Under ideal conditions (i.e., with donor, recipient, fertile stallions, and trained personnel), 70% to 85% recovery rates and 75% to 85% pregnancy rates can be expected, resulting in overall ET efficiency of 45% to 65%. Both rates are lower (20% to 45%) in older subfertile mares and subfertile stallions. This is why weekly or monthly analysis of records must be performed and categorized by donor age, stallion, and month.
Acknowledgments: The presented work is part of the research done in scientific projects
„TR-31084“ and „III-46005“ granted by the Serbian Ministry of Education and Science.
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Original scientific paper UDC: 637.1:636.082.4
THE EFFECT OF PROGESTERONE MONITORING IN IMPROVING REPRODUCTIVE EFFICIENCY IN FIRST LACTATING DAIRY COWS
Milovanović A.
1, Barna T.
1, Apić J.
1, Kujača V.
2, Lazarević M.
3, Gvozdić D.
3, Maksimović N.
4Abstract: The aim of this study was to determine the impact of the level of progesterone in
the cycle preceding insemination, as well as the ability to shorten the open days period of primiparous cows which were under the control of progesterone (P group - 43 cows), compared to the control group of primiparous cows that was not under progesterone supervision (C group – 62 cows). Progesterone concentration was determined in the whole milk by EIA test.
The concentration of progesterone in the diestrus preceding the first insemination was significantly higher for the cows that become pregnant, in relation to the non-pregnant cows (6.70±2.77 ng/m to 3.60±1.92 ng/ml; p> 0.01). Values for the concentration of progesterone ≥5ng/ml in the above period provided a very high probability of conception (80%).
Time to first insemination in the group P was reduced by 10.56 days (83.03 vs. 93.59 days), and the number of inseminations decreased by 0.24 (1.14 vs. 1.38), but no statistical significance was observed. Statistical significance was determined for shortening of the open days period by 25.06 days in the P group (80.46 vs. 105.52 days, p=0.024).
Progesterone test can be used as a reliable tool in the control of sexual cycle, for better understanding of the physiological significance of different concentrations of progesterone in the conception as well as in the improvement of reproductive parameters in high productive animals.
Keywords: cows, reproduction, progesterone test, milk
4Maksimovenior Specialist Adviser; Institute for
Introduction
Over the last 25 years, there has been significant progress in the selection of cows to increase milk production. However, for that reason, the reproduction was neglected, which resulted in a decline in reproductive efficiency in dairy cows (Moore and Thatcher, 2006).
Progesterone (P4) is a steroid hormone which is secreted by the corpus luteum after ovulation in the luteal phase of the sexual cycle. It is essential for the preservation of
1Milovanović Aleksandar, PhD, Senior Specialist Adviser; Barna Tomislav, DVM-spec., Specialist Adviser; Apić Jelena, DVM, Research Assistant, Scientific veterinary institute ''Novi Sad'', Novi Sad, Serbia
2 Kujača Velibor, DVM, d.o.o. „Veterina“ Pik Bečej
3 Lazarević Miodrag, PhD, professor; Gvozdić Dragan, PhD, professor, University of Belgrade, Faculty of veterinary medicine, Belgrade, Serbia
Corresponding author: Milovanović Aleksandar, email: aca@niv.ns.ac.rs
09-11.09.2015. Novi Sad, Serbia
_______________________________________________________________________
pregnancy and luteal deficiency is considered a common cause of infertility (Parkinson, 2001).
Progesterone concentration in the blood is result of a balance between production and metabolism (Wiltbank et al., 2014; Sangsritavong et al., 2002). Opsomer et al. (1999) pointed out that the concentration of plasma progesterone in cows indicates secretory activity of luteal tissue, as there are no other significant sources of progesterone.
Intensive selection of cows for high milk production has encouraged the need for large amounts of dry matter in the diet of cows and more intensive metabolism of nutrients, leading to a reduction of progesterone concentration in the circulation due to an accelerated catabolism of steroids (Staples et al., 1990; Hommeida et al. 2004). The key factor in the elimination of P4 is the intensity of metabolism in the liver, i.e., the concentration of P4 is directly dependent on the blood flow through the liver (Wiltbank et al., 2006). For instance, when blood flow through the liver increases from 1.000 to 2.000 L/hour, the concentration of P4 in the blood decreases by 50%, regardless of the fact that there was no change in the intensity of production P4 or changes in the liver enzymes concentration responsible for the elimination of P4.
The control of fertility of cows and heifers using the EIA test (Enzyme Immuno Assay) for direct measurement of progesterone concentration in the whole milk and blood serum is a very sensitive and practical way of monitoring the reproduction in cows.
Routine control of cow fertility in this way is a privilege of very few developed countries, because of the difficulties in producing EIA test components of sufficient specificity and sensitivity.
In the Laboratory for reproduction of the Veterinary Research Institute "Novi Sad", progesterone test results were used to detect the quality of oestrus, proper time of insemination and ovarian hypofunction (Barna, 2010; Barna et al., 2013). Thus, for example, on our farms, based on the progesterone test, the wrong time of insemination was observed in 22.86% of cows (16/70). Nebel et al. (1987) reported that detection of estrus was a problem in 30% of the herds studied, with up to 46% of the cows inseminated when milk progesterone concentration was high.
Maintaining high milk production requires a modern approach to recording,
monitoring and processing parameters of reproductive efficiency, both in individual
animals and at the level of the herd, in order for the progesterone test to have the full use
value. Good recording plays a key role in the control of reproduction on dairy farms. The
oestrus detection, optimal moment of insemination and early diagnosis of pregnancy are
the basic problems of modern breeding of dairy cows (Milovanović et al., 2011).
No documento
19th INTERNATIONAL CONGRESS ON BIOTECHNOLOGY IN ANIMAL REPRODUCTION (ICBAR)
(páginas 42-45)