Naslov
Environmental heat stress alters lipid metabolism and antioxidant status and impairs reproduction in dairy cows

Autori
Turk, Romana ; Podpečan, Ožbalt ; Mrkun, Janko ; Flegar-Meštrić, Zlata ; Perkov, Sonja ; Zrimšek, Petra

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Proceedings of the XV. Middle European Buiatric Congress, 10th Symposium of the ECBHM, 25th Conference of the Slovenian Buiatric Association, Maribor 10-13 June 2015 / - , 2015, 100-100

Skup
XV. Middle European Buiatric Congress, 10th Symposium of the ECBHM, 25th Conference of the Slovenian Buiatric Association, Maribor 10-13 June 2015

Mjesto i datum
Maribor, Slovenija, 10.06.2015. - 13.06.2015

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
negative energy balance; oxidative stress; calving to conception interval

Sažetak
Introduction: Environmental heat stress compromises efficient animal production including reproductive performance in dairy cows. Negative effects of heat stress on reproduction are thought to be a consequence of poor appetite and reduced nutrient intake resulting in a negative energy balance (NEB), (Wolfenson et al., 2000). Lipid mobilisation during NEB and thus increased non- esterified fatty acids (NEFA) and NEFA-derived ketones provide a significant source of energy for transitioning dairy cows (Wheelock et al. 2010). Changes in energy metabolism, especially an increased NEFA oxidation in the liver are associated with increased production of reactive oxygen species (ROS) and oxidative stress (Turk et al., 2013). Decreased feed intake and NEB during heat stress negatively influence plasma insulin and IGF-I resulting in a poor follicular development, low oestrus expression and poor quality of oocytes with a consequence of impaired reproduction (Wolfenson et al., 2002). The aim of this study was to investigate effects of seasonal thermal stress on lipid metabolism, antioxidant activity and reproductive performance in dairy cows. Materials and methods: Thirty two healthy Holstein-Frisian dairy heifers were included in the study. Animals were divided into two groups according to the ambient temperature ; winter (N=14) and summer season (N=18). Paraoxonase 1 (PON1) activity, total antioxidant status (TAS), lipid status, NEFA and BHB were measured by spectrometric methods on the automated analyzers at the time of insemination (baseline value) and from -1 until +8 weeks relative to calving. Reproduction parameters, i.e. number of services per conception and calving to conception (CC) interval, were recorded from the first successful insemination of heifers until their successful insemination after the first calving (primiparous cows). Results and discussion: In primiparous cows, a significant higher number of services per conception were needed in summer than in winter (P<0.05), whereas no difference was observed in the number of services per conception in heifers between summer and winter. In addition, the CC interval in primiparous cows was longer in summer than in winter. NEFA concentration was significantly higher in summer than in winter from 2 to 8 weeks postpartum (P<0.05). Consequently, increased BHB concentration was observed in summer from 2 to 4 weeks after calving (P<0.05). TAS concentration was significantly lower in summer from 1week before calving until 8 weeks after calving compared to the winter group (P<0.05). PON1 was significantly decreased 1 week prior to parturition and was continuously increasing up to 8 weeks of lactation in both seasons. However, in summer PON1 remained decreased compared to the baseline value (P<0.05). These results indicated an increased lipid mobilization and lower antioxidant status in summer compared to winter. The CC interval significantly positively correlated with NEFA and BHB in summer indicating that poor reproductive performance significantly correlated with the degree of NEB. A significant negative correlation of CC interval with PON1 and TAS were found in summer and winter respectively, indicating that lower antioxidant status contributes to a longer CC interval. Reproductive performance significantly negatively correlated with the severity of NEB suggesting that lipid mobilisation and lower antioxidant status might contribute to poor reproduction ability in dairy cows during hot months.

Izvorni jezik
Engleski

POVEZANOST RADA