Towards ethically improved animal experimentation in the study of animal reproduction

Nutritional Strategies to Promote Bovine Oocyte Quality for In Vitro Embryo Production: Do They Really Work?

The ability of bovine oocytes to reach the blastocyst stage (i.e., embryo with around 150 cells in cattle) in vitro can be affected by technical (e.g., culture medium used) and physiological factors in oocyte donors (e.g., age, breed). As such, the nutritional status of oocyte donors plays a significant role in the efficiency of in vitro embryo production (IVEP), and several nutritional strategies have been investigated in cattle subjected to ovum pick-up (OPU). However, there is no clear consensus on the reliability of nutritional schemes to improve IVEP in cattle. Available evidence suggests that a moderate body condition score (i.e., 3 in a 1-5 scale) in cattle is compatible with a metabolic microenvironment in ovarian follicles that will promote embryo formation in vitro. The usefulness of fatty acid and micronutrient supplementation to improve IVEP in cattle is debatable with the current information available. Overall, the supply of maintenance nutritional requirements according to developmental and productive stage seems to be enough to provide bovine oocyte donors with a good chance of producing embryos in vitro. Future nutrition research in cattle using OPU-IVEP models needs to consider animal well-being aspects (i.e., stress caused by handling and sampling), which could affect the results.

Association of steroid 17-alpha-hydroxylase/17,20 lyase (CYP17) single nucleotide polymorphism (SNP) 628 and dopamine receptor D2 (DRD2) SNP939 genotypes with sheep reproductive performance

In a previous study we investigated the association between two single nucleotide polymorphism (SNP) genotypes, namely steroid 17-alpha-hydroxylase/17,20 lyase (CYP17) SNP628 and dopamine receptor D2 (DRD2) SNP939, with two temperaments (calm and nervous) in Australian Merino sheep and concluded that the DRD2 SNP939 T/T genotype combined with the CYP17 SNP628 G/G genotype is associated with a calm temperament and could be used as a potential marker for calm sheep, whereas the DRD2 SNP939C allele combined with the CYP17 SNP628 A/A genotype is associated with a nervous temperament and could be used as a potential marker for nervous sheep. In sheep, the association between temperament and reproductive performance has been determined, but the association of these two SNP genotypes with sheep reproduction has not been investigated. Therefore, using Chinese Sinkiang Merino sheep, the present study investigated the association of the two CYP17 SNP628 and DRD2 SNP939 genotypes with sheep reproductive performance. Sheep with the DRD2 SNP939 T/T genotype combined with the CYP17 SNP628 G/G genotype had a higher ovulation rate, multiple gestation rate, better maternal behaviour and lower lamb mortality. Thus, the results of this study contribute to our knowledge of the association between genotypes and reproduction in sheep, which is beneficial for sheep genetics and breeding.

Animal experimental research design in critical care

Background

Limited translational success in critical care medicine is thought to be in part due to inadequate methodology, study design, and reporting in preclinical studies. The purpose of this study was to compare reporting of core features of experimental rigor: blinding, randomization, and power calculations in critical care medicine animal experimental research. We hypothesized that these study design characteristics were more frequently reported in 2015 versus 2005.

Methods

We performed an observational bibliometric study to grade manuscripts on blinding, randomization, and power calculations. Chi-square tests and logistic regression were used for analysis. Inter-rater agreement was assessed using kappa and Gwet’s AC1.

Results

A total of 825 articles from seven journals were included. In 2005, power estimations were reported in 2%, randomization in 35%, and blinding in 20% (n = 482). In 2015, these metrics were included in 9, 47, and 36% of articles (n = 343). The increase in proportion for the metrics tested was statistically significant (p < 0.001, p = 0.002, and p < 0.001).

Conclusions

Only a minority of published manuscripts in critical care medicine journals reported on recommended study design steps to increase rigor. Routine justification for the presence or absence of blinding, randomization, and power calculations should be considered to better enable readers to assess potential sources of bias.

Emotionality modulates the effect of chronic stress on feeding behaviour in birds

Chronic stress is a long-lasting negative emotional state that induces negative consequences on animals' psycho-physiological state. This study aimed at assessing whether unpredictable and repeated negative stimuli (URNS) influence feeding behaviour in quail. Sixty-four quail were exposed to URNS from day 17 to 40, while 64 quail were undisturbed. Two lines divergently selected on their inherent emotionality were used to assess the effect of genetic factors on the sensitivity to URNS. All quail were submitted to a sequential feeding procedure (using two diets of different energetic values) which placed them in a contrasting situation. Behavioural tests were performed to assess the emotional reactivity of the two lines. Results confirmed that differences exist between them and that their emotional reactivity was enhanced by URNS. Diet preferences, motivation and daily intake were also measured. URNS did not change the preferences for the hypercaloric diet compared to the hypocaloric diet in choice tests, but they reduced daily intakes in both lines. Motivations for each diet were differently affected by URNS: they decreased the motivation to eat the hypercaloric diet in quail selected for their low inherent fearfulness whereas they increased the motivation to eat the hypocaloric diet in quail selected for their high inherent fearfulness, which suggested a devaluation process in the former and a compensatory behaviour in the later. Growth was furthermore reduced and laying delayed by URNS in both lines. In conclusion, the exposure to URNS induced interesting changes in feeding behaviour added with an increase in emotional reactivity and an alteration of production parameters. This confirms that both lines of quail experienced a chronic stress state. However differences in feed motivation and emotional reactivity between lines under chronic stress suggested that they experienced different emotional state and use different ways to cope with it depending on their genetic background.

Disparate effects of feeding on core body and adipose tissue temperatures in animals selectively bred for Nervous or Calm temperament

In addition to homeostatic regulation of body mass, nonhomeostatic factors impact on energy balance. Herein we describe effects of temperament on adipose and core body temperatures in sheep. Animals were genetically selected for Nervous or Calm traits. We characterized the effects of 1) high- and low-energy intake and maintenance feeding, 2) meal anticipation, and 3) adrenocorticotropin challenge on core body and adipose temperatures. Temperature measurements (5 min) were made using a thermistor inserted into the carotid artery (core body) and a probe in the retroperitoneal fat. An imposed feeding window was used to establish postprandial elevations in temperature. Fat tissue was taken from retroperitoneal and subcutaneous regions for real-time PCR analyses. We demonstrate that innate differences in temperament impact on adipose and core body temperatures in response to various dietary and evocative stimuli. In response to homeostatic cues (low-energy intake and maintenance feeding) core body temperature tended to be higher in Calm compared with Nervous animals. In contrast, in response to nonhomeostatic cues, Nervous animals had higher anticipatory thermogenic responses than Calm animals. Expression of uncoupling protein (UCP)-1 and -2 mRNA were higher in retroperitoneal tissue than in subcutaneous tissue, but UCP3 and leptin mRNA levels were similar at both sites; expression of these genes was similar in Nervous and Calm animals. There were no differences in stress responsiveness. We conclude that temperament differentially influences adipose thermogenesis and the regulation of core body temperature in responses to both homeostatic and nonhomeostatic stimuli.