Effect of GnRH or Estradiol Benzoate on Reproductive Traits during a Heatsynch Protocol in Dairy Cows

Background: Milk production of cows is closely correlated with its reproductive efficiency. One of the several factors influencing the dairy efficiency is the decline in fertility of the cows/heifers. Use of hormonal protocol are often used to improve the fertility of the recipients. Several programs are available to inseminate dairy cows, with variation in the use of different types of hormones, time of use and range of duration period, as well as the time of AI. The objective of this study was to evaluate the efficiency of follicular wave emergence induction of estradiol benzoate in comparison to GnRH in a Heatsynch protocol and its influence on reproductive parameters.Materials, Methods & Results: In this study were used primiparous and multiparous Holstein cows (n = 325). Animals were divided randomly into two different treatments according with the hormone used to induce follicular wave emergence (D0). The GnRH group (n = 167), was given 25 mg, while in the EB group (n = 158) was used 2 mg. At same day, were inserted, a controlled internal drug-releasing containing 1.9 g of progesterone CIDR®. On day 7, CIDR was removed and cows were given 25 mg luteinizing hormone followed by an injection of 1 mg Inducer Ovulation at day 8. Cows were then observed for signs of estrus for at least two hours (twice daily at 7 am and 6 pm) for three days following CIDR® removal. Cows detected in estrus were inseminated 12 h later the estrus detection. Pregnancy status was determined by ultrasonography at 30 ± 5 d and 60 ± 5 d after AI. A single technician was responsible for the estrus detection and inseminations. A single technician was responsible for the estrus detection and inseminations. Ultrassonographic examinations with ultrasound, transrectal linear probe of 5 MHz, were performed for the diagnosis of pregnancy at 30 and 60 days after artificial insemination. Binomially distributed data, such as, estrous response, conception rate, pregnancy rate and pregnancy losses, were analyzed by Chi-square test. Pregnancy rates at 30-35 days and 60-65 days as well as pregnancy losses were considered in the model for the effect of parity (primiparous vs. multiparous) and the group of estrus behavior during the Heatsynch protocol. Conception rate was similar between GnRH (36.1%, 57/158) and EB (37.7%, 63/167) treatments. Cows showing estrus signs after CIDR removed were 71.9% in GnRH and 62% in EB group (P = 0.05). Embryonic losses were different (P = 0.03) according to groups of cows showing estrus signals or not.Discussion: Our results demonstrate that conception rates are not affected by using either EB or GnRH at the beginning of the Heatsynch protocol. Therefore, the EB can be an alternative choice to GnRH at Heatsynch beginning. Similar results were found by autor in dairy cows, once it was also observed that there is no difference in conception rate in two TAI protocols using either GnRH or EB. In Heatsynch protocols the increase in estrus detection are a key factor to increase fertility in lactating dairy cows. It can be explained once animals in regular estrous cycle have a palpable corpus luteum and circulating progesterone concentration higher than 1 ng/mL which leads than to enhance pregnancy ratios. The use of BE at the time of CIDR insertion in TAI protocols for dairy cattle proved to be an alternative to GnRH considering conception rates. Therefore, the use of BE at the time of CIDR insertion in a Heatsynch protocol in dairy cattle proved to be an alternative to GnRH which can be an important tool to increase the TAI utilization by farmers. Furthermore, in Heatsynch protocol cows showing estrus have pregnancy rates improved and lower pregnancy losses

Use of estradiol benzoate at the beginning of the heat synch protocol in lactating Holstein cows.

The aim of this study was to evaluate the use of estradiol benzoate inducing and synchronizing the follicular development in Holstein cows during a Heat Synch protocol. Two hundred and thirty primiparous (n= 110) and multiparous (n= 120) Holstein cows were enrolled in a Heat synch program consisting of a CIDR containing 1.9 g of progesterone, either a new one or previously used once (7d use), plus either 25 µg GnRH i.m or 2mg estradiol benzoate (EB) injection on day 0 (82 + 6 DIM) and all cows were given 25 mg PGF2α i.m upon CIDR removal seven days later (day 7) followed by an injection of 1 mg of estradiol cypionate (ECP) i.m at day 8. Used CIDRs had been thoroughly rinsed with a mild disinfectant solution, air-dried, and stored in a dry, enclosed container after first use. Cows were then observed for signs of estrus (twice daily at 7:00 and 18:00) for three days following CIDR removal. Cows observed in estrus were inseminated 12 h later. The fixed factors analyzed were the hormone used to the follicular wave induction at the be ginning of Heat Synch protocol, GnRH (n = 120) and estradiol benzoate (EB) (n = 110), and the CIDR uses (either a new one, second or third use). A single technician was responsible for the estrus detection and insemi nations. Pregnancy status was determined by ultrasonography at 30 to 35 d. Data were analyzed by the LOGISTIC procedure of SAS. Conception rate did not differ (P =0.86) between hormone groups GnRH and EB. In addition there was no difference (P = 0.18) in estrus signs between hormones treatments, as well as between primiparous and multiparous cows (P = 0.23). The CIDR uses did not differ (P = 0.75) in conception rate. Also there was no interaction (P>0.05) between CIDR uses and hormones treatments. In conclusion, EB may be used to induce and synchronize the follicular wave at beginning of Heat Synch protocol in dairy cows, as well as conception rates are not affected by CIDR uses.Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul - FAPERGSO objetivo deste estudo foi avaliar o uso do benzoato de estradiol na indução e sincronização do desenvolvimento folicular em vacas da raça Holandesa durante um protocolo Heat Synch. Foram incluídos no protocolo Heat synch duzentos e trinta vacas da raça Holandesa entre primíparas (n= 110) e multíparas (n= 120) consistindo de um CIDR contendo 1,9 g de progesterona, novo ou usado anteriormente uma vez (7d uso), mais 25 mg de GnRH intramuscular (IM) ou injeção de 2mg de benzoato de estradiol (BE) no dia 0 (82 + 6 DEL) e todas as vacas receberam 25mg de PGF2a IM durante a remoção do CIDR, sete dias depois (dia 7), seguido de uma injeção de 1mg de cipionato de estradiol (ECP) IM no dia 8 CIDRs usados foram cuidadosamente lavados com uma solução desinfetante suave, secas ao ar e armazenadas em um recipiente seco, fechado após a primeira utilização. Os animais foram então observados para sinais de cio (duas vezes ao dia, às 7:00 e 18:00 ) por três dias após a retirada do CIDR . Vacas observadas em cio foram inseminadas 12 horas depois. Os elementos fixos analisados foram utilizados para o hormônio na indução da onda o folicular, no início do protocolo Heat Synch, GnRH (n = 120) e de benzoato de estradiol (BE) (n = 110 ) , e utilização do CIDR (novo, de segundo ou terceiro uso ) . Um único técnico foi responsável pela detecção de cio e inseminações. O diagnóstico de gestação foi determinado por ultrassonografia aos 30 a 35 d. Os dados foram analisados pelo procedimento LOGISTIC do SAS. A taxa de concepção não diferiu (P= 0,86) entre os grupos hormônio GnRH e BE. Além disso, não houve diferença (P= 0,18) em sinais de cio entre tratamentos com hormônios, bem como entre vacas primíparas e multíparas (P = 0,23). Os usos de CIDR não diferiu (P = 0,75) na taxa de concepção. Também não houve interação (P> 0,05) e ntre os usos de CIDR e tratamentos de hormônios. Em conclusão, o BE pode ser usado para induzir e sincronizar a onda folicular no início do protocolo Heat Synch em vacas leiteiras, bem como as taxas de concepção não são afetadas pelo uso de CIDR

Light intensity on growth, leaf micromorphology and essential oil production of Ocimum gratissimum

Light conditions can promote the growth and development of plants and contribute to increase the essential oil production of commercially cultivated medicinal and aromatic species. In view of the great importance of Ocimum gratissimum L., Lamiaceae, as an aromatic plant, the objective of this work was to determine the effect of light intensities (approximately 4, 7, 11 and 20 mol m-2 d-1) on growth, foliar micromorphology, essential oil content, yield and chemical composition of O. gratissimum. Biomass production of different organs, root:shoot ratio and leaf mass per area were found to linearly increase with increased light availability, whereas stem dry matter fraction, number of leaves, leaf area and plant height have increased up to 10 mol m-2 d-1 and decreased from this value. The tector trichomes density increased with increased light availability, but there was no effect of light treatments on the glandular trichomes density and essential oil content. Regardless of the light level, the major component of the essential oil was eugenol. The essential oil yield per plant increased linearly with light intensity as a direct effect of increased leaf biomass under similar conditions