Julie Gatien

Comparison of three devices for the automated detection of estrus in dairy cows

Considerable technological advances have been made in the automated detection of estrus in dairy cattle, but few studies have evaluated their relative performance on the same animals or assessed cow-related factors that affect their performance. Our objective was to assess the performance and reliability of three devices commercially available in France for cow estrus detection. The devices were a pedometer (PM; Afitag) and two activity meters (AM1; Heatime-RuminAct, and AM2; HeatPhone). Two algorithms were tested for AM2. We fitted 63 lactating Holstein cows with the three detectors from calving to 90 days after calving. The onset and pattern of cyclicity were monitored from 7 to 90 days postpartum measuring progesterone concentration in milk twice weekly. A total of 211 ovulations were identified. Cyclicity was classified as normal in 60% of cows (38/63). Calculated over the operating period of all the devices (179 periods of estrus), the sensitivities and positive predictive values were, respectively, 71% and 71% for PM, 62% and 84% for AM1, 61% and 67% for the first algorithm of AM2, and 62% and 87% for the second algorithm of AM2. Both activity meters had a lower sensitivity but a higher positive predictive value than the PM (P < 0.05). For all devices, the performance in estrus detection was much poorer at the first postpartum ovulation than at subsequent ovulations (P < 0.05). Lactation rank and milk production affected some devices (P < 0.05). These devices could be used to reinforce visual observations, especially after 50 days postpartum, the minimum recommended delay to insemination. However, their full benefit remains to be verified in different farming systems and taking into account the specific objectives of the dairy farmer.

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.

Sire effect on early and late embryonic death in French Holstein cattle

We investigated the effect of maternal sire on early pregnancy failure (between D0, day of insemination and D90) in their progeny during the first and second lactations (n=3508) in the Holstein breed. The estimated breeding value (EBV) for cow fertility of 12 bulls (reliability⩾0.95) was used to create the following three groups: low, medium and high EBV (EBV from -0.7 to 1 expressed as genetic standard deviation relative to the mean of the breed). In their daughters (93 to 516 per bull), progesterone measurement was carried out on the day of artificial insemination (AI; D0) to check whether the cows were in the follicular phase and on D18 to 25 to assess non-fertilisation-early embryonic mortality (NF-EEM). Late embryonic mortality (LEM) and early foetal death (FD) were determined by ultrasonography on D45 and D90 and by the return to oestrus after the first AI. Frequencies of NF-EEM, LEM, FD and pregnancy were 33.3%, 11.7%, 1.4% and 48.5% and incidences were 35.1, 19.0, 2.7 and 51.1, respectively. Sire EBV was significantly related to the incidences of pregnancy failure between D0 and D90, fertilisation failure-early embryonic mortality (FF-EEM) and LEM but not to the incidence of FD between D45 and D90 of pregnancy. The relative risk (RR) of FF-EEM was significantly higher (RR=1.2; P<0.05) for the progeny group of low EBV bulls when compared with high EBV bulls. The same effect was observed when comparing LEM of the progeny groups from the low EBV bulls to those from moderate and high EBV bulls (RR, respectively, of 1.3 and 1.4; P<005). The incidence of FF-EEM was significantly higher when cows were inseminated before 80 days postpartum compared with later, and for the extreme values of the difference between milk fat and protein content measured during the first 3 months of lactation. FF-EEM was also significantly related to the year of observation. The incidence of LEM was higher for the highest producing cows and was influenced by interaction between milk yield×lactation rank and milk yield×milk protein content. In conclusion, this study showed large differences in early pregnancy failure between progeny groups and highlights the interest of accurate characterisation of embryonic death in order to identify potential candidate genes for female fertility.

Metabolomic profiling of bovine oviductal fluid across the oestrous cycle using proton nuclear magnetic resonance spectroscopy

In the present study we tested whether regulation of the metabolome in bovine oviductal fluid depended on the stage of the oestrous cycle, the side relative to ovulation and local concentrations of steroid hormones. Luminal fluid samples from both oviducts were collected in the preovulatory, postovulatory, mid- and late luteal phases, from cyclic cows at a local abattoir (18-27 cows per stage and side). The metabolomes were assessed by proton nuclear magnetic resonance spectroscopy (H-NMR). In all, 39 metabolites were identified, among which the amino acid glycine and the energy substrates lactate and myoinositol were the most abundant at all stages. The concentrations of 14 metabolites varied according to the stage of the oestrous cycle in at least one side relative to ovulation, of which four (choline, glucose-1-phosphate, glycine and pyruvate) were correlated with intraoviductal progesterone or oestradiol concentrations. Glucose-1-phosphate was most affected by the stage of the cycle, with four- to sixfold higher levels in luteal than periovulatory stages. These results provide new knowledge on the regulation of secretory activity in the oviduct and may help optimise culture media for gamete maturation, IVF and embryo production.