David W. Miller

This study tested the hypotheses that gamma-aminobutyric acid (GABA) supplementation in the drinking water, along with supplementation of glutamine (Gln), glutamate (Glu) and tryptophan (Trp) in the diet, would reduce indices of the stress response and improve growth performance in post-weaned piglets subjected to a mixing stress and short-term feed deprivation. At weaning, 72 entire male piglets were allocated to pens with their littermates (3 piglets/pen) and allowed to acclimate for 14 days, after which time they were allocated to a 2 x 2 factorial arrangement of treatments with factors being (1) with/without feed deprivation for 12 h (Fast, NoFast) and (2) with/without supplementation of the selected amino acids (Supplement, NoSupplement). All piglets were mixed with non-littermates at 0600 h on day 14 to create a mixing challenge, and at this time piglets were either taken off feed for 12 h (Fast) or were not deprived of feed (NoFast). At 1800 h on the same day, one half of the piglets was supplemented with 50 mg/day GABA in water (from days 14-18) and 0.3% L-Glu, 0.1% L-Gln and 0.34% L-Trp added to their diet (from days 14-21). From day 21 all piglets were fed the same diet without any supplementation, and the study finished on day 28. Weekly live weights and feed intakes were measured, blood was collected at days 11, 14 (1800 h) and 18, and a sugar absorption test (SAT) was conducted in Fast-NoSupplement piglets and Fast-Supplement piglets on days 14 and 22. On day 14, 12 h after treatments were imposed, plasma cortisol and non-esterified fatty acid concentrations were higher in Fast piglets compared to NoFast piglets (main effect; 10.5 vs 6.0 ng/ml, P = 0.09, and 0.34 vs 0.09 mmol/L, P < 0.001, respectively). Plasma glucose concentration at this time was higher in NoFast piglets compared to Fast piglets (main effect; 6.3 vs 5.7 mmol/L, P < 0.001); however, this difference was reversed by day 18 (6.6 vs 7.1 mmol/L, P < 0.01). A trend for a main effect for concentrations of brain-derived neurotrophic factor on day 14 (5.3 vs 2.6 ng/ml, P = 0.072), and a significant main effect on day 18 (5.6 vs 2.5 ng/ml, P = 0.008), were observed for piglets offered Supplement compared to piglets offered NoSupplement, respectively. At day 22, piglets offered Supplement tended to have a higher plasma D-mannitol concentration compared to NoSupplement piglets (174 vs 128 nmol/L, P = 0.09), and there was a trend for a positive change in citrulline concentration between days 14 to 22 between the Supplement and NoSupplement piglets (change, 11.2 vs 2.0 ng/ml, P = 0.092). Feed conversion ratio from day 15-21 was lower in Supplement piglets compared to NoSupplement piglets regardless of feed deprivation (main effect; 1.27 vs 1.42, P = 0.007). These results indicate that mixing stress and (or) short-term feed deprivation induces acute psychological and metabolic changes in piglets, and supplementation with this combination of selected amino acids can modulate aspects of intestinal function and improve feed efficiency after weaning.

This experiment examined whether multiparous sows fed a diet lower in energy and lysine at a reduced feed allowance would still mobilise fat and (or) protein to support piglet growth and negatively impact subsequent reproductive performance. A total of 152 multiparous sows was allocated in a 2 × 2 factorial design with the respective factors being diet type fed in lactation (gestation, 13.0 MJ digestible energy (DE)/kg, 0.42 g standardised ileal digestible (SID) lysine/MJ DE; or lactation, 14.3 MJ DE/kg, 0.62 g SID lysine/MJ DE) and feed allowance (ad libitum or 7.5 kg/d, ~15% reduction on ad libitum intake). Body composition was estimated on the day after farrowing (day 2) and at weaning (day 21). Blood was collected on days 2, 21 and at standing heat, for the analysis of insulin and insulin-like growth factor 1 (IGF-1). Diet type did not alter (p > 0.05) bodyweight or P2 backfat depth change in lactation, estimated body fat and protein changes, litter growth, or subsequent total piglets born. Ad libitum-fed sows showed a significant gain in girth compared to sows offered 7.5 kg/d (2.9 versus −0.4 mm, p = 0.015) and had a tendency for a shorter wean-to-service interval (p < 0.10). Sows fed the lactation diet had higher insulin concentrations at weaning (p < 0.05), but levels were the same (p > 0.10) by heat detection; IGF-1 concentrations remained unaffected. These data indicate that imposing a calculated negative energy and lysine balance on lactating sows had a limited impact on lactation or subsequent reproductive performance, supporting the notion that the modern sow may be more resilient to nutritional impositions than has been historically reported.

There is increasing interest from cattle lot-feeders in the use of shade to mitigate the effects of a potential heat stress event, though it is unclear whether the reported benefits of shade in previous studies conducted in more high-risk heat stress zones are pertinent in cooler temperate zones. The objectives of this study were to measure the welfare and performance benefits of shade provision for lot-fed cattle at a commercial feedlot located in a mild heat-stress risk zone in Western Australia. Six blocks of black Angus (Bos taurus) steers were inducted into the feedlot over six time-windows across a southern hemisphere summer, with 80 cattle per block housed in a partially shaded pen (providing 3.125 m² of shade per animal) and 80 in an unshaded pen. Parameters assessed in 960 cattle over the first 70 days in the feedlot included weight gain, feed intake, and physiological and behavioral indices of overall health and welfare. Over the months of October through to May in which the experiment was conducted, shaded cattle demonstrated a modest 0.13 kg overall increase in average daily gain across the 70-day feedlot period (P = 0.13). There was no difference in dry matter intake between any block or treatment. The physiological and behavioral markers of health and welfare revealed that, even during to hottest times of the experiment, the cattle were quite able to thermoregulate, via increased panting and seeking shade (if available), to maintain physiological homeostasis. In addition, we measured the effect of heat stress and shade provision on the affective state of the cattle. Qualitative behavioral assessment was used to indicate that the cattle in the ‘no stress’ temperature humidity index (THI) category and the shaded cattle in the ‘moderate stress’ THI category displayed the most positive demeanor (P < 0.05), being described as more ‘settled and sociable’, while the unshaded cattle in the ‘moderate stress’ THI category and all cattle in the ‘severe stress’ THI category were described as more ‘agitated/anxious’ (P < 0.05). Overall, the findings from the present study suggest that there are definite welfare and modest performance benefits associated with providing cattle with shade in summer in a feedlot situated in a temperate climatic zone.

Article Frontmatter was published on April 1, 2023 in the journal Moral Philosophy and Politics (volume 10, issue 1).

Article Frontmatter was published on April 1, 2022 in the journal Moral Philosophy and Politics (volume 9, issue 1).

There is significant public interest in the Australian live animal export industry and a need to develop a program that can measure and monitor animal welfare throughout the supply chain. An online survey of stakeholder opinions of this industry and animal welfare measures was carried out in 2015 with 921 respondents: 30% from the public who identified as animal welfare advocates (AWAs); 44% from the public who did not identify as AWAs (general public; GP); 26% live export industry (LEI) workers. AWA and GP respondents expressed greater concern than LEI respondents for animal welfare throughout the supply chain but had less concern for animals at Australian feedlots than in other parts of the supply chain. The majority of AWA and GP respondents believed data collected on animal welfare should be made public and should be collected by independent welfare officers and used to regulate the industry and impose penalties for poor welfare. LEI workers believed that data should be confidential, collected by LEI workers and used by the industry to self-regulate. AWA and GP respondents rated the importance and practicality of a number of welfare indicators greater than LEI workers, while respondents shared an analogous view of the importance and practicality of these indicators. Results can be used to develop welfare assessments that ensure a better understanding between industry members and those not in the industry, while facilitating welfare improvements and promoting greater transparency for the live export industry.

Dietary tryptophan (Trp) is a precursor for serotonin, a neuromediator involved in stress responses. Tryptophan competes with other large neutral amino acids (LNAA: tyrosine, isoleucine, leucine, valine, and phenylalanine) to cross the blood–brain barrier; therefore, the regulation of circulating LNAA can influence Trp availability in the cortex and serotonin biosynthesis. The hypothesis examined in this study was that increased supplementation of dietary Trp and a reduction in LNAA for weaned pigs experimentally infected with enterotoxigenic Escherichia coli (ETEC; F4) will increase Trp availability in plasma and reduce indices of the stress response, which will translate to reduced production losses. At 21 ± 3 d of age (mean ± SEM), 96 male pigs (Large White × Landrace) weighing 6.3 ± 0.98 kg (mean ± SEM) were individually penned and allocated to a 4 × 2 factorial arrangement of treatments, with respective factors being 1) four dietary standardized ileal digestible (SID) Trp and LNAA contents, being H_TrpHLNAA (Low Trp-High LNAA; 0.24% SID Trp: 5.4% SID LNAA), H_TrpHLNAA (Low Trp-Low LNAA; 0.24% SID Trp: 4.6% SID LNAA), H_TrpHLNAA (High Trp-High LNAA; 0.34% SID Trp: 5.4% SID LNAA), and H_TrpHLNAA (High Trp-Low LNAA; 0.34% SID Trp: 4.6% SID LNAA), and 2) without/with ETEC infection. Pigs were orally infected with 0.8 mL (3.6 × 10⁹ CFU/mL) ETEC at days 7 and 8 after weaning. Pigs fed diets high in Trp irrespective of the level of LNAA (H_TrpH_LNAA and H_TrpL_LNAA) had higher plasma Trp concentrations (P < 0.001) and a Trp:LNAA ratio (P < 0.001) before infection and 6 d after infection. Following infection, noninfected pigs had higher plasma Trp (P = 0.03) and a Trp:LNAA ratio (P = 0.004) compared with pigs infected with ETEC. Plasma cortisol levels after infection were higher in ETEC-infected pigs (P = 0.05) and altering dietary Trp and LNAA concentrations did not influence (P > 0.05) plasma cortisol. Pigs fed diet H_TrpL_LNAA had higher serum serotonin levels 24 h after infection (P = 0.02) compared with pigs fed diets L_TrpL_LNAA and H_TrpH_LNAA. Similarly, pigs fed diet H_TrpL_LNAA had a higher (P = 0.02) average daily gain during the 3-wk study. Overall, average daily feed intake tended to be higher in pigs fed an H_TrpL_LNAA diet compared with the other diets (P = 0.08). These results suggest that the increased supplementation of dietary Trp with reduced LNAA increased circulating Trp levels that, in turn, likely caused higher serum serotonin levels, irrespective of infection with ETEC, and improved aspects of post-weaning performance.

Animal welfare is an important issue for the live export industry (LEI), in terms of economic returns, community attitudes and international socio-political relations. Mortality has traditionally been the main welfare measure recorded within the LEI; however, high mortality incidents are usually acted upon after adverse events occur, reducing the scope for proactive welfare enhancement. We reviewed 71 potential animal welfare measures, identifying those measures that would be appropriate for use throughout the LEI for feeder and slaughter livestock species, and categorised these as animal-, environment- and resource-based. We divided the live export supply chain into three sectors: (1) Australian facilities, (2) vessel and (3) destination country facilities. After reviewing the relevant regulations for each sector of the industry, we identified 38 (sector 1), 35 (sector 2) and 26 (sector 3) measures already being collected under current practice. These could be used to form a ‘welfare information dashboard’: a LEI-specific online interface for collecting data that could contribute towards standardised industry reporting. We identified another 20, 25 and 28 measures that are relevant to each LEI sector (sectors 1, 2, 3, respectively), and that could be developed and integrated into a benchmarking system in the future.

The identification and assessment of pain in sheep under field conditions are important, but, due to their stoic nature, are fraught with many challenges. In Australia, various husbandry procedures that are documented to cause pain are routinely performed at lamb marking, including ear tagging, castration, mulesing, and tail docking. This study evaluated the validity of a novel methodology to assess pain in lambs: qualitative behavioural assessment (QBA) was used to compare the behavioural expression of control lambs (CONTROL) with that of lambs subject to these procedures that received either a saline placebo 15 min before procedures (PLACEBO), or were administered meloxicam 15 min before procedures in addition to the standard analgesic Tri-Solfen at the time of procedures, as per the manufacturer’s recommendations (ANALGESIC TREATMENT; AT). In terms of behavioural expression, it was expected that: CONTROL ≠ PLACEBO, AT = CONTROL, and PLACEBO ≠ AT. Video footage of the 6−8-week-old lambs (n = 10 for each treatment) was captured approximately 1.5 h postprocedure and was presented, in a random order, to 19 observers for assessment using the Free-Choice Profiling (FCP) approach to QBA. There was significant consensus (p < 0.001) among the observers in their assessment of the lambs, with two main dimensions of behavioural expression explaining 69.2% of the variation. As expected, observers perceived differences in the demeanour of lambs in the first dimension, scoring all lambs subject to the routine husbandry procedures as significantly more ‘dull’ and ‘uneasy’ compared to the control lambs (p < 0.05). Contrary to expectations, the results also suggested that analgesic treatment did not provide relief at the time of observation. Further investigations to validate the relationship between behavioural expression scores and pain are necessary, but these results suggest that painful husbandry procedures alter the behavioural expression of lambs and these differences can be captured using QBA methodology.