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The proximity of rail corridors to livestock production enterprises poses potential risks to welfare and production. The association between these factors and production have been extensively investigated. This review aims to assess the potential impact on the basis of existing data in a livestock production context. Due to expansion of freight rail networks through agricultural land, there is a need to investigate potential impacts of rail (including train and track) noise, vibration and visual disturbance on the physiology and behaviour of the livestock and subsequent production traits. Additionally, the factors influencing the impact on animals were characterised broadly as noise, vibration, and visual and spatial disturbance. This information was used to develop conceptual frameworks around the contribution of rail impact on allostatic load, animal welfare and production. Placing rail noise in the context of other, known, noise impacts showed that proximity to the rail line will determine the impact of noise on the behaviour and physiology of the animal. Thresholds for noise levels should be determined on the basis of known noise thresholds, taking into account the impact of noise on allostatic load. Further research is recommended to investigate the behavioural, physiological and production impacts on livestock from proximity to rail corridors. Current literature suggests that the allostatic load will vary depending on the proximity of the animal to the source of stimulus, the type, size or level of stimuli, habituation and the individual animal variation in response to the stimuli. [ABSTRACT FROM AUTHOR]

A dose-response experiment was designed to examine the effect of 3-nitrooxypropanol (3-NOP) on methane (CH4) emissions, rumen function and performance of feedlot cattle fed a tempered barley-based diet with canola oil. Twenty Angus steers of initial body weight (BW) of 356 ± 14.4 kg were allocated in a randomized complete block design. Initial BW was used as the blocking criterion. Cattle were housed in individual indoor pens for 112 d, including the first 21 d of adaptation followed by a 90-d finishing period when five different 3-NOP inclusion rates were compared: 0 mg/kg dry matter (DM; control), 50 mg/kg DM, 75 mg/kg DM, 100 mg/kg DM, and 125 mg/kg DM. Daily CH4 production was measured on day 7 (last day of starter diet), day 14 (last day of the first intermediate diet), and day 21 (last day of the second intermediate diet) of the adaptation period and on days 28, 49, 70, 91, and 112 of the finisher period using open circuit respiration chambers. Rumen digesta samples were collected from each steer on the day prior to chamber measurement postfeeding, and prefeeding on the day after the chamber measurement, for determination of rumen volatile fatty acids (VFA), ammonium-N, protozoa enumeration, pH, and reduction potential. Dry matter intake (DMI) was recorded daily and BW weekly. Data were analyzed in a mixed model including period, 3-NOP dose and their interaction as fixed effects, and block as a random effect. Our results demonstrated both a linear and quadratic (decreasing rate of change) effect on CH4 production (g/d) and CH4 yield (g/kg DMI) as 3-NOP dose increased (P < 0.01). The achieved mitigation for CH4 yield in our study ranged from approximately 65.5% up to 87.6% relative to control steers fed a finishing feedlot diet. Our results revealed that 3-NOP dose did not alter rumen fermentation parameters such as ammonium-N, VFA concentration nor VFA molar proportions. Although this experimental design was not focused on the effect of 3-NOP dose on feedlot performance, no negative effects of any 3-NOP dose were detected on animal production parameters. Ultimately, the knowledge on the CH4 suppression pattern of 3-NOP may facilitate sustainable pathways for the feedlot industry to lower its carbon footprint. [ABSTRACT FROM AUTHOR]

Context: Cassava bagasse is readily available in tropical countries as an energy source for ruminant diets, but previous research has shown low cattle performance at high inclusion rates. Aims: The nature of the dose–response relationship between increasing inclusion rate of cassava (Manihot esculenta Crantz) bagasse (CB), substituting for protein meals in diets of fattening cattle, was used to evaluate the reduced animal performance at high inclusion rates. Methods: Thirty growing Madura (Bos indicus × javanicus) bulls were fed concentrate-based diets with five levels of CB inclusion at 20 g dry matter (DM)/kg liveweight and elephant grass (Pennesetum purpureum) separately at 5 g DM/kg liveweight. The five tested CB inclusion rates into the offered diet were 30, 40, 50, 60 and 70% of total dry matter. Lines of best fit were used to describe the relationships between animal performance and CB inclusion rate. Key results: Intake of dry matter and concentrate both demonstrated a quadratic relationship with increasing CB inclusion, both maximised at 46–47% CB inclusion in the offered diet or a CB intake of ~9.7 g CB/kg liveweight. Liveweight gain and change in body condition score both demonstrated a quadratic dose–response relationship with increasing CB inclusion, with maximal performance achieved at 34–38% inclusion of CB. Although protein content at the highest level of CB inclusion was low (68 g/kg DM), modelling of predicted liveweight gain indicated that this was most constrained by energy intake (as a function of concentrate intake), rather than crude protein. Conclusions: Inclusion of CB up to ~45% of the diet, substituting for protein meals, does not improve, but has no detrimental effect, on liveweight gain. The plateauing of CB intake above 50% inclusion in in the offered diet suggests that cattle were eating to a maximal CB intake. Several hypotheses for reduced intake of concentrate at high levels of CB inclusion were proposed, including low protein content and hydrogen cyanide content of the CB, none of which satisfactorily explained why intake of concentrate was depressed above 50% CB inclusion of the diet on offer. Implications: Rations should be formulated to contain no more than 50% CB for maximal cattle performance. Further research is required to understand the causes of depressed intake at high inclusion rates of CB. Cassava bagasse is a by-product feedstuff with potential as a ruminant feed in tropical environments, but there is poor understanding regarding production responses from its inclusion in cattle diets. We found that when cassava bagasse inclusion in a concentrate mix was increased, cattle intake of the concentrate mix increased, but in a curvilinear fashion. We suggest that cattle will eat no more than a maximal limit of cassava bagasse intake, although the reasons why are not clear. [ABSTRACT FROM AUTHOR]

Asparagopsis taxiformis (Asparagopsis) has been shown to be highly efficacious at inhibiting the production of methane (CH4) in ruminants. To date, Asparagopsis has been primarily produced as a dietary supplement by freeze-drying to retain the volatile bioactive compound bromoform (CHBr3) in the product. Steeping of Asparagopsis bioactive compounds into a vegetable oil carrier (Asp-Oil) is an alternative method of stabilizing Asparagopsis as a ruminant feed additive. A dose-response experimental design used 3 Asp-Oil-canola oil blends, low, medium, and high Asp-Oil which provided 17, 34, and 51 mg Asparagopsis derived CHBr3/kg dry matter intake (DMI), respectively (in addition to a zero CHBr3 canola oil control), in a tempered-barley based feedlot finisher diet, fed for 59 d to 20 Angus heifers (five replicates per treatment). On four occasions, live weight was measured and CH4 emissions were quantified in respiration chambers, and blood, rumen fluid, and fecal samples were collected. At the end of the experiment, all animals were slaughtered, with carcasses graded, and samples of meat and edible offal collected for testing of consumer sensory qualities and residues of CHBr3, bromide, and iodide. All Asp-Oil treatments reduced CH4 yield (g CH4/kg DMI, P = 0.008) from control levels, with the low, medium, and high Asp-Oil achieving 64%, 98%, and 99% reduction, respectively. Dissolved hydrogen increased linearly with increasing Asp-Oil inclusion, by more than 17-fold in the high Asp-Oil group (P = 0.017). There was no effect of Asp-Oil treatment on rumen temperature, pH, reduction potential, volatile fatty acid and ammonia production, rumen pathology, and histopathology (P > 0.10). There were no differences in animal production and carcass parameters (P > 0.10). There was no detectable CHBr3 in feces or any carcass samples (P > 0.10), and iodide and bromide residues in kidneys were at levels unlikely to lead to consumers exceeding recommended maximum intakes. Overall, Asp-Oil was found to be safe for animals and consumers of meat, and effective at reducing CH4 emissions and yield by up to 99% within the range of inclusion levels tested., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science.)