J. Komen

Hand-stripping of semen and semen quality after maturational hormone treatments, in African catfish Clarias gariepinus

Abstract In the hatchery-bred African catfish, Clarias gariepinus, spontaneous semen release does not occur and hand-stripping is practically impossible. This reproductive dysfunction may be due to a lack of a pre-spawning gonadotropin (luteinizing hormone—LH) surge. To test this hypothesis, the effects of hormones that increase plasma LH levels were analyzed. Mammalian gonadotropin releasing hormone analogue (mGnRHa), mGnRHa plus pimozide, a dopamine antagonist (mGnRHa-PIM), ovaprim (salmon GnRHa plus domperidone, a dopamine antagonist), carp pituitary suspension (carp-PS), Clarias pituitary suspension and combinations of carp-PS and ovaprim were tested. Stripped fluid, when present, was compared to intratesticular semen, 12 or 24 h after injection (latency time). Plasma LH levels increased (P

The influence of feeding history on the acute stress response of common carp (Cyprinus carpio)

Abstract The effect of an 80-day maintenance-feeding period on the acute stress response of common carp, Cyprinus carpio, to net confinement was determined. Fish were raised on an optimal feeding level of 20 g food/kg of metabolic fish weight per day (g/kg0.8 day−1) until 124 days post-hatch (dph). Feeding in group one (L>H) was then reduced to maintenance levels, i.e. 5 g/kg0.8 day−1 until 204 dph, when the feeding was again increased to 20 g/kg0.8 day−1. In group two (H>L), the feeding level was reduced from 20 to 5 g/kg0.8 day−1 on day 146. All fish were sampled at 226 dph. Food ration had significant effects on the growth rate and food conversion values with fish fed the high ration performing better than those on a lower level. Prior to the application of the stressor, only plasma levels of triglycerides were lower in fish fed a low food ration (H>L). Feeding history influenced the onset of the stress response with stressor-induced elevations of plasma cortisol, glucose and free fatty acids being higher in fish fed a high ration compared with those fed a low ration prior to sampling. These results suggest that feeding history through modification of the energy reserves can influence the onset of the acute stress response.

Comparison of growth performances of three French strains of common carp (Cyprinus carpio) using hemi-isogenic scaly carp as internal control

Three strains of mirror carp originating from important regions of carp culture in France (Brenne, Dombes, Forez) were compared for growth at 5 weeks, 1 summer and 2 summers of age in ponds using a paternal cross on the same Dombes dams. An internal scaly control was produced by crossing an homozygous inbred strain on the same dams and mixed with the tested strains in all ponds in a proportion of 1:3. No between-strain differences in weight were seen at any time when taking into account the weight of the internal control. However, the internal control weight at 2 summers of age was lower than that of the tested strains (P<0.05). The use of the internal control divides the number of replicates needed to have a good statistical power by 5 at 5 weeks and by 8 at 2 summers, when compared to separate testing without control. No genotype by environment or strain-control interactions were detected. The validity and optimisation of the use of an internal control in strain testing are discussed.

Exploring the genetic background of stress using isogenic progenies of common carp selected for high or low stress-related cortisol response

Abstract Four homozygous (HomIso) and eight heterozygous isogenic (HetIso) strains of common carp were used in two separate experiments to examine the genetic background of a stress-related cortisol response due to a rapid temperature decrease. The homozygous sires (two high and two low) and dams (high and low) used to obtain the strains were selected based on their estimated breeding value for this trait at an age of 15 months (EBV15). In both experiments, the strains were subjected to a 9 °C cold shock at an age of 5 months. The ranking in plasma cortisol levels of the HomIso strains was identical to the ranking in EBV15 of the sires and the maximal difference of 350 nmol l−1 was similar to the expected difference based on these EBV15s. Differences between the HetIso strains were smaller than expected, and influence of non-additive genetic effects could not be detected (PDS=0.14). Estimated breeding values based on the performance of the androgenetic progeny (EBV5) in experiment 1 and general combining abilities (GCA) of the sires and dams calculated in experiment 2 were positively correlated with the EBV15 (r not significantly different from 1), providing no evidence that the stress response at 5 and 15 months are different traits. Based on the results of these experiments, it can be argued that the best method to change the stress responsiveness of common carp would be through selective breeding (exploiting additive genetic effects) rather than through crossbreeding (exploiting non-additive genetic effects).

Desired genetic gains for a breeding objective: A novel participatory approach

Maternal abilities and piglet vitality were analyzed on 24 Meishan (MS) and 24 Large White (LW) gilts. Females were inseminated with a mixture of semen from both breeds. Three MS and 3 LW boars were used to constitute 3 duos formed by mixing of MS and LW semen in equal proportions. Farrowing events were studied over 5 successive batches. The proportion of purebred and crossbred piglets within the litter varied according to the duo used and the dam breed (p<0.01). The average within-litter percentage of purebred piglets in LW and MS sows was respectively 43% and 50% with use of duo 1, 64% and 23% with duo 2 and 69% and 81% with duo 3. Gestation was shorter in MS than in LW sows (111.6 vs 114.0 days; p<0.05) and litter size tended to be larger in LW than in MS sows (14.6 vs 12.8 total born piglets; p=0.08). Over the three first days of lactation, piglet probability of survival was similar between purebred and crossbred piglets born from LW sows (94.5% vs 95.0%) and higher in purebred than crossbred piglets born from MS sows (96.6% vs 98.7%, p<0.05). In LW sows, crossbred piglets were heavier at birth and more reactive in a novel environment than purebred piglets (1.29 vs 1.21 kg, p<0.10; reactivity score: 1.38 vs 1.03 respectively). In MS sows, purebred piglets had a lower birth weight than crossbred piglets but showed similar vitality (0.86 vs 1.08 kg, p<0.001; reactivity score: 1.00 vs 1.03). Birth process and piglet behavior in early lactation will be analyzed to estimate the interaction between dam breed and piglet genetic type (purebred vs crossbred) on the expression of maternal behavior and piglet vitality (udder activity and survival).Young horses normally live in small year-round stable groups including one stallion, their mothers, a few other mares, their siblings and unrelated peers. On the contrary, most of young domestic horses are generally maintained in same-age and same-sex groups from weaning until training. One has to consider that the absence of adult partners during ontogeny may be a source of behavioral disorders. In a first study, we focused on social conditions at weaning. While it is well known that presence of peers is of high importance to alleviate weaning stress, we investigated here the effects of the introduction of unrelated adult mares in groups of weanlings. Results showed that signs of stress were less pronounced and shorter in time in weanlings housed with adult mares than in weanlings kept in same-age groups (e.g. distress vocalizations: P<0.05; salivary cortisol: P<0.05). Besides, only foals deprived of adult presence exhibited increased aggressiveness towards peers (P<0.05) and abnormal behaviors (P<0.05). In conclusion, the presence of two unrelated adults in groups of weanlings not only alleviated weaning stress, but also favored positive social behavior and limited the emergence of abnormal behaviors. In a second study, we examined the impact of the temporary presence of adult horses on the behavior of 1- and 2-year-old horses. Results showed that young horses reared in homogeneous groups had a reduced behavioral repertoire, no real preferred partner and displayed many agonistic interactions compared to domestic horses reared under more natural conditions. Interestingly, after the introduction of adults, young horses expressed new behaviors (e.g. snapping, lying recumbent), preferential social associations emerged (P<0.05) and positive social behavior increased (P<0.05). Taken together, these results have important implications in terms of husbandry, indicating the importance of keeping young horses with adults.The aim of this work was to characterise the European consumer of pig meat (within ALCASDE project). A total of 822 respondents participated in a survey that was carried out Germany (DE n=132), Spain (ES n=133), France (FR n=139), Italy (IT n=140), Netherlands (NL n=132) and United Kingdom (UK n=146). All of them were selected for consuming pork > 1 time/month and stratified by age and gender, within each country profile. Respondents answered socio-demographic questions and frequency of consumption of different pork products, the most common purchasing place for fresh pork meat, if they were responsible for buying fresh pork at home, if they were responsible for cooking at home, and if they usually eat the pork with the fat. Data was analysed with FREQ procedure of SAS software. In general, over ninety percent of consumers ate fresh pork > 2 times/week (DE 96.2 %; ES 95.5 %; IT 92.9 %; NL 93.9 %; UK 97.3 %) except for FR (34.8 %). The most consumed product was the sausage in DE, dry cured ham in ES and IT; cooked ham in FR, mince meat in NL and sliced bacon in UK. In all the countries, the supermarket was the most common purchasing place of fresh pork with the exception of NL, where it was the traditional market. In general, the percentage of respondents responsible for buying fresh pork in their household was 91.0 %. In all countries, women were more responsible for buying fresh pork than men, and they were mostly between 41-60 years old. Ninety-one percent of respondents were partially responsible for cooking at home. Women were more responsible for cooking at home than men. France was an exception, where 49.6 % women and 50.4 % men cooked at home. Considering all respondents, 44.5 % ate the pork with the fat in all the countries (35.4 % of women and 54.6 % of men). The study showed differences among countries regarding respondents’ traits.