Is bovine somatotropin an alternative strategy to overcome the detrimental effects of high-gain diets on prepubertal Holstein × Gyr heifers?

Feeding high-gain diets and an inadequate energy and protein ratio during pre-puberty may lead to impaired growth and mammary gland development of heifers. Thus, frequent application of bovine somatotropin (bST) may prevent future losses in productivity, improve mammary development and animal performance. We aimed to evaluate the effects of bST on digestibility, performance, blood metabolites, mammary gland development, and carcass composition of high-performance prepubertal Holstein × Gyr heifers. Thirty-four Holstein × Gyr heifers with an average initial body weight of 218 ± 49 kg and 14 ± 4 months of age were submitted to an 84-day trial evaluating the effects of no bST or bST injections. Treatments were randomly assigned to each animal within one of the tree blocks. The bST did not influence digestibility or performance parameters. Regarding blood results, IGF1 concentration presented an interaction between treatment and day, where bST heifers had the highest IGF1 concentration. Heifers receiving bST also showed increased ribeye area; however, only an experimental day effect for backfat thickness was observed, with greater accumulation of carcass fat on day 84. Heifers receiving bST had lower pixels/mm² on parenchyma, characteristic of greater parenchymal tissue. Moreover, heifers on bST treatment also had reduced pixels/mm2, characteristic of reduced fat pad tissue. Lastly, bST injections did not influence liver and muscle gene expression, nor most genes evaluated in mammary gland tissue, except for IGFBP3 expression, which was greater for bST heifers. In summary, we confirm the efficacy of bST injections to overcome the detrimental effects of high-gain diets on mammary gland growth and to improve lean carcass gain of prepubertal Holstein × Gyr heifers.

Effect of protein supplement level on the productive and reproductive parameters of replacement heifers managed in intensive grazing systems.

Evaluations of replacement heifers in intensively managed grazing systems in tropical conditions are warranted. Thus, we aimed to evaluate performance, muscle and mammary gland development, oocyte quality, and in vitro production of embryos of crossbred heifers grazing an intensively managed pasture and supplemented with high or low protein concentrates. Eighteen pubertal crossbred heifers (Holstein x Gyr) with an initial weight of 350 ± 8.0 kg were used in a 60-day trial. Two supplement types, 12% crude protein (CP) (S12CP) or 24% CP (S24CP), and a control treatment (mineral mixture, CON) were randomly distributed to the heifers. Throughout the experiment, four digestibility trials were performed over four consecutive days. Four ovarium pick-ups were performed to evaluate oocyte quality and in vitro embryo production. Lastly, ultrasounds of carcasses and mammary glands were performed. The intakes of dry matter (DM), digestible energy (DE), and CP were greater for supplemented (SUP) compared with CON heifers. The SUP heifers had a greater average daily gain (ADG) (645 versus 390 g/d) and rib eye area (58.78 versus 53.32 cm2) than the CON heifers. Oocyte recovery, quality, and follicle features were not affected by supplementation strategy. However, the cleavage rate (47.17% versus 30.31%) and blastocyst rate (27.91% versus 10.12%) were negatively affected by supplementation. The S12CP presented a blastocyst rate much lower than the S24CP (3.02% versus 17.23%). Carcass ultrasonography indicated a trend for greater rib eye area for S24CP and mammary ultrasonography indicated no effects of supplementation on mammary gland development. In summary, supplementation seems to be an appropriate strategy for satisfactory performance, with greater muscle deposition and no negative impacts on mammary gland development. However, in vitro embryo production was impaired when the animals received the supplementation with 12% CP.

Natural infection in ovarian structures by bovine herpesvirus 1: molecular and serological detection / Infecção natural em estruturas ovarianas pelo Herpesvírus bovino 1: detecção molecular e sorológica

In this study, the polymerase chain reaction (PCR) was used to evaluate the presence of viral DNA in ovarian tissue, in the cumulus-oocyte complex (COC), follicular liquid, and blood of animals naturally infected with bovine herpesvirus-1 (BoHV-1). The serum profile of the sampled animals was also evaluated. Samples of serum, blood, ovarian tissue, follicular liquid, and COC were collected from 147 slaughterhouse animals that were not vaccinated against BoHV-1. Contaminated or insufficient samples were disregarded. Serological tests allowed the identification of serum-positive animals with neutralizing antibodies against BoHV-1. Analysis of samples by PCR revealed the presence of viral DNA in 0.9% (1/115) of the COC samples, in 4.3% (5/117) of the ovarian tissue samples, and in 2.8% (3/108) of the blood samples. Viral DNA was not detected in any of the follicular liquid samples. In serological samples, a positivity of 83.6% (117/140) was observed for BoHV-1. All PCR-positive animals, regardless of the samples analyzed, showed positivity in the serum neutralization test for the detection of BoHV-1-specific antibodies. According to these results, a high prevalence of antibodies against BoHV-1 was detected in naturally infected animals from different herds, and the molecular tests revealed the presence of viral DNA in bovine ovarian tissue, providing evidence that this might be...(AU)

Neste trabalho foi avaliada a presença do DNA viral, por meio da Reação em Cadeia da Polimerase (PCR), no tecido ovariano, nos oócitos, líquido folicular e sangue de vacas naturalmente infectadas. Também foi avaliado o perfil sorológico dos animais amostrados. Foram coletadas amostras de soro, sangue, tecido ovariano, líquido folicular e complexo cumulus-oócitos de 147 animais abatidos em frigorífico não vacinados contra o herpesvirus bovino 1 (BoHV-1). Amostras tóxicas ou insuficientes foram descartadas. Os testes sorológicos foram realizados permitindo a identificação dos animais soropositivos para anticorpos neutralizantes contra o BoHV-1. Foram realizadas as PCRs onde foi observada a presença do DNA viral em 0,9% (1/115) dos oócitos, em 4,3% (5/117) do tecido ovariano e em 2,8% (3/108) do sangue. Em nenhuma das amostras de líquido folicular foi detectado o DNA viral. Nas amostras sorológicas observou-se 83,6% (117/140) de positividade para o BoHV-1. Dentre os animais positivos na PCR, independente das amostras, todos apresentavam positividade no teste de soroneutralização para detecção de anticorpos para BoHV-1. Conclui-se que em animais de diferentes rebanhos analisados foi detectada alta prevalência de anticorpos contra o BoHV-1 e que nos testes moleculares houve a presença do DNA viral em amostras de tecidos ovarianos de bovinos, evidenciando que estas estruturas poderia...(AU)

Natural infection in ovarian structures by bovine herpesvirus 1: molecular and serological detection / Infecção natural em estruturas ovarianas pelo Herpesvírus bovino 1: detecção molecular e sorológica

In this study, the polymerase chain reaction (PCR) was used to evaluate the presence of viral DNA in ovarian tissue, in the cumulus-oocyte complex (COC), follicular liquid, and blood of animals naturally infected with bovine herpesvirus-1 (BoHV-1). The serum profile of the sampled animals was also evaluated. Samples of serum, blood, ovarian tissue, follicular liquid, and COC were collected from 147 slaughterhouse animals that were not vaccinated against BoHV-1. Contaminated or insufficient samples were disregarded. Serological tests allowed the identification of serum-positive animals with neutralizing antibodies against BoHV-1. Analysis of samples by PCR revealed the presence of viral DNA in 0.9% (1/115) of the COC samples, in 4.3% (5/117) of the ovarian tissue samples, and in 2.8% (3/108) of the blood samples. Viral DNA was not detected in any of the follicular liquid samples. In serological samples, a positivity of 83.6% (117/140) was observed for BoHV-1. All PCR-positive animals, regardless of the samples analyzed, showed positivity in the serum neutralization test for the detection of BoHV-1-specific antibodies. According to these results, a high prevalence of antibodies against BoHV-1 was detected in naturally infected animals from different herds, and the molecular tests revealed the presence of viral DNA in bovine ovarian tissue, providing evidence that this might be...

Neste trabalho foi avaliada a presença do DNA viral, por meio da Reação em Cadeia da Polimerase (PCR), no tecido ovariano, nos oócitos, líquido folicular e sangue de vacas naturalmente infectadas. Também foi avaliado o perfil sorológico dos animais amostrados. Foram coletadas amostras de soro, sangue, tecido ovariano, líquido folicular e complexo cumulus-oócitos de 147 animais abatidos em frigorífico não vacinados contra o herpesvirus bovino 1 (BoHV-1). Amostras tóxicas ou insuficientes foram descartadas. Os testes sorológicos foram realizados permitindo a identificação dos animais soropositivos para anticorpos neutralizantes contra o BoHV-1. Foram realizadas as PCRs onde foi observada a presença do DNA viral em 0,9% (1/115) dos oócitos, em 4,3% (5/117) do tecido ovariano e em 2,8% (3/108) do sangue. Em nenhuma das amostras de líquido folicular foi detectado o DNA viral. Nas amostras sorológicas observou-se 83,6% (117/140) de positividade para o BoHV-1. Dentre os animais positivos na PCR, independente das amostras, todos apresentavam positividade no teste de soroneutralização para detecção de anticorpos para BoHV-1. Conclui-se que em animais de diferentes rebanhos analisados foi detectada alta prevalência de anticorpos contra o BoHV-1 e que nos testes moleculares houve a presença do DNA viral em amostras de tecidos ovarianos de bovinos, evidenciando que estas estruturas poderia...

USE OF rbST ON ESTRUS DAY IN RECIPIENTS OF FROZEN BOVINE EMBRYOS / USO DA rbST NO DIA DO ESTRO EM RECEPTORAS DE EMBRIÃO BOVINO CRIOPRESERVADO

The aim of this study was to evaluate the effects of the administration of 250 and 500 mg of rbST to bovine recipients of frozen embryos on estrus day on pregnancy rate and on serum progesterone concentration.  In experiment I, 44 recipients were allotted into two treatments: T1(n = 22, control) and T2(n = 22), in which animals received 250 mg rbST subcutaneously.  In experiment II, 71 recipients were allotted in: T1(n = 31, control) and T2(n = 40), in which animals received 500 mg rbST. Pregnancy diagnosis occurred 30 days after estrus. Pregnancy rates did not differ between treatments in both experiments: 40.9%(T1) vs 50.0%(T2) and 48.4%(T1) vs 52.5%(T2) in experiments I and II, respectively. Likewise, the average progesterone concentration (ng/mL plasma) obtained from blood collection samples on the embryo transfer day did not show differences between the treatments: 5.29 ± 0.62(T1) vs. 5.77 ± 0.48(T2) and 4.94 ± 0.54(T1) vs. 4.77 ± 0.51(T2) in experiments I and II, respectively. These results demonstrate that the administration of 250 or 500 mg rbST on estrus day does not increase pregnancy rate nor the serum progesterone concentration of frozen bovine embryo recipients.KEYWORDS: bovine; embryo recipients; pregnancy rate.

Estudou-se o efeito da administração de duas doses de rbST (250 e 500 mg) no dia do estro em receptoras de embrião bovino criopreservado na taxa de gestação e na concentração sérica de progesterona. No experimento I, 44 receptoras foram distribuídas em dois tratamentos: T1(n = 22, controle) e T2(n = 22), recebendo a administração subcutânea de 250 mg de rbST. No experimento II, 71 receptoras foram distribuídas em: T1(n = 31, controle) e T2(n = 40), recebendo 500 mg de rbST. Os diagnósticos de gestação foram realizados 30 dias após o estro. As taxas de gestação não diferiram entre tratamentos em ambos os experimentos (40,9%(T1) vs 50,0%(T2) e 48,4%(T1) vs 52,5%(T2) para os experimentos I e II, respectivamente). As concentrações séricas de progesterona (ng/mL de plasma), obtidas nas amostras de sangue coletadas no dia da inovulação, não diferiram entre tratamentos, sendo 5,92 ± 0,62(T1) vs 5,77 ± 0,48(T2) e 4,94 ± 0,54(T1) vs 4,77 ± 0,51(T2) para os experimentos I e II, respectivamente. Esses resultados indicam que a administração de 250 ou 500 mg de rbST, no dia do estro, não proporciona incremento tanto na taxa de gestação como na concentração sérica de progesterona de receptoras de embrião bovino criopreservado.PALAVRAS-CHAVE: bovino; receptora de embrião; taxa de gestação.

USE OF rbST ON ESTRUS DAY IN RECIPIENTS OF FROZEN BOVINE EMBRYOS / USO DA rbST NO DIA DO ESTRO EM RECEPTORAS DE EMBRIÃO BOVINO CRIOPRESERVADO

The aim of this study was to evaluate the effects of the administration of 250 and 500 mg of rbST to bovine recipients of frozen embryos on estrus day on pregnancy rate and on serum progesterone concentration.  In experiment I, 44 recipients were allotted into two treatments: T1(n = 22, control) and T2(n = 22), in which animals received 250 mg rbST subcutaneously.  In experiment II, 71 recipients were allotted in: T1(n = 31, control) and T2(n = 40), in which animals received 500 mg rbST. Pregnancy diagnosis occurred 30 days after estrus. Pregnancy rates did not differ between treatments in both experiments: 40.9%(T1) vs 50.0%(T2) and 48.4%(T1) vs 52.5%(T2) in experiments I and II, respectively. Likewise, the average progesterone concentration (ng/mL plasma) obtained from blood collection samples on the embryo transfer day did not show differences between the treatments: 5.29 ± 0.62(T1) vs. 5.77 ± 0.48(T2) and 4.94 ± 0.54(T1) vs. 4.77 ± 0.51(T2) in experiments I and II, respectively. These results demonstrate that the administration of 250 or 500 mg rbST on estrus day does not increase pregnancy rate nor the serum progesterone concentration of frozen bovine embryo recipients.KEYWORDS: bovine; embryo recipients; pregnancy rate.

Estudou-se o efeito da administração de duas doses de rbST (250 e 500 mg) no dia do estro em receptoras de embrião bovino criopreservado na taxa de gestação e na concentração sérica de progesterona. No experimento I, 44 receptoras foram distribuídas em dois tratamentos: T1(n = 22, controle) e T2(n = 22), recebendo a administração subcutânea de 250 mg de rbST. No experimento II, 71 receptoras foram distribuídas em: T1(n = 31, controle) e T2(n = 40), recebendo 500 mg de rbST. Os diagnósticos de gestação foram realizados 30 dias após o estro. As taxas de gestação não diferiram entre tratamentos em ambos os experimentos (40,9%(T1) vs 50,0%(T2) e 48,4%(T1) vs 52,5%(T2) para os experimentos I e II, respectivamente). As concentrações séricas de progesterona (ng/mL de plasma), obtidas nas amostras de sangue coletadas no dia da inovulação, não diferiram entre tratamentos, sendo 5,92 ± 0,62(T1) vs 5,77 ± 0,48(T2) e 4,94 ± 0,54(T1) vs 4,77 ± 0,51(T2) para os experimentos I e II, respectivamente. Esses resultados indicam que a administração de 250 ou 500 mg de rbST, no dia do estro, não proporciona incremento tanto na taxa de gestação como na concentração sérica de progesterona de receptoras de embrião bovino criopreservado.PALAVRAS-CHAVE: bovino; receptora de embrião; taxa de gestação.