increases in plasma cis-polyunsaturated 18-carbon fatty acids C18:3; n-3 (ALA) and C18:2; n-6 (linoleic acid), biologically active C20:5; n-3 (eicosapentaenoic acid [EPA]), and malondialdehyde (MDA) were evident. There were no marked decreases in C20:4; n-6 (arachidonic acid [AA]) or increases in C22:6; n-3 (docosahexaenoic acid [DHA]), signifying that flaxseed oil may have had a high percentage of omega-6 (n-6) fatty acids as well as n-3 fatty acids, and this relatively high n-6: n-3 fatty acid ratio may have affected the biochemical effect of n-3 fatty acids. In healthy horses supplemented with flaxseed oil, platelet aggregation was not altered, which may have been due to the limited biologic effect in healthy subjects or the inability of flaxseed oil to induce the necessary biochemical effect of replacing n-6 fatty acids with n-3 types.     

Effects of time and concentration on mortality of phosphine-resistant Sitophilus oryzae (L) fumigated with phosphine

The effects of exposure period and phosphine concentration on mortality of susceptible and resistant Sitophilus oryzae (L) were investigated. Although S oryzae is one of the world's most serious pests of stored grain there are few data on the practical significance of phosphine resistance in this species. The strains investigated were an Australian susceptible strain, a homozygous resistant strain exhibiting a level of resistance common in Australia and an unselected field strain from China with a much stronger resistance. Fumigations were carried out at 25 degrees C on adults and mixed-age cultures. For adults of all three strains and mixed-age cultures of the susceptible and resistant Australian strains, the relationship between concentration and time could be described by equations of the form Cnt = k. In all cases n < 1, indicating that time was a more important variable than concentration. In all fumigations of adults the resistant strains were harder to kill than the susceptible strain. However, in fumigations of mixed-age cultures, which contained the tolerant pupal stage, the difference between susceptible and resistant strains was more pronounced at lower concentrations than higher concentrations. For example, at 0.02 mg litre-1 the estimated LT99.9 for mixed-age cultures of the Australian resistant strain (27 days) is 3.4 times that of the susceptible strain (8 days), but at 1 mg litre-1 there is no difference between the two strains (4 days). Limited data on the Chinese resistant strain supported this finding. Twenty-three days exposure at 0.02 mg litre-1 had no effect on mixed-age cultures of this strain, but there were no survivors after 5 days exposure to 1 mg litre-1.     

Initial results of genomic scans for ovulation rate in a cattle population selected for increased twinning rate

Genomic scans were conducted with 273 markers on 181 sires from a cattle population selected for increased twinning rate to identify chromosomal regions containing genes that influence ovulation rate. Criteria used for selecting markers were number of alleles, ease of scoring, and relative position within linkage group. Markers were multiplexed or multiple-loaded on the gels to reduce the costs and labor required to obtain genotypic data. This approach reduced the number of gels by 45% when compared with running each marker independently. Male animals selected for the genomic scan sired the majority of the population. A modified interval analysis was used in a granddaughter design to compare effects of each allele within sire for 10 different sire families. The midparent deviation of the son's estimated breeding value for ovulation rate was used as the phenotype. Forty-one potential peaks were identified with a nominal significance level < or = 0.05. The 10 peaks with the highest significance levels (P < 0.02) were selected for further analysis. Markers were genotyped across daughters of the sire where nominal significance was found for each of the 10 peaks. One peak (BTA5, relative position 40 cM) was found to be nominally significant in the daughters. The nominal significance levels were P = 0.01 for the sons (n = 32) and P = 0.02 for the daughters (n = 94) of sire 784403. A combined genomewide significance value (P = 0.07) was calculated that accounted for the 10 analyses with sons and the 10 analyses with daughters. These results strongly suggest that this region contains a gene(s) that is involved in the follicular recruitment and development process.     

Effects of food withdrawal and transport on 5- to 10-day-old calves

The effects of food withdrawal for 30 hours and transport for up to 12 hours on 5- to 10-day-old calves were determined by monitoring plasma concentrations of glucose, beta-hydroxybutyrate, urea, lactate and creatine phosphokinase. In addition gamma-glutamyl transferase activity, packed cell volume, total plasma protein concentration, bodyweight and rectal temperature were recorded. Food withdrawal for 30 hours caused hypoglycemia but calves maintained normothermia and although their beta-hydroxybutyrate level increased indicating lipid mobilisation, the changes in blood urea level were minimal indicating low amino acid catabolism. When calves were transported for 12 hours in addition to having food withdrawn for 30 hours, they remained normoglycemic for six hours longer than non-transported calves, probably due to an effect of muscular activity during bracing against truck movements. Stocking calves at a lower density during transport apparently had a beneficial effect, as calves were able to lie down throughout the journey and therefore produced a similar metabolic profile to resting, non-transported animals. Transport and food withdrawal had no obvious effects on calf hydration. The results of this study suggest that food withdrawal for up to 30 hours and transport for up to 12 hours had no detrimental effects on the metabolism of healthy and clinically normal calves. With correct feeding regimes and transport protocols, welfare compromise in young, healthy calves being transported for up to 12 hours can be minimised when they are slaughtered within 30 hours of the start of transport.     

Renal transplantation in cats

Feline renal transplantation can offer long-term survival with a normal quality of life for cats with renal failure. However, it is important to remember that renal transplantation is a treatment option and not a cure. Renal transplantation is never performed on an emergency basis or prophylactically. Feline renal transplantation requires special microvascular instruments and an operating microscope. Careful patient selection and perioperative monitoring have improved the success rate. The new microemulsified form of cyclosporine is recommended for immunosuppression. As survival times have steadily improved, long-term complications, such as diabetes and neoplasia, are now being recognized.     

Pharmacokinetics of ketoprofen in the green iguana (Iguana iguana) following single intravenous and intramuscular injections.

The nonsteroidal antiinflammatory drug ketoprofen (KTP) is a commonly used antiinflammatory and analgesic agent in reptile medicine, but no studies documenting its pharmacokinetics in this species have been published. Ketoprofen was administered as a racemic mixture to green iguanas (Iguana iguana) intravenously (i.v.) and intramuscularly (i.m.) at 2 mg/kg. Pharmacokinetic analyses were performed and indicated that ketoprofen in iguanas administered by the intravenous route has a classical two-compartmental distribution pattern, a slow clearance (67 ml/ kg/hr) and a long terminal half-life (31 hr) compared to ketoprofen studies reported in mammals. When delivered by the intramuscular route, bioavailability was 78%. These data indicate the daily dosing that is generally recommended for reptile patients, as an extrapolation from mammalian data, may be more frequent than necessary.     

The Effect of Levothyroxine Treatment on Resting Energy Expenditure of Hypothyroid Dogs

Thirty adult, client-owned dogs were diagnosed with hypothyroidism based on history, physical examination findings, hematologic and biochemical abnormalities, thyrotropin (TSH) response testing, endogenous canine thyrotropin (cTSH) concentration, or both, and total serum thryoxine concentration. All dogs received levothyroxine (L-thyroxine) at an initial dose of 22 μg/kg PO sid in either a tablet (13 dogs) or chewable form (17 dogs). Energy expenditure of each dog during apparent rest was estimated with an open-flow indirect calorimetry system by determining the rates of carbon dioxide production and oxygen consumption. Energy expenditure of apparent rest (EE) was lower in untreated hypothyroid dogs compared with reference values for EE. After treatment with L-thyroxine, EE of the hypothyroid dogs was significantly ( P < .05) higher than pretreatment values.