1,721,471 research outputs found
Insulin like growth factor-I in heat stressed bovine oocytes: effect on embryo development
No full textThe aim of the present study was to investigate the effects of insulin like growth factor-I (IGF-I) during in vitro maturation of bovine oocytes under heat stress (HS) on subsequent cleavage rate (CR) at 45 hours post insemination (hpi), blastocyst rate (BR) at 168 hpi and apoptotic cell ratio (ACR) after active caspase staining at both time points. Selected oocytes were assigned to four maturation groups in serum-free media supplemented with EGF (20 ng/ml) as follows, two control groups: control (maturation temperature 38.5°C for 22h) or HS-control (maturation temperature 40.5°C for 12h followed by 38.5°C for 10h) and two treatment groups with the addition of IGF-I (100 ng/ml); IGF-I (maturation temperature 38.5°C) or HS-IGF-I (maturation temperature 40.5°C for 12h followed by 38.5°C for 10h). Matured oocytes were fertilized and cultured in SOF medium supplemented with 5 % FCS. Half of the cultured zygotes were checked at 45 hpi for their CR and ACR, while the other half was checked at 168 hpi for determining BR and ACR. General linear models (CR and BR) or logistic models (ACR) were used to analyze the data. The results of CR were 82.8±1a, 53.1±1.5bc, 73.9±1.1ab and 45.5±1.8c % and the BR were 31.7±5.8a, 10.2±1.6b, 26.4±4.8a and 11.9±2.2b %, in IGF-I, HS-IGF-I, control and HS-control groups, respectively (a,b,c P<0.05). The results of ACR at 45 hpi were 16.5±2.2a, 17±4.2a, 19.7±3.8 a and 23.2±4.6b % and ACR results at 168 hpi were 3.1±0.8a, 7.8±2.1bc, 5±0.6b and 7±2.1c %, for the IGF-I, HS-IGF-I, control and HS-control groups, respectively (a,b,c P<0.05). It can be concluded that HS reduced both CR and BR and increased ACR either at 45 or 168 hpi. Addition of IGF-I during maturation under HS conditions rescued cleaved zygotes from apoptosis and tended to improve CR (P=0.06), however, no beneficial effects could be detected at 168 hpi either on BR or ACR, which may indicate that IGF-I added during maturation under HS could rescue preimplantation embryos in early stages of development but this effect was not preserved after embryonic genome activation
Prenatal environment impacts telomere length in newborn dairy heifers
No full textTelomere length is associated with longevity and survival in multiple species. In human population-based studies, multiple prenatal factors have been described to be associated with a newborn's telomere length. In the present study, we measured relative leukocyte telomere length in 210 Holstein Friesian heifers, within the first ten days of life. The dam's age, parity, and milk production parameters, as well as environmental factors during gestation were assessed for their potential effect on telomere length. We found that for both primi- and multiparous dams, the telomere length was 1.16% shorter for each day increase in the calf's age at sampling (P = 0.017). The dam's age at parturition (P = 0.045), and the median temperature-humidity index (THI) during the third trimester of gestation (P = 0.006) were also negatively associated with the calves' TL. Investigating multiparous dams separately, only the calf's age at sampling was significantly and negatively associated with the calves' TL (P = 0.025). Results of the present study support the hypothesis that in cattle, early life telomere length is influenced by prenatal factors. Furthermore, the results suggest that selecting heifers born in winter out of young dams might contribute to increased longevity in dairy cattle
The influence of peripartal feeding scheme and body condition on sow reproductive and conditional performance
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2D vision based measuring device for teat morphology in dairy cows
Full text linkTeat morphology is an important parameter in choosing the most appropriate teatcup liner for a herd since the interaction between teat and liner can strongly affect the milking characteristics and udder health. Nevertheless, information on teat morphology is very scarce and rarely sufficient for liner selection. Gathering information on large scale with current techniques is time consuming, subjective and not always accurate. However, the ability to measure teat parameters in an easy way and on large scale has many applications. This study presents a new vision based measuring technique for teat shape parameters. A camera is used to obtain a 2D image of the teat and image processing analyses to determine teat length and diameters. In addition, shape parameters of teat and teat end can be defined. The resolution in length and diameters is better than 0.5 mm. The error on the length of the teats that make an angle in the longitudinal plane of maximum 25° towards the camera, is no more than 5 %. To validate the repeatability of the measuring method, the teats of one Holstein cow were measured 5 times by 8 different members of a test panel of which 5 people were experienced in working with cows. Reproducibility was tested by measuring the teats of 7 Holstein cows by the same test panel. The teats of each cow were measured once in a defined order. The sequence in which the members measured the teats was randomized. No significant differences were found between the 5 successive measurements of one person on 3 teats. Significant differences in left-front teat measurements (p=0.002) were due to the lack of cow experience (p=0.022). Teat length measurements did not significantly differ between members of the test panel as long as teats could be easily reached. However, no significant differences were found for all teats between operators familiar with cows. In conclusion, a new accurate, repeatable and reproducible method was developed to measure teat parameters in all kinds of milking parlours. To obtain repeatable and reproducible results, some training in working in close interaction with cows is advised
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The role of insulin in the energy conflict between milk production and ovarian activity during the transition period of high-yielding dairy cows
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