Acceptance of novel food by horses: The influence of food cues and nutrient composition

Compared to ruminants little is known about how horses modulate food intake and learn about flavour-to-post-ingestive consequences. While it has been suggested that due to hindgut fermentation horse’s foraging preferences may be largely influenced by sensory input (e.g. volatiles), it has been established that horses are able to differentiate and select familiar foods (e.g. concentrates and hay) based on nutritional content. Yet it remains unclear how this translates to the acceptance of nutritious novel foods (NF). Therefore, the influence of food cues and nutrient composition on NF acceptance were examined in two experiments using 11 adult mares. In experiment 1, we investigated the influence of a familiar odour (FO) on the acceptance of a nutritious NF and in experiment 2, we determined if horses have the ability to select nutritious NF based on the nutritional content, regardless of sensory preferences. In experiment 1 horses received identical NF in a two-choice test with one of the choices being masked with a FO over a 9-day period. In experiment 2 horses were offered a high or low protein option of an otherwise identical NF in a two-choice test in which the NFs were paired with two unfamiliar flavours (odours). The two-choice test lasted for 14 days and the flavour-protein pairing was switched after 7 days. NF intakes were recorded over a 10 min test period on each test day and analysed using Bayesian hierarchical models. The results of experiment 1 indicate that a FO had a strong positive influence on the NF intake for the first 5 days (90–100% of total consumption and strong evidence for non-zero temporal effects (Bayes factor B12 = 110)). This was followed by a more even distribution of intake for the remaining period. In experiment 2 horses had a greater intake of high protein NF regardless of the flavour on days 4, 6 and 7 (80–87% of total consumption) and this continued after the switch over (Day 9–14; 57–81% of total consumption). However, 4 out of 11 horses showed neophobia throughout the testing period, which could have been associated with the novel odours as horses scanned the buckets with little to no sampling. The results suggest that pre-ingestive cues (e.g. smell, taste) of foods play an important role in diet selection and that a FO can increase the acceptance of NF. This new knowledge could be applied by the horse industry to encourage the consumption of new food or forages by horses

Heterogeneity of variance components for preweaning growth in Romane sheep due to the number of lambs reared

<p>Abstract</p> <p>Background</p> <p>The pre-weaning growth rate of lambs, an important component of meat market production, is affected by maternal and direct genetic effects. The French genetic evaluation model takes into account the number of lambs suckled by applying a multiplicative factor (1 for a lamb reared as a single, 0.7 for twin-reared lambs) to the maternal genetic effect, in addition to including the birth*rearing type combination as a fixed effect, which acts on the mean. However, little evidence has been provided to justify the use of this multiplicative model. The two main objectives of the present study were to determine, by comparing models of analysis, 1) whether pre-weaning growth is the same trait in single- and twin-reared lambs and 2) whether the multiplicative coefficient represents a good approach for taking this possible difference into account.</p> <p>Methods</p> <p>Data on the pre-weaning growth rate, defined as the average daily gain from birth to 45 days of age on 29,612 Romane lambs born between 1987 and 2009 at the experimental farm of La Sapinière (INRA-France) were used to compare eight models that account for the number of lambs per dam reared in various ways. Models were compared using the Akaike information criteria.</p> <p>Results</p> <p>The model that best fitted the data assumed that 1) direct (maternal) effects correspond to the same trait regardless of the number of lambs reared, 2) the permanent environmental effects and variances associated with the dam depend on the number of lambs reared and 3) the residual variance depends on the number of lambs reared. Even though this model fitted the data better than a model that included a multiplicative coefficient, little difference was found between EBV from the different models (the correlation between EBV varied from 0.979 to 0.999).</p> <p>Conclusions</p> <p>Based on experimental data, the current genetic evaluation model can be improved to better take into account the number of lambs reared. Thus, it would be of interest to evaluate this model on field data and update the genetic evaluation model based on the results obtained.</p