Fabienne Blanc

Effects of stocking density on the behaviour and growth of farmed red deer hinds

Abstract The aim of this experiment was to measure the effects of stocking density on the social behaviour, activity patterns and growth rates of yearling red deer hinds reared at pasture. Twenty individuals were assigned to two groups of 10 in a latin square design. During period 1 (28 days), group 1 was kept at a low stocking density (LD: 37 animals/ha) and group 2 at a high stocking density (HD: 150 animals/ha). During period 2 (28 days) the groups were switched and tested at the other stocking density. Aggressive encounters (kicks, bites and butts) and vigilance postures were more frequent at HD than at LD. There was no difference between the two densities in the total time spent grazing per day, but the hinds at HD had shorter and more frequent meals than the hinds at LD. The synchronisation of grazing was also lower at HD than at LD. The hinds grew faster at LD than at HD. The effects of stocking density on growth and grazing behaviour were more severe for subordinate than for dominant hinds. In conclusion, high stocking density induced a social stress that affected grazing patterns and growth rates, especially in subordinate individuals.

Effects of mixed-species stocking and space allowance on the behaviour and growth of red deer hinds and ewes at pasture

Abstract Our objective was to test whether the effects of space allowance on social interactions, activity patterns and growth rates of hinds reared at pasture in single-species groups, were modified by mixing them with ewes. Thirty individuals of each species were assigned to two single-species groups of 10 animals (hinds: H1 and H2, ewes: E1 and E2) and to two mixed-species groups of 5 hinds and 5 ewes (M1 and M2). For 28 days, H1, E1 and M1 were kept at high space allowance (HSA: 267 m 2 /animal) and H2, E2 and M2 at low space allowance (LSA: 67 m 2 /animal) and for the following 28 days, the space allowance was reversed. Mean interindividual distances in single-species groups were lower at LSA than at HSA (hinds: 10.0±0.3 vs. 15.4±4.8 m, P P P P P

Data-derived reference profiles with corepresentation of progesterone, estradiol, LH, and FSH dynamics during the bovine estrous cycle

Subfertility in cows is often associated with alterations in the hormonal patterns involved in the regulation of the estrous cycle. Reference profiles are needed to ground modeling projects aimed at describing these alterations and to develop tools for detecting abnormal dynamics. Various schematic views of LH, FSH, progesterone (P4) and estradiol (E2) patterns have been published but with no clear indication of the extent to which they are derived from real data. The objective of this study was to generate standard profiles for the main reproductive hormones that can be proposed as reliable references to represent the normal dynamics of these hormones over the estrous cycle. A database of hormonal profiles was compiled with 40, 23, 33, and 34 profiles for LH, FSH, E2, and P4, respectively, derived from publications in which changes over time of at least three of these four hormones, including LH, were reported. These profiles were digitalized and standardized over the time throughout the estrous cycle, considering the interval between two successive LH surges to be 21 days. After this standardization on the x-axis, a transformation on the y-axis was performed to center the profiles around their common dynamics. For each hormone, the reference profile was then considered to be the median of the adjusted profiles. Quartiles were reported to account for the time evolution of the variability around each reference profile. The reference profiles obtained showed that the procedure used was satisfactory for extracting the overall changes over time of LH, P4, and E2. Results were less satisfactory for FSH, because of a higher variability observed between the original profiles in our database. The corepresentation of the reference profiles, i.e., when depicted together on the same scale, emphasizes the interplay between these hormones more precisely than most of the schematic views available in literature. These data-derived profiles can be considered to be generic and useful for benchmarking the normal dynamics of gonadotrophins and steroid hormones over the estrous cycle in cow.

SIMBAL: a herd simulator for beef cattle

A beef cattle herd simulator was designed and developed as a tool for testing the consequences of farm management practices on herd performance. This discrete-event simulator is stochastic and individually based. It integrates a detailed reproduction model together with parameter-settable practices. This article details the various core components of the simulator. We then used it on virtual experiments with a herd of 70 cows. The first virtual experiment compared an autumn calving system with a herd management system based on winter calving. Adapting the herd management rules made it possible for the two systems to give similar outputs. In order to show the importance of the number of mated cows and of the reproductive period length on the performance of the herd, two different strategies were tested in with two new virtual experiments. The first one consisted in reducing the number of mated cows while the second one deals with reducing the reproduction period when the bull is present. The first of these scenarios led to drop in herd size in proportion with the female reduction over the years, whereas under the second scenario, a gap is simulated and the herd was wiped out after 10 years. We also focused an in-depth analysis on the variability of the results. The model shows that an average result not only masks variations from replication to replication but also masks variations in performances from year to year.