Quantification of hardware effects of an on-line Dual Energy X-ray Absorptiometry scanner when predicting lamb carcass composition.

An on-line Dual Energy X-ray Absorptiometry (DXA) scanner's tissue composition prediction precision and accuracy was tested across the entire height of the unit's detector, and the hardware was assessed for robustness by measuring X-ray photon intensity throughout production days. There was good precision when predicting the tissue composition of 5 different lamb fat and lean muscle mixtures across 3 different thicknesses (R2 = 0.93 to 0.98, RMSE = 3.18% to 5.83%), however was less precise at the greatest thickness of 200 mm (R2 = 0.59, RMSE = 11.4%). There was no significant difference in the prediction of tissue composition at 8 of the 9 detector positions, however the position at the perpendicular of the X-ray photon beam was significantly different, with a fat prediction error of -4%, although no lamb carcass is detected in this position during normal production. A significant upwards drift in X-ray photon intensity was found over the course of production, especially immediately after restarting the DXA scanner following a period of inactivity. This upwards drift may affect tissue composition predictions over the span of a production day if uncorrected.

Interactions between Ewes and Rams during Mating Can Be Used to Predict Lambing Dates Accurately, but Not Sire.

Ewes often lamb over extended periods so the level of nutrition during pregnancy and lambing may be suboptimal for ewes that conceived later during mating. Predicting lambing dates would allow cohorts of ewes with similar gestational ages to be managed more precisely to achieve targets for ewe nutrition, feed on offer, mob sizes and access to shelter to improve lamb survival. The interactions between ewes and rams during mating have been used to predict the time of oestrus and lambing dates successfully, but this has not been tested at a commercial scale. In this study, proximity sensors were used to measure interactions between inexperienced Merino ewes (n = 317) and experienced rams (n = 9) during a 27-day mating period under commercial production conditions. When the gestation length was assumed to be 150 days, 91% of lambing dates were predicted within ±6 days of the actual birth date of lambs and 84% of lambing dates were predicted within ±3 days. The use of proximity sensors during mating was an effective means of predicting lambing dates, and there was no significant difference in accuracy for single bearing verses multiple bearing ewes. However, DNA parentage data showed the ram corresponding with the maximum daily interactions ratio was the sire for only 16% of all progeny, suggesting they could not be used to indicate the sire of the progeny.

Sire Breed, Litter Size, and Environment Influence Genetic Potential for Lamb Growth When Using Sire Breeding Values.

Lamb growth can be optimised with genetic selection using sire Australian sheep breeding values, however, breeding value expression has been shown to be reduced with poor nutrition. It was therefore hypothesised that the genetic potential for lamb growth would also be reduced, where production factors such as multiple births limit growth. Live weights at birth, weaning, and post-weaning were collected from more than 18,000 lambs produced over five years and eight locations of the Sheep Cooperative Research Centre Information Nucleus Flock experiment, and the impact of environment, production factors, and genotype was determined using mixed effects regression. The genetic potential for lamb growth was moderated by environment, multiple births, and sire type (p < 0.05). Twin lambs achieved 76% of the expected weight gain at weaning and 58% post-weaning. For triplet lambs weight gains were drastically less at approximately 30% of the expected gain at the same time points. Lambs born to maternal sires consistently had the poorest response to genetic selection, achieving approximately half the expected weight gain. Hence, producers need to temper expectations for growth based on genetic selection, or employ mitigation strategies such as precision feeding, the use of alternate breeds, or place emphasis on the genetic merit of other desirable traits.

Consumer Perceptions of Meat Redness Were Strongly Influenced by Storage and Display Times.

Lamb (n = 79) meat colour was scored by 879 untrained consumers using a scale of 0 (brown) to 100 (red). This consumer colour score (CCS) was obtained on m. longissimus lumborum (loin) and m. semimembranosus (topside), stored for short (5-7 days), medium (33-35 days), and long periods (110-112 days) and a retail display time of up to 4 days. Consumers perceived topside to be less red initially and changed from red to brown more rapidly when stored for the long-storage period (p < 0.01). Whereas, the initial CCS of loin samples were similar across the storage periods (p > 0.05). CCS and the instrument measure oxy/met (reflectance of light at wavelengths 630 nm and 580 nm) had a low correlation coefficient of 0.33 (p < 0.01). The propensity for lamb growth and leanness indicated by sire breeding values for lamb weight, eye muscle depth, eye muscle fat depth, and loin intramuscular fat had varied and inconsistent effects on CCS. Therefore, even the selection on CCS.

Dual energy X-ray absorptiometry predicts lamb carcass composition at abattoir chain speed with high repeatability across varying processing factors.

An on-line Dual Energy X-ray Absorptiometry (DXA) scanner was used in an Australian abattoir to predict computed tomography (CT) determined composition % of fat, lean muscle and bone in lamb carcasses at chain speed. This study assessed the effect of spray-chilling on these estimates, as well as their repeatability over a 10-min period, and over a 72 h period. There was no prediction bias between the 15 spray-chilled and 15 non-spray-chilled carcasses. When repeat DEXA scans were undertaken across a 10-min period, there was a high level of repeatability for the prediction of CT Fat %. When repeat scans were conducted at 6 time points across a 72 h period the precision of the DXA prediction of CT Fat % of 30 carcasses remained high (R2 = 0.94, RMSEP = 1.20%), although small biases existed between time points (P < 0.01). These biases were minimised when the DXA scanner had been operational prior to experimentation, suggesting a 'warm-up' effect.

Extreme bilateral polydactyly in a wild-caught western grey kangaroo.

Polydactyly is a congenital malformation resulting from an autosomal dominant mutation manifesting as supernumerary digits of the hands or feet. It is most commonly reported in humans and domestic mammals, though there have also been isolated examples across a range of wild vertebrate species. Here we report a case of extremely unusual bilateral preaxial polydactyly on the pectoral limbs of a male western grey kangaroo (Macropus fuliginosus) from the South West region of Western Australia, in which two supernumerary digits were present on each manus. A supernumerary digit I on each manus was rudimentary in morphology without extrinsic muscular connections. However, supernumerary digit II present on each manus had fully developed extrinsic and intrinsic muscular connections, suggesting that these digits possessed normal function in flexion and extension. An alternative hypothesis is that the two supernumerary digits are both representatives of the most radial digit I, though this would then require the true digit I to have taken on the appearance of digit II by acquiring an additional phalanx and modified muscular attachments. The carpal bones exhibited a number of subtle differences in morphology when compared to normal pentadactyl individuals. The presence of a distal, rather than proximal, epiphysis on the first metacarpal was unexpected but further investigation suggested that this characteristic is perhaps more variable (in this species at least) than has been previously recognized. This case provides an unusual example to be considered within the broader context of limb development.

Effects of different ageing methods on colour, yield, oxidation and sensory qualities of Australian beef loins consumed in Australia and Japan.

This study investigated the effect of three ageing methods (dry, wet and stepwise wet-then-dry) and ageing time on pH, colour, yield, lipid and protein oxidation and eating quality of beef loins using Meat Standards Australia (MSA) sensory protocols with 900 and 540 consumers in Australia and Japan, respectively. Australian beef loins (Longissimus thoracis et lumborum) at four days post mortem were subjected to wet ageing (boneless; for 7, 21, 35 or 56 days), dry ageing (bone-in; for 35 or 56 days) or a wet-then-dry ageing method (bone-in; 21 days wet ageing followed by 35 days dry ageing). The pH was higher in dry aged than wet aged beef loins (P < .001). Instrumental measurement of surface colour of trimmed dry and wet aged steaks showed significant differences in a*, b* and hue angle. Weight loss was higher in dry aged primals (P < .001), however, total water content was similar among the two ageing methods (P = .934). Retail yield did not differ between 35 and 56 days dry aged primals. Lipid (TBARS) and protein (total carbonyl content) oxidation between the dry and wet aged samples differed depending on the ageing time. When comparing the wet-then-dry and 56 days dry aged samples, only pH and retail yield differed. Australian and Japanese consumers rated dry aged steaks significantly higher (P < .001) than the wet aged counterparts for tenderness, juiciness, flavour, overall liking and weighted palatability scores. The wet-then-dry steaks were also rated higher than the 56 days wet aged steaks for flavour, overall liking and palatability within the Japanese sensory panels. The Japanese consumers also consistently rated all MSA sensory attributes lower (P < .001) than the Australian consumers. The results from this study show dry ageing provides a value adding opportunity for the meat industry in both domestic and export markets.

Comparison of survival after surgical or medical treatment in dogs with a congenital portosystemic shunt.

OBJECTIVE: To compare survival of dogs with a congenital portosystemic shunt (CPSS) that received medical or surgical treatment. DESIGN: Prospective cohort study. ANIMALS: 126 client-owned dogs with a single CPSS. PROCEDURES: Dogs were examined at 1 of 3 referral clinics, and a single CPSS was diagnosed in each. Dogs received medical or surgical treatment without regard to signalment, clinical signs, or results of hematologic or biochemical analysis. Survival data were analyzed via a Cox regression model. RESULTS: During a median follow-up period of 579 days, 18 of 126 dogs died as a result of CPSS. Dogs treated via surgical intervention survived significantly longer than did those treated medically. Hazard ratio for medical versus surgical treatment of CPSS (for the treatment-only model) was 2.9 (95% confidence interval, 1.1 to 7.2). Age at CPSS diagnosis did not affect survival. CONCLUSIONS AND CLINICAL RELEVANCE: Both medical and surgical treatment can be used to achieve long-term survival of dogs with CPSS, although results of statistical analysis supported the widely held belief that surgery is preferable to medical treatment. However, the study population consisted of dogs at referral clinics, which suggested that efficacy of medical treatment may have been underestimated. Although surgical intervention was associated with a better chance of long-term survival, medical management provided an acceptable first-line option. Age at examination did not affect survival, which implied that early surgical intervention was not essential. Dogs with CPSS that do not achieve acceptable resolution with medical treatment can subsequently be treated surgically.