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Forty LW × L pigs (20 boars and 20 gilts) (51.1 ± 0.41 kg) were allocated to a 2 × 2 × 2 factorial design with the respective factors being supplemental organic iron (Fe, 0 and 500 mg/kg), inulin (In, 0 and 50 g/kg) and sex (boars and gilts). After 5 weeks the animals were transported to an abattoir before slaughter and collection of samples. Serum iron was increased by supplemental Fe (28.4 v. 30.9 μmol/L, P = 0.05), although there was an interaction (P = 0.03) such that pigs fed diets with In had lower serum Fe concentrations than those without In (26.8 v. 32.3 μmol/L). Boars had lower (P < 0.01) haemoglobin (116 vs 125), haematocrit (36.7 v. 39.7%) and erythrocyte (6.6 v. 7.1 × 106/mL) concentrations than gilts. Dietary In increased liveweight gain (795 v. 869 g/d, P < 0.02) and carcass weight (62.9 v. 65.2 kg, P < 0.02). Dietary Fe or In supplementation did not improve muscle Longissimus thoracis et lumborum (LTL) total Fe concentration (P > 0.05). Muscle non-heme Fe concentration was higher in Fe-supplemented pigs (P < 0.04) and gilts (P < 0.05) than their counterparts. Muscle heme Fe concentration was greater (3.04 vs 2.51, P < 0.05) in boars than in gilts. The LTL marbling score was greater (P < 0.01) for In-supplemented pigs, and the response was more notable when Fe and In were fed together. These data show that dietary supplementation of Fe increased serum Fe and muscle non-heme Fe concentrations. Supplementation of In at 5% in the diet of finisher pigs improved liveweight gain and the marbling score of pork. [ABSTRACT FROM AUTHOR]

Abstract: Exogenous porcine somatotropin (pST) treatment consistently improves growth performance and reduces fat deposition in pigs, and it is hypothesized that one component of the mechanism is through altering the sensitivity and/or responsiveness to insulin. Therefore, a study was conducted to investigate the effect of pST treatment on whole-body glucose metabolism in response to varying doses of insulin. Eight barrows were surgically prepared with indwelling catheters and randomly assigned to one of two treatment groups (0 or 120 μg pST/kg BW · d) for 13 d. Whole-body glucose kinetics were measured during infusion of [6-3H]-glucose under basal conditions and during hyperinsulinemic-euglycemic clamps at various insulin infusion rates (7, 28, and 140, and 14, 70, and 280 ng insulin/kg BW · min) and alterations in the dose–response parameters were calculated with nonlinear regression. Treatment with pST increased basal plasma concentrations of glucose (36%; P = 0.005), insulin (276%; P = 0.001), and NEFAs (177%; P = 0.01) and decreased the rate of glucose disappearance (−59%; P = 0.001). The responsiveness (maximum response) for steady state glucose infusion rate to maintain glycemia was not altered by pST (112 vs 106 μmol/min · kg; P = 0.78), whereas the sensitivity (effective dose at 50% of maximum response) was increased almost 7-fold (1.3 vs 8.7 ng/mL; P = 0.027). Similar responses were observed for rate of glucose disappearance and insulin-dependent glucose utilization. Therefore, pST-induced insulin resistance with regard to whole-body glucose uptake is due to a reduced sensitivity to insulin, rather than a change in responsiveness. [Copyright &y& Elsevier]

Abstract: Metabolic processes in muscle tissue in vivo result in the production of reactive oxygen species and oxidative compounds including superoxide anions and nitric oxide (NO). Reactive oxygen species can react with both lipids and proteins and often have deleterious effects, contributing to the onset of ageing and senescence as well as cell death. Nitric oxide (NO) is a free radical that is constantly produced or released throughout the body by diverse tissues and is known to influence proteolytic activity in human and rodent skeletal muscle as well as being involved in regulation of calcium homeostasis in the muscle cell. The influence of nitric oxide on development of meat tenderness has been studied through postmortem manipulation and also through in vivo studies. The effect of NO on meat tenderness is postulated to be via its regulatory effects on the proteins calpain, cathepsins, ryanodine receptor channel in the sarcoplasmic reticulum (SR) and the sarcoplasmic–endoplasmic release calcium ATPase in the SR. NO is an oxidant although the effects of NO on effector proteins can be distinguished from a direct oxidation reaction. The onset of oxidation in meat postmortem is well known to produce off-odours, discolouration and unacceptable flavours associated with rancidity. Oxidation during the immediate postmortem period appears to inhibit tenderisation during ageing, probably through an inhibitory effect of oxidation on the calpain enzyme. Oxidation of muscle tissue occurring as a result of availability of oxygen during modified atmosphere packaging may also have deleterious consequences for tenderness development during storage of meat prior to retail display. In conclusion, it is proposed that postmortem meat tenderisation is influenced by skeletal muscle’s release of NO pre-slaughter and the oxidation of proteases postmortem. This proposal is compatible with the existing tenderness model and will hopefully assist in increasing the accuracy of prediction of meat tenderness. Future directions for research are discussed. [Copyright &y& Elsevier]

Abstract: A number of technologies that increase feed efficiency and lean tissue deposition while decreasing fat deposition have been developed in an effort to improve profitability of animal production. In general, the mode of action of these metabolic modifiers is to increase muscle deposition while often simultaneously reducing fat deposition. However, there have been some concerns that the focus on increasing production efficiency and lean meat yield has been to the detriment of meat quality. The aim of this review is to collate data on the effects of these metabolic modifiers on meat quality, and then discuss these overall effects. When data from the literature are collated and subject to meta-analyses it appears that conservative use of each of these technologies will result in a 5–10% (0.3–0.5kg) increase in shear force with a similar reduction in perception of tenderness. However, it should be borne in mind that the magnitude of these increases are similar to those observed with similar increases in carcass leanness obtained through other means (e.g. nutritional, genetic selection) and may be an inherent consequence of the production of leaner meat. To counter this, there are some other metabolic factors and dietary additives that offer some potential to improve meat quality (for example immuncastration) and it is possible that these can be used on their own or in conjunction with somatotropin, approved β-agonists, anabolic implants and CLA to maintain or improve meat quality. [Copyright &y& Elsevier]

An experiment was conducted to compare behaviour, in particular social and feeding behaviour, and consequently growth performance of group-housed entire and castrated male pigs during the finisher stage of production. Three treatments: (1) entire males, (2) immuno-castrated males, treated with Improvac® at 14 and 18 weeks of age, and (3) surgically-castrated males, castrated at 14-days old, were compared to assess whether castration affected feeding and social behaviours. Twelve groups of 15 male pigs were formed at 14 weeks of age (47.1±5.50 kg). Pigs had ad libitum access to pelleted, commercial feed from two single space feeders per pen. Pig behaviour and feeder utilisation were compared during 24-h periods at 17 and 21 weeks of age, using time-lapse video recording. At 17 weeks, entire males and immuno-castrated males were more active (P<0.05) than surgical-castrated males (21.9, 19.8 and 16.1% of 24 h), but at 21 weeks there were no differences among the treatments (pooled mean 16.4% of 24 h). As expected, social behaviour at 17 weeks was greater (P<0.01) for entire males and immuno-castrated than surgical-castrated males (3.8, 1.8 and 0.1% of 24 h), but not at 21 weeks, when it was greater (P<0.01) for entire males than immuno- and surgical-castrated males (1.8, 0.5 and 0.4% of 24 h). While the mean time pigs spent in the feeders at 17 weeks did not differ among the treatments (100 min/pig/24 h), at 21 weeks entire males spent less time (P<0.05) in the feeders (76 min/pig/24 h) than immuno- and surgical-castrated males (110 and 107 min, respectively). On both the observation occasions, the “sexually-active” treatments (entire males and immuno-castrated males at 17 weeks and entire males at 21 weeks of age) on average allocated about one-third of active time to feeding, whereas castrated males spent almost one-half of active time in the feeder, assumed to represent feeding behaviour (P<0.05). At 23 weeks, there was a trend for entire males to be lighter (P=0.061) than immuno-castrated males, with surgical-castrated males in between (102.3, 108.9 and 103.9 kg). Thus, castration reduced social behaviour and increased feeding behaviour in group-housed finisher pigs. The results of the experiment also suggest that the social and feeding behaviours of immuno-castrated males at 21 weeks were similar to surgically-castrated males. [Copyright &y& Elsevier]

Presents a study which assessed the efficacy of a gonadotrophin-releasing hormone (GnRH) vaccine in eliminating boar taint and increasing growth performance of boars. Chemical analysis of the testosterone concentration in serum of boars; Procedures in measuring antibodies to GnRH; Discussion.

This study validated the effect of gender (female, immunocastrated male; n = 50), electrical stimulation (none or 150 mA constant current for 30 s at 2 min post-slaughter) and ageing period (2 or 14 d) on the eating quality of pork roast and stir fry sourced from the loin ( M. longissimus thoracis et lumborum ) and silverside ( M. biceps femoris ) and steak from the loin only. Moisture infusion was applied to 2 d aged, non-stimulated primals as a positive control treatment. Neither gender nor ageing period influenced (P > 0.05) eating quality. Electrical stimulation and moisture infusion were each effective interventions in improving pork eating quality, but their effects were inconsistent between the five cuts evaluated. No interventions achieved the fail rate target of <10% for quality grade for all cuts, indicating that additional interventions are needed to enable industry to consistently deliver high quality pork. [ABSTRACT FROM AUTHOR]

Eating quality attributes of pork loin ( M. longissimus thoracis et lumborum ) and silverside ( M. biceps femoris ) from female and immunocastrated male carcases hung from either the Achilles tendon or aitchbone, aged for either 2 or 7 days post-slaughter and cooked as roasts, stir fry and steak (loin only) (n = 25/gender) was assessed. A positive control treatment of moisture infusion (10% injection rate) was applied to Achilles hung sides with cuts aged for 2 d post-slaughter. Neither gender nor ageing period influenced consumer sensory scores. Beneficial effects of aitchbone hanging on eating quality compared with Achilles hanging were largely observed after 2 d ageing, with improvements (P < 0.05) in overall liking scores found for loin stir fry and silverside stir fry and roasts. Overall liking scores of all cuts, except silverside stir fry, were increased (P < 0.05) when moisture infused compared with those from aitchbone-hung sides. However, targeted fail rates of <10% were not consistently achieved across all cuts evaluated. [ABSTRACT FROM AUTHOR]

Residual feed intake (RFI) is defined as the difference between the actual and expected feed intake required to support animal maintenance and growth. Thus, a cow with a low RFI can obtain nutrients for maintenance and growth from a reduced amount of feed compared with a cow with a high RFI. Variation in RFI is underpinned by a combination of factors, including genetics, metabolism, thermoregulation and body composition; hypothalamic-pituitary-adrenal (HPA) axis responsiveness is also a possible contributor. Responses to 3 metabolic challenges were measured in lactating and nonlactating dairy cattle. Sixteen Holstein Friesian cows with phenotypic RFI measurements that were obtained during the growth period (188–220 d old) were grouped as either low-calfhood RFI (n = 8) or high-calfhood RFI (n = 8). An ACTH (2 µg/kg of body weight), insulin (0.12 U/kg), and epinephrine (a low dose of 0.1 µg/kg and a high dose of 1.6 µg/kg of epinephrine) challenge were each conducted during both midlactation (122 ± 23.4 d in milk) and the nonlactating period (dry period; approximately 38 d after cessation of milking). Cows were housed in metabolism stalls for the challenges and were fed a diet of alfalfa cubes ad libitum for at least 10 d before the experiment (lactating cows also were offered a total of 6 kg of dry matter/d of crushed wheat grain plus minerals fed as 3 kg of dry matter at each milking) and were fasted for 12 h before the challenges. The efficiency of conversion of feed into milk (the ratio of feed consumed to milk produced over the 7 d before the experiment) during midlactation was better (lower) in low-calfhood RFI cows, although dry matter intake did not differ between RFI groups. Low-calfhood RFI cows exhibited a lower plasma cortisol response to the ACTH challenge than high-calfhood RFI cows, particularly in midlactation (−15%). The low-calfhood RFI cows had a greater plasma insulin-like growth factor-1 response to the insulin challenge and plasma fatty acid response to epinephrine compared with the high-calfhood RFI cows. These data suggest that high-calfhood RFI cows exhibit a more responsive HPA axis. As divergence in RFI measured during growth is retained (although reduced) during lactation, it is possible that energy is used to respond to HPA axis activation at the expense of production in high-calfhood RFI dairy cattle during lactation and contributes to a decrease in overall feed use efficiency. [ABSTRACT FROM AUTHOR]

This study investigated the effects of ageing period (2 or 7 days), endpoint temperature (70 or 75 °C), cut type (loin ( M. longissimus thoracis et lumborum), silverside (M. biceps femoris), blade (M. triceps brachii) and chuck tender (M. supraspinatus)), cooking method (roast and stir fry (all cuts) and steak (loin only)) on eating quality attributes of pork from entire and immunocastrated male pigs. Higher intramuscular fat levels were found in all cuts from immunocastrated males compared with entire males. Of the seven cut type × cooking method combinations evaluated, shoulder cuts had the lowest fail rate (P < 0.001) and loin steak and silverside cuts scored lowest (P < 0.001) for tenderness, juiciness, overall liking, quality grade and re-purchase intention. Although no differences in sensory scores due to gender were observed, boar taint was identified in 10% of entire males. Minimising adverse risks in eating quality due to boar taint in males remains a key industry issue to ensure consistent delivery of high quality pork. [ABSTRACT FROM AUTHOR]

Female crossbred pigs were randomly allocated at 16 weeks of age to one of three dietary treatments (A: corn and soybean meal; B: wheat and canola meal; C: wheat and sorghum) matched for digestible energy (13.6 MJ DE/kg) and total lysine (0.93–0.95%) and fed for 4, 5 or 8 weeks, respectively, prior to slaughter. Loin ( M. longissimus thoracis et lumborum ) and silverside ( M. biceps femoris ) were obtained from 20 pigs per dietary treatment group and prepared into steaks and roasts, respectively, for consumer evaluation with ageing treatments of 7 and 28 days post-slaughter allocated within muscle. Neither dietary treatment/age at slaughter nor ageing treatment influenced sensory traits of either cut. Intramuscular fat levels were also not influenced by dietary treatment. Higher (P < 0.001) fail rates for silverside roasts compared with loin steaks indicate that different interventions are needed at a cut level to optimise pork eating quality consistency and consumer expectations. [ABSTRACT FROM AUTHOR]

Consumers are the final step in the meat supply chain and meeting consumer expectations of quality and tenderness are important for satisfaction and repeat purchase. High pressure processing, shockwaves, ultrasound, pulsed electric field and muscle stretching can be applied to pre- and post-rigor meat for tenderisation. These non-thermal and thermal innovative technologies can be used with varying levels of success to cause physical disruption to muscle structure, enhanced proteolysis and ageing and muscle protein denaturation and solubilisation resulting in changes to texture and juiciness. Results of a meta-analysis are used to compare the effects of these technologies on meat tenderisation. In the future, a combination of new and innovative technologies will be ideally suited to deliver a range of desired textures for meat products. [ABSTRACT FROM AUTHOR]

Presents abstracts of articles on the topic of livestock nutrition in the field of clinical nutrition. 'Nutritional manipulation increases intramuscular fat in finisher gilts'; 'Housing temperature affects growth performance and carcass quality of pigs'; 'The effects of stress on feed intake, growth and plasma insulin like growth factor I (IGF-I) in growing pigs'; 'Supplementation of weaner diets with high levels of zinc.'

The objective of this experiment was to compare the pork quality of entire male pigs and pigs immunized against GnRF (IC males) at both light (64.8 kg) and heavy (106 kg) liveweights and two feeding regimes (restricted at 2.5 times maintenance and ad libitum ). There was no difference in objective measurements (P > 0.05) or eating pork quality (P > 0.1) between entire male and IC males. Fail rates were reduced by 9.1% and 12% for pork from IC males for quality grade (P = 0.007) and re-purchase intention (P = 0.001), respectively, compared to pork from entire males. Skatole (P = 0.001) and androstenone (P < 0.001) levels in belly fat were higher in entire male than IC male pigs. In addition, 37.5% of the light entire male pigs fed ad libitum showed skatole levels that exceeded the sensory threshold of 0.2 μg/g. This work confirms that immunization against GnRF is effective in eliminating boar taint and reducing pork quality fail rates by approximately 10% compared to pork from entire males. [ABSTRACT FROM AUTHOR]

The effect of gender (entire male, female and castrate), ageing period (2 or 7 days) and endpoint temperature (70 or 75 °C) on consumer perceptions of cuts from the loin ( Musculus longissimus thoracis et lumborum ), silverside ( Musculus biceps femoris ) and shoulder ( Musculus triceps brachii (roast) and Musculus supraspinatus (stir fry)) when roasted or stir fried (all primals) or grilled as steaks (loin only) was investigated. Higher scores for juiciness ( P = 0.035), flavour ( P = 0.017), overall liking ( P = 0.018), quality grade ( P = 0.026) were obtained from castrates than entire males, with females intermediate. Neither ageing period nor endpoint temperature, as main effects, influenced sensory scores. Loin steaks and silverside roasts obtained lower ( P < 0.001) scores for all sensory traits except aroma; scores for shoulder cuts were highest ( P < 0.001). Cooking to 70 °C improved ( P < 0.05) juiciness, flavor and overall liking scores of loin steaks compared with 75 °C. Different pathway interventions are required to optimize eating quality of different pork cuts and the cooking methods used to prepare them. [ABSTRACT FROM AUTHOR]

As nitric oxide (NO) is postulated to be a mediator of the effects of pre-slaughter stress on meat quality the aims of this experiment were to investigate the effects of modulating NO pharmacologically on meat quality of sedentary lambs. As pharmacological NO donors are prohibitively expensive to use in the lamb model l -Arginine, the substrate for NO synthase (NOS) was infused into lambs and increased NO production by ~ 30%. In a 2 × 2 factorial design we infused either l -Arginine (500 mg/kg) or the NOS inhibitor L-N G nitroarginine methyl ester hydrochloride (L-NAME, 30 mg/kg) 190 min pre-slaughter and investigated meat quality in the Longissimus thoracis lumborum (LTL) or Semimembranosus (SM). The principal outcome of the experiment was that L-NAME inhibited proteolysis and reduced tenderness in the SM. These data indicate that events pre-slaughter that affect NO synthesis can influence meat tenderness, potentially via altered muscle metabolism or modulation of proteolytic enzymes. [ABSTRACT FROM AUTHOR]

Abstract: Short day length (i.e. winter) is associated with reduced milk yield from dairy animals. Dairy cows and sheep have been successfully housed under lights throughout winter to extend the day length and increase milk yield, very little data exists on the effect of extended day length on the milk yield of dairy goats. The current study was conducted over an eight week period from June to August, 2009. A total of 542 Saanan and Saanan British Alpine cross goats were used, all producing ≥1.5L of milk per day, 253 in early lactation (5–20 days in milk) and 289 in late lactation (190–210 days in milk). Does were randomly allocated to either the control or the long day photoperiod (LDPP) groups, both were housed in open sided sheds with the LDPP group exposed to 16h of light, while the other received a natural lighting regime. Milking was conducted by machine and yield was automatically recorded daily. Doe weights were measured at the beginning of the study and subsequently at four-week intervals. Milk and blood samples were collected from a subset (n =30 and n =18 respectively) of animals in each of the four groups, at day 0 and then every four weeks. Milk was analysed for protein, lactose, bulk milk cell count (SCC), fat and solids-not-fat. Blood plasma was assayed for glucose, non-esterified fatty acids (NEFA) and prolactin. Treatment with LDPP significantly increased (P <0.001) milk yield, with the greatest response occurring in late lactation animals, who were producing 20% more milk than their control counterparts (+0.28kg/d). An increase in milk yield was evident by week 1 in late lactation and week 4 in early lactation. Overall, goats exposed to LDPP showed a decrease in milk fat % (P =0.003), milk protein % (P <0.001), milk solids not fat (P <0.001) and somatic cell count (P =0.012), but a slightly higher milk lactose % (P =0.010), when compared to control animals. LDPP increased milk protein (P =0.010), lactose (P =0.032) and SNF yield (P =0.034) in late lactation animals with the response being greater after 8 weeks than after 4 weeks of treatment. Plasma prolactin (P =0.007) and glucose increased with exposure to LDPP while the same animals showed a decrease in plasma NEFA. Liveweight increased (P <0.001) with LDPP exposure, was greater (P <0.001) in late lactation than in early lactation and increased (P <0.001) with week of treatment. Exposure to LDPP significantly increased milk yield and lactation persistence in Australian dairy goats, most substantially in late lactation. [Copyright &y& Elsevier]

Abstract: There is evidence that an atypical adrenoreceptor subtype is involved in mediating some of the physiological effects of catecholamines, particularly in some adipose tissue sites. Therefore, a study was conducted to determine the effect of the β3-agonist BRL35135A on growth performance and body composition in ruminant lambs. Twenty-two second cross wether lambs (32.5±0.7kg) were individually-housed in pens and randomly allocated on the basis of stratified live weights to two treatments (n =11 per treatment). The control group were offered barley (20%) and lucerne chaff (80%) ad libitum and the treated group were given the BRL35135A (1mg/30kg live weight) with the feed. Feed refusals were recorded daily and lambs weighed weekly. After 42days all lambs were slaughtered commercially and carcass, visceral organ and fat depots recorded. Chilled carcasses were scanned by dual-energy X-ray absorptiometry to measure body composition. Dietary β3-agonist treatment had no effect on average daily gain, final live weight or carcass weight but reduced residual feed intake (0.41 vs −0.41, P =0.061). There were no effects of dietary β3-agonist treatment on carcass chemical composition but β3-agonist treatment increased the weight of the feet (0.89 vs 0.94kg, P <0.05) and the skin (4.22 vs 4.56kg, P <0.05). Dietary β3-agonist treatment decreased the weight of the omental (0.64 vs 0.51kg, P <0.05) and perirenal (0.30 vs 0.23kg, P <0.05) fat depots. In conclusion, these data confirm that BRL35135A was active in sheep when given with feed, as indicated by a partitioning of nutrients from visceral fat mass and an improvement in feed efficiency. The effects on adipose tissue were specific to omental and perirenal fat as there was no change in carcass fat and these data are consistent with β3-receptors being the predominant β-receptor subtype in internal fat tissues. [Copyright &y& Elsevier]

Abstract: The present study investigated the effects of breed and diet quality on basal and hormone-stimulated energy metabolism in lambs. Twenty-four 7-mo-old merino (MM; n = 12) and second-cross (2X; n = 12) lambs were maintained indoors and fed ad libitum either a low-quality (7.8% crude protein [CP] and 8.1 MJ metabolizable energy [ME]/kg dry matter [DM]) or a moderate-quality (17.6% CP and 9.1 MJ ME/kg DM) diet in a crossover design. After 3 wk of feeding, lambs were injected intravenously with insulin (10 μg/kg body weight [BW]) and epinephrine (0.8 μg/kg BW) on consecutive days and blood samples were collected at −30, −15, −1, 3, 6, 10, 15, 20, 30, 45, 60, 90, and 120 min relative to time of injection. Lambs fed the low-quality diet had lower DM (P < 0.001), CP (P < 0.01), and ME (P < 0.001) intakes than lambs fed the moderate-quality diet. Baseline nonesterified fatty acid (NEFA) concentrations were higher (P < 0.001) in lambs fed a low-quality diet than in those fed a moderate-quality diet but there were no breed differences. Second-cross lambs had higher basal plasma concentrations of glucose (P < 0.001), lactate (P < 0.001), and cortisol (P < 0.02) than the MM lambs, although there was no effect of diet on any of these plasma variables. Insulin injection caused a rapid hypoglycemic response in all lambs but the response was more pronounced (P < 0.01) in MM lambs compared with 2X lambs. The cortisol response to insulin was twice as great (P < 0.05) in MM lambs compared with 2X lambs. There was a rebound in plasma NEFA concentrations after approximately 30 min postinjection that was most pronounced (P < 0.01) in MM lambs. Epinephrine injection caused a rapid increase in plasma NEFA, which tended to be lower in lambs fed the moderate-quality diet (P = 0.07) than in those fed the low-quality diet, but did not differ between breeds. Epinephrine injection caused rapid hyperglycemia, with the response being lower (P < 0.006) in lambs fed the moderate-quality diet compared with those fed the low-quality diet and greater (P < 0.050) in 2X than in MM lambs. Epinephrine injection caused a rapid increase in plasma lactate that tended to be greater (P = 0.07) in 2X lambs compared with MM lambs. The present study demonstrated clear breed differences in basal and hormone-stimulated metabolism, such that the 2X lambs appeared to be less sensitive to insulin and more sensitive to epinephrine than the MM lambs. These metabolic differences may be related to the fundamental differences in physiology that are associated with meat and wool production from 2X and MM breeds, respectively. They may also be related to adaptation of the MM breed to harsh environments through the ability of the body to metabolize fat resources, which are an efficient source of energy for survival. [Copyright &y& Elsevier]

Abstract: An Hologic QDR4500A dual energy X-ray absorptiometer (DXA) was used to measure live body composition in 15 second-cross wether lambs ((Border Leicester×Merino)×Poll Dorset) aged 6–8 months (17–50kg) and 13 mature ewes (composite terminal sire line based largely on Poll Dorset, White Suffolk and Texel breeds) (44–71kg). After slaughter, DXA scans were also performed on the whole carcasses. Values determined by DXA including total tissue mass (TTM), lean tissue mass (LTM), fat tissue mass (FTM) and bone mineral content (BMC) for the half carcass were evaluated by comparison with chemically determined composition. In the case of BMC the relationship was with chemically determined ash content. Live weight and chemically determined lean, fat and ash were strongly related to DXA-derived values for whole body TTM, LTM, FTM and BMC, respectively (R 2 =0.999, 0.988, 0.980 and 0.977, respectively). Carcass weight and chemically determined lean, fat and ash were strongly related to DXA-derived values for carcass TTM, LTM, FTM and BMC, respectively (R 2 =0.998, 0.984, 0.986 and 0.906, respectively). However, because DXA estimates were different from chemically determined values in this sample of carcasses, they needed to be adjusted with the use of appropriate regression equations to correct the in-built algorithms used to predict human body composition. These data demonstrate the efficacy of DXA as a non-destructive method for determining the composition of the whole body and carcasses of sheep. [Copyright &y& Elsevier]

Abstract: Metabolic rate and energy consumption increase through the activation of the hypothalamic-pituitary-adrenal axis when an animal is exposed to a stressor. Residual feed intake (RFI) as a measure of efficiency has been shown to be related to exogenous adrenocorticotropin hormone (ACTH)-stimulated cortisol concentrations, which is indicative of the relationship between an animal''s response to stress and the efficiency with which the energy is used for growth and production. In this study, we tested the hypothesis that sheep with low post-ACTH serum cortisol concentration relative to the other sheep in the flock have lower RFI values and lower cortisol concentrations following insulin-induced hypoglycemia. Adrenocorticotropin hormone (2.0 μg/kg body weight)-stimulated cortisol concentrations were measured in 100 sheep. The extreme responders were selected (n = 12 high cortisol, n = 12 low cortisol), and feed efficiency and body composition parameters were measured. A second ACTH challenge and an insulin challenge were administered. More efficient sheep (more negative RFI value) were found to have lower (P < 0.05) cortisol concentrations following both an ACTH challenge and an insulin challenge. Low-cortisol sheep (low response to ACTH or insulin) were found to have a lower (P < 0.05) proportion of fat tissue in comparison to the high-cortisol animals. These data clearly indicate that an animal''s response to exogenous ACTH or insulin-induced hypoglycemia as a stressor is related (P < 0.05) to efficiency of energy use when measured as RFI. These data have important implications in enabling identification of animals that are superior in terms of feed efficiency and for understanding the physiological mechanisms underlying efficiency of energy use. [Copyright &y& Elsevier]

Abstract: Chronic elevation of glucocorticoid concentrations is detrimental to health. We investigated effects of chronic increase in plasma cortisol concentrations on energy balance and endocrine function in sheep. Because food intake and reproduction are regulated by photoperiod, we performed experiments in January (JAN) and August (AUG), when appetite drive is either high or low, respectively. Ovariectomized ewes were treated (intramuscularly) daily with 0.5mg Synacthen Depot® (synthetic adrenocorticotropin: ACTH) or saline for 4 wk. Blood samples were taken to measure plasma concentrations of cortisol, luteinising hormone (LH), follicle-stimulating hormone (FSH), growth hormone (GH), leptin, insulin, and glucose. Adrenocorticotropin treatment increased concentrations of cortisol. During JAN, treatment reduced food intake transiently, but increased food intake in AUG. Leptin concentrations were reduced and glucose concentrations were greater in AUG, and insulin concentrations were similar throughout the year. Treatment with ACTH increased leptin concentrations in AUG only, whereas insulin concentrations increased in JAN only. Synacthen treatment increased glucose concentrations, with a greater effect in JAN. Changes in truncal adiposity and ACTH-induced cortisol secretion were positively correlated in JAN and negatively correlated in AUG. Treatment reduced the plasma LH pulse frequency in JAN and AUG, with an effect on pulse amplitude in JAN only. Treatment did not affect plasma GH or FSH concentrations. We conclude that chronically elevated cortisol concentrations can affect food intake, adiposity, and reproductive function. In sheep, effects of chronically elevated cortisol concentrations on energy balance and metabolism depend upon metabolic setpoint, determined by circannual rhythms. [Copyright &y& Elsevier]

Abstract: The aim of this experiment was to determine the effect of inhibiting the release of nitric oxide (NO) pre-slaughter in lambs on post-slaughter muscle metabolism and meat quality. Exercise was used as a positive control as NO is known to be released in skeletal muscle during exercise. Forty Border Leicester×Merino lambs were assigned to the treatments L-NAME (NO synthase inhibitor) infusion (0mg/kg vs. 30mg/kg, 135min pre-slaughter) and exercise (none vs. 15min immediately pre-slaughter). The inhibition of NO release using L-NAME reduced Warner–Bratzler shear force (WBSF) in the longissimus thoracis et lumborum (LTL) after 3days of ageing, while the Semimembranosous (SM) was unaffected. Inhibition of NO release with L-NAME resulted in altered glucose metabolism as indicated by reduced plasma glucose pre-slaughter particularly in exercised lambs, reduced LTL and SM glycogen of non-exercised lambs post-slaughter and increased SM lactate in exercised lambs post-slaughter. In conclusion, inhibition of NO Synthase with L-NAME pre-slaughter increases post-mortem glycolysis and improves tenderness in the loin muscle. [Copyright &y& Elsevier]

Abstract: The concept of residual feed intake (RFI), in determining differences among animals in converting feed into body tissue, was first raised in 1963. Feed efficiency is typically calculated as a function of liveweight gain (LWG) and feed intake (FI). Historically two versions of the same model were proposed, one where FI was adjusted for liveweight (LW) and LWG, and the other where LWG was adjusted for FI and LW. Variation in LWG or FI could then be partitioned into two parts; that which is expected and can be attributed to differences in FI or LWG; and that which is the residual portion, which is the deviation from the expected value based on regression, and therefore not accounted for by differences in FI or LWG. Based on this definition, it is the residual portion which is the measure of efficiency. Both within a livestock industry and between different livestock industries there is no set model for calculating RFI. This paper evaluated four models used to calculate RFI and one model used to calculate residual LWG (RLWG) at a standard level of nutrition. They were the main model currently in use in the Australian beef cattle industry (RFIB), the original models proposed in 1963 (RFI1963; RLWG1963); a French model which included ultrasound measures of muscle and fat depth (RFIF) and the use of the Australian feeding standards to calculate predicted intake and thus RFI (RFISCA). Using feed intake, liveweight and body composition data generated from the same group of sheep (n =52) at two ages (6mo, 13mo), the relative merits of each model were evaluated and compared to the other models, to determine the most appropriate model to calculate RFI for sheep. For all the models except that used to calculate RLWG, over half of the variation in FI could be explained by the model. The amount of variation in FI accounted for depended on the parameters included and the dataset, with less variation in FI explained by the specific models in the older animals. The RFIF model, which included measures of body composition, accounted for the greatest proportion of the variation in FI and as such suggests that the inclusion of body composition parameters is likely to more accurately reflect true biological efficiency. [Copyright &y& Elsevier]

Abstract: An animal''s response to a stressor is to increase metabolic rate, and thus energy consumption through the activation of the hypothalamic–pituitary–adrenal axis. Changes to energy use by an animal are likely to influence the efficiency with which it is utilised. In this study, we tested the hypothesis that less efficient sheep are more responsive to exogenous administration of adrenocorticotropin hormone. This was done by firstly determining the appropriate dose (0.4, 1.6 or 6.4μg/kg LW) and peak serum cortisol response time (45min) to exogenous administration of adrenocorticotropin hormone in a pilot study (n =3 sheep). Following this, adrenocorticotropin hormone (2.0μg/kg LW) stimulated cortisol levels were measured in a larger group of sheep (n =50) of known feed efficiency (feed conversion ratio and residual feed intake values). Less efficient sheep (more positive residual feed intake values) were found to have a greater (P <0.001) increase in cortisol concentration in comparison to more efficient animals. Those sheep which had higher levels of cortisol also had a greater proportion (P <0.001) of fat tissue. These data clearly demonstrated that efficiency of energy use, when measured as residual feed intake, is significantly related to an animal''s stress response. These findings have important implications for understanding the physiological mechanisms underpinning efficiency of energy use, and may be useful in successfully identifying animals which are superior in terms of feed efficiency. [Copyright &y& Elsevier]

Eighty Large White×Landrace×Duroc crossbred female pigs of similar age were used in this experiment to investigate the deposition of fat and lean muscle tissue in the different primal cuts and intramuscular (IM) fat levels (longissimus dorsi, biceps femoris and supraspinatis) in female finisher pigs from 16 to 25 weeks of age. The pigs were group housed (10 pigs/pen) and randomly allocated to 1 of 10 pens. The pigs in each pen were allocated a slaughter age over a 10-week period starting from Week 16 to Week 25. The liveweight, carcass weight, and backfat depth at the P2 site significantly increased (P<0.001) from 16 to 25 weeks of age. The weight of the carcass and primal cuts, and the fat and lean muscle content of the half carcass and the shoulder, loin, belly and ham primal cuts increased significantly (P<0.001) from 16 to 25 weeks of age. There was no significant difference (P>0.05) in IM fat levels in the loin (m. longissimus) and the shoulder (m. suprasinatis) muscle. The IM fat levels varied significantly (P=0.003) in the ham (m. biceps femoris) muscle with the highest IM fat levels in pigs of 21 weeks of age and lowest in pigs at 17 weeks of age. The results indicate that the fat to lean muscle ratio increased significantly for the carcass (P=0.004), shoulder (P<0.001), loin (P=0.001), belly (P<0.001) and the ham (P=0.026) primal cuts from 16 to 25 weeks of age. Animal age was significantly correlated (P<0.001) with the fat content of the carcass and primal cuts. The strongest correlation between age and fat content was for the belly primal cut (r2=0.603). [Copyright &y& Elsevier]

• IRT and machine learning techniques provide new opportunities to non-invasively measure heat stress in sheep. • IRT temperatures of forehead, eye and nostril regions were highly correlated with THI and rectal temperature. • Artificial neural network model developed applying Bayesian regularization algorithm showed highest accuracy and performance for predicting rectal temperature using IRT. Heat stress (HS) leads to altered sheep behavior, physiological, and biochemical processes which negatively affects their welfare and performance. While suitable strategies are needed to ameliorate the impacts of HS in sheep, it is equally important to accurately and non-invasively measure HS. Traditionally, rectal temperature (RT) is considered an indicator of thermal balance and is used to assess the impacts of hot conditions on sheep. However, measuring RT itself can be a stressor as it often requires restraining of the animals. The main objective of this study was to establish whether a combination of infrared thermography (IRT) and machine learning techniques can be applied to predict sheep RT when subjected to HS. Thermal images and RT were taken twice weekly from Dorper, and 2nd Cross (Poll Dorset X (Border Leicester X Merino)) lambs (n = 24/breed, 4−5 months old), for two weeks. Sheep were randomly allocated to either (i) thermoneutral (TN; 18–21 °C, 30–50 % relative humidity (RH), n = 12/group) or (ii) cyclic HS treatments (28–40 °C, 40–60 % RH, the cycle comprised of high temperatures 38−40 °C between 0800 and 1700 h daily and 28 °C, 30–40 % RH maintained overnight). The head was selected as the region of interest because of less wool cover; specifically, the IRT of forehead, eye, ear, nostril, and face locations were measured. Artificial neural network (ANN) models were developed using three different backpropagation algorithms with temperature-humidity index (THI), and IRT temperatures as inputs and RT measured manually as targets. Results showed that the forehead and eye IRT temperatures had the highest correlation (P < 0.01) with THI and RT. Further, Bayesian Regularization, with one hidden layer containing 10 neurons with a tangent sigmoid transfer function, showed the best correlation (R = 0.92) and highest performance (MSE = 0.02). The model developed may be a rapid and cost-effective technique to monitor real-time body temperatures in sheep and also to detect HS with minimal restraint. [ABSTRACT FROM AUTHOR]

Responses of dairy cows with high or low milk yield (MY) beyond 450 d in milk (DIM) to 3 metabolic challenges were investigated. Twelve multiparous Holstein-Friesian cows that calved in late winter in a pasture-based system were managed for a 670-d lactation by delaying re-breeding. Cows were selected for either high MY (18.9 ± 1.69 L/cow per d; n = 6) or low MY (12.3 ± 3.85 L/cow per d; n = 6) at 450 DIM. Cows were housed indoors for 2 periods of 12 d at approximately 460 and 580 DIM. Each cow was fed freshly cut pasture (460 DIM) or pasture silage (580 DIM) plus 6.0 kg of DM barley grain daily (approximately 200 MJ of total metabolizable energy/cow per day). At all other times, cows were managed as a single herd and grazed pasture supplemented with cereal grain to an estimated intake of 180 MJ of metabolizable energy/cow per d. Cows were fitted with a jugular catheter during the final week of each experimental period. Over a period of 3 d, each cow underwent an intravenous glucose tolerance test (0.3 g/kg of body weight), an insulin tolerance test (0.12 IU of insulin/kg of body weight), and a 2-dose epinephrine challenge (0.1 and 1.6 µg/kg of body weight). Cows selected for high MY had greater milk and milk solids yields between 450 and 580 DIM than low MY cows (17.3 vs. 10.8 ± 1.49 kg of milk/d and 2.4 vs. 1.5 ± 0.23 kg of milk solids/d). The results indicated that whole body and peripheral tissue responsiveness to insulin may vary between cows of high and low MY. Following the glucose tolerance test, high MY cows had a lower plasma insulin response with a greater glucose area under the curve than low MY cows. Further, high MY cows had slower plasma glucose clearance compared with low MY cows during an insulin tolerance test. The plasma nonesterified fatty acid (NEFA) responses to the IVGTT and the ITT were similar between cows of high and low MY, but the clearance of NEFA from the plasma following both the IVGTT and ITT were slower at 580 compared with 460 DIM. The sensitivity to epinephrine was greater in high MY cows compared with low MY cows as the glucose and NEFA area under the curve and the percentage change in NEFA were greater in high MY after the low dose epinephrine challenge. However, the lipolytic but not the glucose appearance in response to epinephrine was greater in high MY cows than low MY cows. Following the high dose of epinephrine, the glucose response was lower, but the NEFA response was greater in high MY compared with low MY cows. Cows able to sustain greater MY to 580 DIM had a greater propensity for lipid mobilization, possibly enhancing nutrient partitioning to the mammary gland during the late stages of an extended lactation. [ABSTRACT FROM AUTHOR]

Abstract This study investigated the use of camelina forage and meal supplementation to a finishing diet on carcass traits, composition and retail value of lamb and hoggets. The metabolisable energy and crude protein concentrations of all 3 diets were 10–11 MJ/kg DM and 14–15% CP. Thirty maternal Composite wether lambs (28–38 kg) and 30 Merino wether hoggets (37–43 kg) were used in a 3 × 2 factorial experiment. Animals were slaughtered after 10 weeks of feeding with carcasses classified as 'Heavy lamb' or 'Heavy hogget' (>22 kg carcass weight). Carcass traits, composition, meat mineral concentrations and retail colour were measured. Camelina diets increased liveweight (P < 0.02) and carcass weight (P < 0.002) for both sheep types. Carcass weight (P < 0.005) and dressing % (P < 0.01) were lower for Merino hoggets than Composite lambs. Mineral concentration and retail colour stability of fresh meat were unaffected by diet, with 72 h retail colour considered acceptable for consumers. [ABSTRACT FROM AUTHOR]

Abstract Dietary supplementation of vitamin E (VitE) in a synthetic or natural form was examined. Forty-eight lambs were assigned (n = 16) to either a grain-based diet at moderate (MOD, 42 mg∙kg−1 VitE as all-rac α-tocopheryl acetate) or supranutritional (SUP, 285 mg∙kg−1 of vitE) levels of synthetic VitE or a lucerne hay-based diet (LUC; 37 mg∙kg−1 VitE) for 8 weeks. Meat from the LUC group had lower muscle n-6 and PUFA levels compared to meat from the MOD and SUP groups. Despite a similar VitE intake, muscle VitE was higher for LUC compared to MOD, while SUP lambs showed the highest VitE. Lipid oxidation did not differ between groups. For fresh meat, redness tended to be higher in LUC fed lambs than the other two groups, but brownness formation was only lower than the SUP group. For aged meat colour stability, redness tended to be higher in lambs fed SUP and LUC, whereas highest browning occurred in the MOD group. [ABSTRACT FROM AUTHOR]

Highlights • The n-alkane technique provided good estimates of herbage intake of individual dairy cows. • The accuracy of the technique was not affected by herbage mass or season. • The alkane pair C 33 /C 32 provided the most precise estimates of feed intake. Abstract The n-alkane technique for estimating herbage dry matter intake (DMI) of dairy cows was investigated in this experiment. Eight Holstein-Friesian dairy cows were offered perennial ryegrass ad libitum that had been harvested at two different herbage masses and during two different seasons, in order to assess the effect of herbage mass and season on the accuracy of the n-alkane technique. Two pre-harvested herbage mass treatments (low, target 1500 kg DM/ha versus high, target 4000 kg DM/ha, measured above 4 cm), were investigated in a crossover factorial arrangement within each of two seasons (summer versus autumn), in Ireland. Each season consisted of two periods, each 12 days in length. Cows were housed in individual metabolism stalls to allow for accurate determination of measured DMI. Herbage DMI was estimated, with the n-alkane technique, by dosing cows twice daily with a C 32 n-alkane. Pre-harvest herbage mass and season did not affect the n-alkane estimated DMI, although lack of season and herbage mass effects may have been masked by variation that occurred between swards within the same herbage mass and season. However, there were a number of differences between summer and autumn in the fecal recovery rates of a number of n-alkanes suggesting that the effect of season requires further investigation prior to the application of recovery rates from literature values when investigating diet selection and botanical composition. Overall, the n-alkane technique provided good estimates of DMI; the discrepancy had a standard deviation due to sward of 1.2 and 1.0 kg DM/cow per day, and hence potential bias of up to twice this, and a measurement error standard deviation of 1.3 and 1.0 kg DM/cow per day, for the C 33 /C 32 and C 31 /C 32 n-alkane pair methods respectively. Two n-alkane pairs were tested, and C 33 /C 32 n-alkane provided the most precise estimates of DMI, compared with the C 31 /C 32 n-alkane pair. This research provides some strong evidence for future use of the n-alkane technique including that the accuracy of the technique has not been influenced by contemporary changes to herbage management, is not affected by seasonal changes, and overall is an accurate and precise technique for estimating DMI. [ABSTRACT FROM AUTHOR]

The Australian pork industry is strongly committed to assuring the integrity of its product, with substantial research investment made over the past ten years to develop and implement systems to assure the consistency and quality of fresh pork and to enable accurate tracing of unpackaged fresh pork back to property of origin using trace elemental profiling. These initiatives are pivotal to allow Australian pork of guaranteed eating quality to be successfully positioned as higher value products, across a range of international and domestic markets, whilst managing any threats of product substitution. This paper describes the current status of the development of a predictive eating quality model for Australian pork, utilizing eating quality datasets generated from recent Australian studies. The implementation of trace elemental profiling, by Physi-Trace™, to verify and defend provenance claims and support the supply of consistently high eating quality Australian pork to its customers, is also discussed. [ABSTRACT FROM AUTHOR]

This experiment investigated the metabolic response to a 2-dose epinephrine challenge of dairy cows undergoing an extended lactation. Twelve multiparous Holstein-Friesian cows that calved in late winter in a seasonally calving pasture-based dairying system were managed for a 670-d lactation by delaying rebreeding. In each of four 40-d experimental periods commencing at 73, 217, 422, and 520 (±9.1) d in milk (DIM), cows were offered a diet of perennial ryegrass (73 and 422 DIM) or pasture hay and silage (217 and 520 DIM), supplemented with 1 (CON; n = 6) or 6 kg of grain (GRN; n = 6) as a ration. Daily energy intake was approximately 160 and 215 MJ of metabolizable energy/cow for the CON and GRN treatments, respectively. At all other times, cows were managed as a single herd and grazed pasture supplemented with grain to an estimated daily total intake of 180 MJ of metabolizable energy/cow. Cows were fitted with a jugular catheter during the final week of each experimental period. Two doses of epinephrine (0.1 and 1.6 µg/kg of body weight) were infused via the catheter 2 h apart to each cow at approximately 100, 250, 460, and 560 DIM. Blood plasma concentrations of glucose and nonesterified fatty acids (NEFA) were measured before and after infusions. Cows in the GRN treatment had greater milk yield, milk fat and protein yields, and body weight than cows in the CON treatment. The maximum plasma glucose concentration was observed at 100 DIM for both the low and high doses of epinephrine. Thus, sensitivity and responsiveness to exogenous epinephrine were greater during early lactation, coinciding with increased priority of milk synthesis. Both the sensitivity and responsiveness to epinephrine decreased with decreasing milk yield, as measured by the acute appearance of NEFA in the plasma. Increased plasma glucose and NEFA clearance rates before 300 DIM indicated greater uptake of these substrates by the mammary gland for milk synthesis in early and mid lactation. These results support previous findings that major changes occur in terms of adipose tissue metabolism during extended lactations. Overall, sensitivity to epinephrine was not affected by diet, but responsiveness was greater in cows fed the GRN diet. The endocrine regulation of nutrient partitioning throughout traditional and extended lactations is complex, with many interactions between stage of lactation, diet, and milk yield potential. [ABSTRACT FROM AUTHOR]

A small angle X-ray scattering (SAXS) synchrotron was used to evaluate 100 ovine m . longissimus lumborum , representing lamb (n = 50) and sheep (n = 50). The diffraction of X-rays gives information on muscle myofibril structure and fat content. The linear relationships between SAXS measures with measures such as, shear force, intramuscular fat content (IMF) and collagen content/solubility, were investigated. A relationship was found between the d-spacing of the actin/myosin fibril spacing (SAX1 and SAX2) and the cross sectional area of the rhombohedral unit cell (Cell area) and shear force after 1 and 5 day ageing. There was a positive relationship between IMF and a SAXS Fat area measure. There was a muscle site effect on SAX1, SAX2 and Cell area, with the cranial site having a larger distance between myofibrils. The potential of SAXS as a powerful research tool to determine not only the structural components of ovine tenderness, but also the fat content related to IMF is evident. [ABSTRACT FROM AUTHOR]

Monte Carlo simulation was investigated as a potential methodology to estimate sensory tenderness, flavour and juiciness scores of pork following the implementation of key pathway interventions known to influence eating quality. Correction factors were established using mean data from published studies investigating key production, processing and cooking parameters. Probability distributions of correction factors were developed for single pathway parameters only, due to lack of interaction data. Except for moisture infusion, ageing period, aitchbone hanging and cooking pork to an internal temperature of > 74 °C, only small shifts in the mean of the probability distributions of correction factors were observed for the majority of pathway parameters investigated in this study. Output distributions of sensory scores, generated from Monte Carlo simulations of input distributions of correction factors and for individual pigs, indicated that this methodology may be useful in estimating both the shift and variability in pork eating traits when different pathway interventions are applied. [ABSTRACT FROM AUTHOR]

The present study was conducted to elucidate the role of dietary vitamin E (Vit E) and selenium (Se) on the oxidative status of lambs exposed to short term hot conditions during finishing. Forty-eight lambs (crossbred; 42 ± 2 kg body weight, 7 mo age) were allocated to one of three groups (16 per group) and fed 3 different doses of Vit E and Se. A standard finisher pellet ration (17% CP and 12.57 MJ ME/kg DM) was used as the basis of treatment diets. The doses of Vit E and Se for control (CON), moderate (MOD), and supranutritional (SUP) diets were 28, 130, 228 mg/kg DM as α- tocopherol acetate and 0.16, 0.66, 1.16 mg Se as SelPlex™ kg/DM, respectively. After 4 weeks feeding in individual pens, including 1 week of adaptation, lambs were moved to metabolism cages for 1 week and allocated to one of 2 heat regimes (8 per feeding group): thermoneutral (TN) (18–21 °C and 40–50% relative humidity) or heat stress (HS) (28–40 °C and 30–40% relative humidity) conditions. Dietary Vit E and Se supplementation increased average daily feed intake ( P = 0.009) and average daily gain ( P = 0.057) linearly (CON to SUP) during the 3 week finisher period before thermal treatments were applied. During thermal treatment, HS elevated ( P < 0.001) both respiration rate (RR) and rectal temperature (RT). However, there were reductions in both RR ( P = 0.05) and RT ( P = 0.08) in lambs fed SUP levels of Vit E and Se. The concentration of plasma reactive oxygen metabolites (ROM) increased ( P < 0.001) under HS, but were reduced by the SUP diet (117CARR U) as compared to CON (128CARR U). The concentration of plasma advanced oxidation protein products (AOPP) were increased ( P < 0.001) during HS. Again, lambs fed the SUP diet had 35% lower (P = 0.005) AOPP levels than maximum levels in CON lambs when exposed to heat. Both RR and RT of lambs finished under HS were normalized after 14 h in lairage under TN conditions. Taken together, these data indicate that high levels (SUP) of dietary Vit E and Se improve average daily feed intake and average daily gain, and maintain oxidative balance in finisher lambs exposed to a heat stress challenge. [ABSTRACT FROM AUTHOR]

The introduction of East Friesian (EF) genetics into commercial sheep milking herds has the potential to improve milk yield and offer a robust dam for meat lamb production systems. This study was conducted to measure the milk production, feed intake and longitudinal changes in body composition of EF × Romney (EFR) and Border Leicester × Merino (BLM) ewes over the first nine weeks of lactation. Sixteen seconds parity single-bearing EFR ( n = 8) and BLM ( n = 8) ewes that had been mated to a purebred EF ram were housed in individual pens from 2 weeks prior to, and until 9 weeks after, lambing and fed a commercial pelleted diet with additional chaff. Milk yield was measured twice a week using the four-hour milking interval technique after injection of oxytocin and body composition was determined by dual energy X-ray absorptiometry (DXA) at 1, 3, 5 and 9 weeks of lactation. Potential milk production was higher in EFR than BLM ewes (2.57 vs. 1.92 kg/d, P = 0.028) and declined as lactation advanced. Similarly, the yields of milk fat ( P = 0.015), protein ( P = 0.018) and lactose ( P = 0.062) were all higher in EFR than BLM ewes and declined as lactation advanced. Energy intake increased over the first 4 weeks of the study, before reaching a plateau for the remaining 5 weeks of the study. However, there was no significant difference in energy intake or energy balance between EFR and BLM ewes. Changes in tissue energy between DXA scans were highly correlated ( R 2 = 0.51, P < 0.001) to average estimated energy balance over the same periods. There was no effect of breed on birth weight of lambs nor was there any effect of dam breed on average daily gain of lambs. In conclusion, EFR ewes have greater potential milk yield than BLM ewes but this was not realized as an increased average daily gain in the single lambs possibly due to insufficient milking pressure failing to produce a difference in actual milk yield. It is likely that this difference would be expressed in response to a greater milking demand (i.e. from a milking machine or twin/triplet lambs). The EFR ewes ate more than BLM ewes during lactation and mobilized less fat than BLM ewes to maintain similar nursing lamb growth. However, a greater milking demand of twins or triplets may allow the greater potential milk yield of EFR to be expressed. Alternatively, machine milking EFR would most likely allow the expression of their full milking potential. Finally, DXA was able to predict body tissue mobilization and accretion in lactating ewes and these changes in body composition were related to estimated energy balance indicating that DXA can be used to serially determine body composition in lactating sheep. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the influences of milk supplementation during lactation, over 1 wk after weaning, and oxytocin administration for the first 14 d of life on the pigs' response to weaning. Pigs from 20 litters were allocated to each of these 3 treatments in a randomized factorial design. Oxytocin was administered subcutaneously daily from 0 to 14 d of age at a rate of 10 I.U. per kg. The milk supplement consisted of a mixture of 25% skim milk powder offered either during lactation between 10 and 20 d of age or for the first week after weaning as a transitional diet along with dry pellets. Pigs were weaned at 21 d of age. Growth rate was measured from birth to slaughter at 140 d of age and feed intake of supplemental milk or feed from 10 to 56 d of age. Organ weights (heart, liver, stomach, and kidneys) and the gene expression of ghrelin, leptin, and glucagon-like peptides (glucagon-like peptide-1 and glucagon-like peptide-2) were measured in the stomach, ileum, and duodenum at 10, 21, and 28 d of age. Milk supplementation after weaning resulted in immediate feed intake and partially alleviated the depression in growth rate over the first 7 d postweaning ( P < 0.001), but milk supplementation during lactation had no effects ( P > 0.1). However, effects were only transient and disappeared once the milk liquid diet was removed. Neonatal oxytocin administration reduced weight loss over the first 2 d after weaning ( P = 0.03), without affecting feed intake ( P > 0.1), hence possibly reducing weaning stress. Seven days after weaning, oxytocin-treated pigs had greater stomach ghrelin and leptin expression (both P = 0.02), and pigs supplemented with milk after weaning had greater stomach leptin and glucagon-like peptide-2 expression ( P = 0.02 and P = 0.05, respectively). Hence, neonatal oxytocin administration or postweaning milk supplementation are both effective means of enhancing gastric leptin expression and reducing weight loss at weaning, likely improving gut health during this critical period. [ABSTRACT FROM AUTHOR]

Abstract: Fifty six Lori-Bakhtiari feedlot lambs (initial BW=44±4.7kg) were used in a 2×3+1 factorial experimental design to evaluate the effects of 3 feeding regimens of zilpaterol hydrochloride (ZH) for the last 28 and 42dbefore slaughter on growth performance, carcass characteristics and some plasma metabolites. The continuous feeding of ZH (daily regimen), intermittent 1d feeding ZH followed by 1d of withdrawal (1 on 1 off regimen), and intermittent 2d feeding ZH followed by 2d of withdrawal (2 on 2 off regimen) were employed as the different regimens. The lambs were assigned to one of seven treatments (8 lambs/treatment) based on initial BW. Lambs were fed a diet formulated to contain 14% CP and 2.45Mcal/kgDM of metabolizable energy (ME) supplemented with 0.2mg ZH/kg of live weight d−1. The basal diet without ZH was the added control group. Lambs fed ZH continuously for 28d had higher (P <0.001) feed efficiency compared to the control group and other intermittent regimens. Neither feeding regimen nor period had any significant effect (P >0.05) on final BW, total weight gain, average daily gain and dry mater intake. Hot and cold carcass weights and dressing percentage were greater for daily feeding for either 28 or 42d and for the 1 on 1 off-42d treatments than for the control and the other groups fed ZH (P <0.05). Longissimus dorsi muscle area was increased (P <0.01) by daily-28d compared to the control. Back fat thickness tended to be lower (P =0.063) in pooled ZH-treated groups whereas there was no effect of ZH on the proportion of final weight of the fat-tail. Daily-28d and 1 on 1 off-42d groups had lower intramuscular fat content (P <0.01) than the control group. Plasma concentrations of urea were decreased (P <0.05) in daily-28/42d groups compared to the control. Also, there were lower concentrations of urea after 42d of ZH feeding compared to 28d of ZH feeding (P <0. 05). Overall, feeding ZH in daily for either 28 or 42d before slaughter as well as for 42d on alternate days improved feed efficiency ratio and some carcass characteristics. While backfat tended to be decreased by ZH there was no effect on fat-tail in Lori-Bakhtiari lambs. [Copyright &y& Elsevier]

Abstract: The influence of dietary lecithin at doses of 0, 4, 20 or 80g/kg fed to finisher gilts for six weeks prior to slaughter on growth performance, carcass quality and pork quality was investigated. M. longissimus lumborum (loin) was removed from 36 pig carcasses at 24h post-mortem for Warner–Bratzler shear force, compression, collagen content and colour analyses. Dietary lecithin increased dressing percentage (P=0.009). Pork chewiness and collagen content were decreased by dietary lecithin (P<0.05, respectively), suggesting that improved chewiness may be due to decreased collagen content. However, dietary lecithin had no effect on shear force, cohesiveness or hardness (P>0.05, respectively). Dietary lecithin reduced loin muscle L* values and increased a* values (P<0.05, respectively) but no changes on b* values (P=0.56). The data showed that dietary lecithin improved dressing percentage and resulted in less chewy and less pale pork. [Copyright &y& Elsevier]

Abstract: A comparison has been made on the application of SPME and SDE for the extraction of volatile compounds from heated beef and sheep fats with separation and measurement by gas chromatography–mass spectrometry. As far as we know, this report represents the first time that such a comparison has been made for the measurement of volatile compounds in heated sheep fat. Approximately 100 compounds (in relatively high abundance) were characterised in the volatile profiles of heated beef and sheep fats using both techniques. Differences were observed in the volatile profiles obtained from each technique, independent of compound class. Rather than rate one technique as superior to another, the techniques can be regarded as complementary to each other. [Copyright &y& Elsevier]

Abstract: The characteristic mutton odour, associated with the cooked meat of older sheep, can be problematic for some consumers who find the odour disagreeable. Branch chain fatty acids (BCFAs) are considered to be the main determinants of mutton odour. In this study, the aim was to identify the factors influencing the BCFA content of animals at abattoirs in Australia. Samples of subcutaneous fat from over the chump (gluteus medius) were collected from 533 sheep carcasses at abattoirs in New South Wales, Victoria and Western Australia. The carcasses were from sheep differing in age, gender, breed and nutrition. The concentrations of three branched chain fatty acids (BCFAs); namely, 4-methyloctanoic (MOA), 4-ethyloctanoic (EOA) and 4-methylnonanoic acids (MNA), were determined. Statistical modelling showed that, with pre-slaughter nutrition in the model as a random term, BCFA concentrations could be used for discriminating the age of sheep. Fat samples from lamb carcasses had lower MOA and EOA concentrations and a higher concentration of MNA in comparison to hogget and mutton (P <0.05). When nutrition was excluded as a random effect from the statistical model, the MOA and MNA concentrations did not differentiate between lamb, hogget and mutton whereas, for EOA, lamb had a lower concentration than mutton (P <0.05) with hogget intermediate. An interaction existed between age and gender (P <0.05) where female lambs had lower EOA concentrations relative to the mutton but not for castrates. [Copyright &y& Elsevier]

Abstract: This study examined the level of long chain omega-3 and omega-6 polyunsaturated fats, the ratio of polyunsaturated fat to saturated fat (PUFA/SFA) and the ratio of omega-6 to omega-3 (n-6/n-3) fat in sheep grown under grazing conditions in Australia. The sheep genotypes used were Poll Dorsetgrowth ×Border Leicester Merino (PDg×BLM), Poll Dorsetgrowth ×Merino (PDg×M), Poll Dorsetmuscling ×Merino (PDm×M), Border Leicester×Merino (BL×M) and Merino×Merino (M×M). Loin muscles (Longissimus lumborum) collected from 40 ewe and wether sheep slaughtered at 14months of age were processed for fatty acid determination. After frozen storage, 20g samples were minced and a 7g homogenate was processed for muscle lipid extraction using a chloroform:methanol (2:1) procedure. There was an increase in PUFA/SFA as the proportion of Merino genetics increased in the progeny (second-cross

An Hologic QDR4500 dual energy X-ray absorptiometer (DXA) was used to measure body composition in 151 pigs ranging from 10 to 120 kg live weight. Large White×Landrace pigs of mixed sexes were selected from five different experiments to evaluate DXA accuracy within and across experiments. Values predicted by DXA including total tissue mass, fat tissue mass, lean tissue mass and bone mineral content, for the live animal, carcass and half carcass were evaluated by comparison with chemically-determined values. Relationships between chemically-determined values and measurements of weight and backfat at the P2 site were also evaluated. Chemically-determined values were strongly related with DXA-derived values, more so than with weight and P2 or a combination of both, particularly in the measurement of fat composition. In contrast to estimates derived from weight and P2, DXA-derived estimates remained accurate when between experiment variation was included. Incorporation of subregions into a whole body software analysis influenced DXA’s ability to predict fat tissue mass with the most accurate measurements achieved by placing the entire scan image in the left arm region of the regional analysis grid. These results demonstrate the efficacy of DXA as a nondestructive method for determining body composition in the live animal and carcass, and its greater accuracy than current routinely used methods. [Copyright &y& Elsevier]

Two hundred and twenty-four pigs (112 boars, 112 gilts) housed in pens of seven pigs per pen were used in a 2 × 2 × 2 factorial design, with the factors of vaccination with a gonadotropin-releasing factor (GnRF) vaccine (Improvac; 0 or 2 mL at 13 and 17 wk of age), porcine somatotropin (pST; 0 or 5 mg/d from 17 wk of age), and gender. Pigs were weighed and feed intake was measured from 17 wk of age until slaughter at 21 wk of age. Body composition was estimated by dual-energy X-ray absorptiometry in two focus pigs per pen at 17 and 21 wk of age. Testes and ovary weights at slaughter were decreased by Improvac treatment (P < 0.001), but were not altered by pST treatment (P > 0.44). Daily gain was lower for gilts than boars (1,128 vs. 1,299 g/d, P < 0.001) and was increased by pST (1,172 vs. 1,255 g/d, P = 0.003) and Improvac (1,150 vs. 1,276 g/d, P < 0.001) treatments. Feed intake (as-fed basis) was lower in gilts than in boars (2,774 vs. 3,033 g/d, P = 0.002), was decreased by pST (3,037 vs. 2,770 g/ d, P = 0.002), and was increased by Improvac treatment (2,702 vs. 3,105 g/d, P < 0.001). As a result of the differences in feed intake and daily gain, feed conversion efficiency (gain:feed) was lower for gilts than for boars (0.403 vs. 0.427 P = 0.025), was improved by pST (0.385 vs. 0.452, P < 0.001), but was unchanged by Improvac treatment (0.423 vs. 0.410, P = 0.22). Carcass weight was lower in gilts than in boars (75.3 vs. 77.0 kg, P = 0.012), was unchanged by pST treatment (75.9 vs. 76.4 kg, P = 0.40), and was increased by Improvac treatment (75.1 vs. 77.2 kg, P = 0.003). Lean tissue deposition rate was lower in gilts than in boars (579 vs. 725 g/d, P < 0.001), was increased by pST (609 vs. 696 g/d, P < 0.001) and by Improvac treatment (623 vs. 682 g/d, P = 0.014). Fat deposition rate tended to be lower in gilts than in boars (214 vs. 247 g/d, P = 0.063), decreased by pST treatment (263 vs. 198 g/d, P < 0.001), and increased by Improvac treatment... [ABSTRACT FROM AUTHOR]

• The starch in wheat is fermented more thoroughly than starch in maize. • Protection of wheat starch by sodium hydroxide reduces in vitro fermentation but not in vivo whole tract digestibility. • Heat stress reduces the digestibility of starch and dry matter of concentrate diets. • Treating wheat with NaOH mitigates the negative effects on digestion of organic matter and starch due by heat stress. Previous studies have suggested that feeding slowly fermentable grains might improve heat-tolerance in ruminants, due to increased post-rumen starch digestion and a reduction in the heat increment of feeding. During heat stress gastrointestinal function may be compromised which could impact on the site and extent of digestion. To characterize the in vitro rumen starch and DM disappearance of corn, wheat, and 3% NaOH-treated wheat grains, grain samples were incubated during 0, 5, 8, and 24 h at 39 °C in buffered rumen fluid. Then faecal pH and whole tract apparent starch, DM, and organic matter (OM) digestibility were determined in wethers fed, with either corn (CD), wheat (WD) or 3% NaOH- treated wheat (TWD) based diets during heat stress in two experiments. In experiment 1, 22 wethers were fed either CD or WD (n = 11 per diet) during three different stages in climate controlled rooms: stage 1 (TNFR), 7 days of thermoneutral conditions 18–21 °C and 40–50% relative humidity) and 1.3 times maintenance feed intake; stage 2 (HSFR), 7 days of heat stress (28–38 °C and 30–50% relative humidity) and feed intake as TNFR ; and stage 3 (HSFU), 7 days of heat stress as in HSFR stage and 1.5 times maintenance feed intake. In experiment 2, 31 wethers were fed either CD (n = 10), WD (n = 10) or TWD (n = 11) during three different stages with the same temperature and relative humidity regimes as experiment 1, however during TNFR and HSFR stages wethers received 1.7 times maintenance feed intake while in HSFU stage wethers received 2 times maintenance feed intake. After 24 h of incubation, untreated wheat had the fastest rate of starch and DM disappearance followed by 3% NaOH-treated wheat and corn grain (P < 0.001). Wethers fed CD had lower apparent starch (P < 0.001) and higher DM (P < 0.001) and OM (P < 0.001) digestibility than those fed WD, which was associated with lower faecal pH (P < 0.001) and higher faecal starch content (P < 0.001) than wheat diets. 3% NaOH treatment of wheat did not affect the whole tract starch digestibility of wheat being faecal pH and starch content of TWD like WD. At low feed intakes (1.3 times maintenance) there was no effect of heat stress on digestibility whereas at higher feed intakes heat stress reduced starch, OM, and DM digestibility. However, starch digestibility of TWD was similar to WD and metabolizable energy intake, DM and OM digestibility were higher. It is concluded that 3% NaOH treatment of wheat could reduce the rumen starch disappearance (in vitro condition) without reducing the whole tract starch digestibility (tested in vivo) of wheat in heat-stressed wethers. The study demonstrated the treated wheat with NaOH can be a strategy to increase OM digestibility and energy retention of wethers under heat stress. [ABSTRACT FROM AUTHOR]

• The n-alkane method accurately measured intake of cows fed both herbage and a partial mixed ration. • Discrepancies between estimated and measured intakes were 5.1 % or less. • Accuracy in estimating herbage DMI was slightly better when less herbage was fed. Estimation of dry matter intake (DMI) using the n-alkane technique was evaluated in lactating dairy cows fed fresh herbage and a partial mixed ration (PMR). Four dietary treatments were investigated in a 2 × 2 factorial experiment using 16 Holstein-Friesian dairy cows. Dietary treatments were combinations of low and high amounts of fresh herbage (8 or 14 kg DM/cow per day) and PMR supplement (6 or 12 kg DM/cow per day). The pre-experimental period was 14 days followed by a 10-day experimental period. Cows were housed in individual metabolism stalls to allow for accurate measurement of DMI and total fecal output. Fecal n-alkane recovery rates were calculated to determine the most accurate corrections for incomplete fecal n-alkane recovery. The n-alkane technique accurately estimated DMI when corrected for incomplete fecal recovery using both published recovery rates and recovery rates calculated in this experiment. The most accurate application of recovery rates was with those calculated for each combination of dietary treatments, compared with using an average recovery rate. This research has important implications for the future use of the n-alkane technique, especially in PMR feeding systems. The discrepancy between estimated (when treatment recovery rates were applied) and measured herbage DMI increased with the amount of herbage offered but was not affected by amount of PMR. It was also found that the recovery rates of all natural n-alkanes increased as the amount of herbage increased. This research demonstrates that the n-alkane technique can be used to accurately estimate individual cow intake when fresh herbage and PMR are offered separately, evidenced by strong Lin's concordance estimates. [ABSTRACT FROM AUTHOR]

Presents abstracts of articles on the topic of nutrient sources in the field of clinical nutrition. 'Flavonoide in Australian tea'; 'Comparison of n-3 polyunsaturated fatty acid contents of wild and cultured Australian abalone'; 'Omega-3 enrichment of chicken'; 'Influence of grazing or short-term grain feeding on polyunsaturated fatty acid concentrations of Australian beef.'

Presents abstracts of articles on cardiovascular health in the field of clinical nutrition. 'Improvement in plasma lipid levels (including lipoprotein (a)) after chronic soy comsumption may be linked to equol'; 'Mediterranean and low fat diets are associated with similar lipid levels at 1 year in patients with coronary heart disease on statin therapy.'