Search

Over the winter period, the low grass growth and availability in pasture-based dairy systems results in animals being housed and predominantly fed a diet of grass silage. There is limited availability of methane (CH4) data evaluating the impact of forage type on dairy cows over the pre-partum period. The objective of the current experiment was to evaluate the impact of feeding grass clover (GC) silage and grass-only (GO) silage on the dry matter intake (DMI) and enteric CH4 emissions of dairy cows pre-partum. A complete randomised block design was utilised for the 6-week experiment over two winter periods: from December 2020 to January 2021 and from December 2021 to January 2022. In each year, 30 non-lactating pregnant dairy cows were randomly allocated to two treatments (n = 15). In both years, cows in the GC treatment were offered grass clover bale silage, while cows in the GO treatment were offered grass-only pit silage. The DMI and gaseous emissions of individual animals were monitored daily using Hokofarm RIC (roughage intake control) feed stations and the GreenFeed technology. GC silage consistently had greater (p < 0.05) organic matter (OM) digestibility and lower (p < 0.05) neutral detergent fibre (NDF) and acid detergent fibre (ADF) contents when compared with GO silage. Cows in the GC treatment had significantly greater (p < 0.05) total DMI (TDMI) compared with cows in the GO treatment. The daily CH4 emissions (in grams per day) were not affected by treatment; however, cows in the GC treatment had reduced (p < 0.05) CH4 yield (in grams per kilogram TDMI). Offering dairy cows GC silage over the pre-partum period resulted in greater DMI with reduced CH4 yield when compared with cows offered GO silage. [ABSTRACT FROM AUTHOR]

Encounters between animals occur when animals are close in space and time. Encounters are important in many ecological processes including sociality, predation and disease transmission. Despite this, there is little theory regarding the spatial distribution of encounters and no formal framework to relate environmental characteristics to encounters. The probability of encounter could be estimated with resource selection functions (RSFs) by comparing locations where encounters occurred to available locations where they may have occurred, but this estimate is complicated by the hierarchical nature of habitat selection.We developed a method to relate resources to the relative probability of encounter based on a scale‐integrated habitat selection framework. This framework integrates habitat selection at multiple scales to obtain an appropriate estimate of availability for encounters. Using this approach, we related encounter probabilities to landscape resources. The RSFs describe habitat associations at four scales, home ranges within the study area, areas of overlap within home ranges, locations within areas of overlap, and encounters compared to other locations, which can be combined into a single scale‐integrated RSF. We apply this method to intraspecific encounter data from two species: white‐tailed deer (Odocoileus virginianus) and elk (Cervus elaphus) and interspecific encounter data from a two‐species system of caribou (Rangifer tarandus) and coyote (Canis latrans).Our method produced scale‐integrated RSFs that represented the relative probability of encounter. The predicted spatial distribution of encounters obtained based on this scale‐integrated approach produced distributions that more accurately predicted novel encounters than a naïve approach or any individual scale alone.Our results highlight the importance of accounting for the conditional nature of habitat selection in estimating the habitat associations of animal encounters as opposed to 'naïve' comparisons of encounter locations with general availability. This method has direct relevance for testing hypotheses about the relationship between habitat and social or predator–prey behaviour and generating spatial predictions of encounters. Such spatial predictions may be vital for understanding the distribution of encounters driving disease transmission, predation rates and other population and community‐level processes. [ABSTRACT FROM AUTHOR]

Gray fox (Urocyon cinereoargenteus (Schreber, 1775)) populations in portions of the eastern United States have experienced declines whose trajectories differ from those of other mesocarnivore populations. One hypothesis is that gray fox declines may result from interspecific interactions, particularly competition with abundant coyotes (Corns latrans Say, 1823). Alternatively, gray foxes may respond negatively to increased urbanization and reduced forest cover. To evaluate these hypotheses, we used single-species occupancy models of camera trap data to test the effects of habitat covariates, such as the amount of urbanization and forest, on coyote and gray fox occupancy. Additionally, we test the effect of an index based on an N-mixture model of the number of coyotes at each camera trap site on gray fox occupancy. Results indicate that occupancy probabilities of coyote and gray fox relate positively to the amount of forest, but they provided no evidence urban cover impacts gray foxes. Additionally, gray fox occupancy was negatively related to the index of the number of coyotes at each site. Our models support the idea that interactions with coyotes impact gray fox occupancy across the eastern United States. These results illustrate how large-scale studies can relate mechanisms identified within specific landscapes to phenomena observed at larger scales. Key words: Cams latrans, coyote, competition, gray fox, interspecific, mesopredator release, occupancy, Urocyon cinereoargenteus. Les populations de renards gris (Urocyon cinereoargenteus (Schreber, 1775)) dans certaines parties de l'est des Etats-Unis ont connu des baisses dont les trajectoires different de celles des populations d'autres mesocarnivores. Une hypothese pour expliquer ce phenomene veut que les declins de renards gris pourraient decouler d'interactions entre especes, plus particulierement la concurrence d'abondants coyotes (Canis latrans Say, 1823). II se pourrait par contre que les renards gris reagissent negativement a l'urbanisation accrue et a la diminution du couvert forestier. Afin d'evaluer ces hypotheses, nous avons utilise des modeles d'occupation d'espece unique appliques a des donnees de pieges photographiques pour examiner les effets de covariables associees a l'habitat, telles que la quantite d'espaces urbanises et de foret, sur l'occupation des coyotes et des renards gris. Nous avons egalement verifie l'effet d'un indice base sur un modele N-melange du nombre de coyotes a chaque site de piege photographique sur l'occupation par les renards gris. Les resultats indiquent que les probability d'occupation par des coyotes et des renards gris sont positivement reliees a la quantite de couvert forestier, mais ne revelent aucun signe d'une influence de la couverture urbaine sur les renards gris. L'occupation des renards gris est en outre negativement reliee a l'indice du nombre de coyotes dans chaque site. Nos modeles appuient l'idee selon laquelle les interactions avec les coyotes auraient une incidence sur l'occupation des renards gris dans l'est des Etats-Unis. Ces resultats illustrent comment des etudes a grande echelle peuvent permettre de relier des mecanismes observes dans des paysages precis a des phenomenes observes a plus grande echelle. [Traduit par la Redaction] Mots-cles : Canis latrans, coyote, concurrence, renard gris, interspecifique, liberation de mesopredateurs, occupation, Urocyon cinereoargenteus., Introduction Medium-sized carnivores, or mesocarnivores, may benefit from the extirpation of top predators and from being able to exploit modified landscapes (Prugh et al. 2009; Bateman and Fleming 2012). The [...]

Residual methane emission (RME) is a trait that has previously been identified as being independent of animal production traits. The objective of this study was to investigate the effect of ranking grazing dairy cows by RME on animal productivity and enteric methane (CH4) emissions. Milk production, dry matter intake (DMI), liveweight (LWT) and CH4 were recorded on grazing late lactation dairy cows at Teagasc Moorepark, Ireland. The dairy cows were producing 352 g CH4/day, while consuming 16.6 kg DM. The mean methane yield was 20.79 g CH4/kg DMI. Residual methane emission was calculated as the difference between measured CH4 yield and New Zealand emission factor (21.6 g CH4/kg DMI). These dairy cows were ranked based on their RME and classified into groups. The low RME group produced 15% less CH4 than the high RME group while maintaining milk production and feed conversion efficiency. The low RME group had lower methane yield, and methane intensity. There are no significant phenotypic correlations between RME and animal production traits such as energy corrected milk yield, or LWT. These results indicate that RME has the ability to select and rank low emitting grazing dairy cows while being independent from animal productivity traits. [ABSTRACT FROM AUTHOR]

Minerals are supplemented routinely to dairy cows during the dry period to prevent metabolic issues postpartum. However, limited information exists on the impacts of mineral supplementation on colostrum carotenoids. This study aimed to determine the effects of prepartum supplementation with three micro-nutrients; inorganic selenium (INORG), organic selenium (ORG) or rumen-protected choline (RPC) on the carotenoid content of bovine colostrum and transition milk (TM) from pasture-based dairy cows. A total of 57 (12 primiparous and 45 multiparous) Holstein-Friesian (HF) and HF × Jersey (JEX) cows were supplemented daily for 49 ± 12.9 d before calving. Colostrum samples were collected from all cows immediately postpartum and TM one to five (TM1–TM5) were collected from a sub-set of 15 cows (five per treatment group) at each consecutive milking postpartum. Carotenoid concentration was determined using ultra-high performance liquid chromatography – diode array detection (UHPLC-DAD). With the use of transmittance, the colour index and colour parameters a *, b * and L * were used to determine colour variations over this period. Prepartum supplementation did not have a significant effect on colostrum β-carotene concentration or colour. Positive correlations between β-carotene and colour parameter b * (R 2 = 0.671; P < 0.001) and β-carotene and colour index (R 2 = 0.560; P < 0.001) were observed. Concentrations of β-carotene were highest in colostrum (1.34 μg/g) and decreased significantly with each milking postpartum (TM5 0.31 μg/g). Breed had a significant effect on colostrum colour with JEX animals producing a greater b * colostrum than HF animals (P = 0.030). Primiparous animals produced colostrum with the weakest colour compared to second or ≥third parity animals (P = 0.042). Despite statistical increases in the b * parameter in colostrum from JEX cows and multiparous cows, β-carotene concentrations did not significantly increase suggesting that other factors may influence colostrum colour. The b * parameter may be used as an indicator for estimating carotenoid concentrations in colostrum and TM, particularly when assessed via transmittance spectroscopy. [ABSTRACT FROM AUTHOR]