Influence of trough versus pasture feeding on average daily gain and carcass characteristics in ruminants: A meta-analysis

Review: Use and misuse of meta-analysis in Animal Science

In animal sciences, the number of published meta-analyses is increasing at a rate of 15% per year. This current review focuses on the good practices and the potential pitfalls in the conduct of meta-analyses in animal sciences, nutrition in particular. Once the study objectives have been defined, several key phases must be considered when doing a meta-analysis. First, as a principle of traceability, criteria used to select or discard publications should be clearly stated in a way that one could reproduce the final selection of data. Then, the coding phase, aiming to isolate specific experimental factors for an accurate graphical and statistical interpretation of the database, is discussed. Following this step, the study of the levels of independence of factors and of the degree of data balance of the meta-design represents an essential phase to ensure the validity of statistical processing. The consideration of the study effect as fixed or random must next be considered. It appears based on several examples that this choice does not generally have any influence on the conclusions of a meta-analysis when the number of experiments is sufficient.

Tropical grasslands: A pivotal place for a more multi-functional agriculture

Tropical grasslands represent a pivotal arena for the sustainable intensification of agriculture in the coming decades. The abundant ecosystem services provided by the grasslands, coupled with the aversion to further forest destruction, makes sustainable intensification of tropical grasslands a high policy priority. In this article, we provide an inventory of agricultural initiatives that would contribute to the sustainable intensification of the tropical grassland agro-ecosystem, and we recommend a shift in the scientific priorities of animal scientists that would contribute to realization of a more agro-ecological and multi-functional agriculture in the world's tropical grasslands.

A meta-analysis of nutrient intake, feed efficiency and performance in cattle grazing on tropical grasslands

It is essential to quantify the potential of tropical grasslands to allow significant feed efficiency for grazing livestock in controlled conditions such as at pasture. We conducted a quantitative analysis of published studies reporting the experimental results of average daily gains (ADG) and diet characteristics obtained specifically under grazing conditions (17 publications and 41 experiments), which have been less studied compared with controlled conditions in stalls. The database was analyzed to determine the average and range of values obtained for ADG (g/kg BW), dry matter digestibility, intake (DMI) and digestible DMI (DDMI, g/kg BW) and feed conversion efficiencies (FCE), as well as to predict the response of these parameters to the main strategies investigated in the literature - that is, mainly the stocking rate (SR) and the concentrate intake (CI). The ADG reached 1.2 kg BW per day and was directly linked to DDMI (ADG=-1.63+0.42 DDMI -0.0084 DDMI2, n=90, r.m.s.e=0.584, R 2=0.93). The DDMI, which was representative of the nutrient input, was driven mainly by DMI rather than dry matter digestibility, whereas these two parameters did not correlate (r=0.068, P=0.56). The average global FCE (0.11 g ADG/g DDMI) showed a greater association with the metabolic FCE (0.17 g ADG/g DMI) than the digestive FCE (0.62). The CI (g DM/kg BW) increased ADG (ADG=2376+CI 56.1, n=16, r.m.s.e.=441, R 2=0.95). The SR expressed as kg BW/ha decreased the individual ADG by 1.19 g/kg BW per additional ton of BW/ha, whereas the global ADG calculated per ha increased by 0.57 per additional ton BW/ha. When the SR was expressed as kg BW/ton DM and per ha rather than as kg BW/ha, the impact on the individual ADG decreased by 0.18 or 0.86 g per additional ton BW/ha, depending on the initial BW of the cattle. These results provide a better view of the potential performance and feeding of cattle in tropical grasslands. The results provide an improved quantification of the relationships between diet and performance, as well as the overall quantitative impact of SR and supplementation.

Virtual herding for flexible livestock management – a review

Free-ranging livestock play a pivotal role globally in the conversion of plant tissue into products and services that support man’s many and changing lifestyles. With domestication came the task of providing livestock with an adequate plane of nutrition while simultaneously managing vegetation for sustainable production. Attempting to meld these two seemingly opposing management goals continues to be a major focus of rangeland research. Demand for multiple goods and services from rangelands today requires that livestock production make the smallest possible ‘negative hoof-print’. Advancements in global navigation satellite system, geographic information systems, and electronic/computing technologies, coupled with improved understanding of animal behaviour, positions virtual fencing (VF) as an increasingly attractive option for managing free-ranging livestock. VF offers an alternative to conventional fencing by replacing physical barriers with sensory cues to control an animal’s forward movement. Currently, audio and electrical stimulation are the cues employed. When VF becomes a commercial reality, manual labour will be replaced in large part with cognitive labour for real-time prescription-based livestock distribution management that is robust, accurate, precise and flexible. The goal is to manage rangeland ecosystems optimally for soils, plants, herbivores in addition to the plant and animal’s microflora. However, maximising the benefits of VF will require a paradigm shift in management by using VF as a ‘virtual herder’ rather than simply as a tool to manage livestock within static physical barriers.