Effect of temperature – humidity index on the onset of post- partum ovarian activity and reproductive behavior in Bos indicus cows

The effect of climatic factors on ovarian activity and reproductive behavior (RB) was evaluated in 46 Bos indicus cows kept under grazing conditions. Temperature-humidity index (THI) was used as an indicator of stress and divided in alert, damage and emergency levels. Fat thickness (FAT) was taken during the last trimester of gestation (LTG) to approximately 90d postpartum (PP). At 30d PP animals received a progesterone (P4)-releasing device (CIDR) which was withdrawn 9d later. Ovarian activity was assessed by blood progesterone on days 21, 24, 27, 30, 49, 51, and 54 PP. Animals were divided into three groups, higher, and moderate RB and non-behavior. Sixty percent presented a THI >74 increasing dramatically from June to September up to >78. During LTG, animals lost 27% of their body reserves contrasting to PP where an increase of 2.6% (P=0.002) was observed. The percentages of cyclic and non-cyclic animals were 57 and 43%, respectively (P> 0.05). Seventy-two percent displayed RB and 28% were non-behavior (P<0.05). A negative correlation (r = -0.307; P = 0.038) between THI and RB, and a positive correlation (r = 0.427; P = 0.003) between the onset of ovarian activity and RB were observed. Differences in THI during the LTG (P<0.01) were observed between cyclic and non-cyclic animals. Non-behavior cows in the LTG had a higher THI (P <0.05). High levels of THI have a negative effect on the resumption of ovarian activity and RB in Bos indicus especially if high THI occurs during the last trimester of gestation.

Effect of temperature humidity index on the onset of post- partum ovarian activity and reproductive behavior in Bos indicus cows

The effect of climatic factors on ovarian activity and reproductive behavior (RB) was evaluated in 46 Bos indicus cows kept under grazing conditions. Temperature-humidity index (THI) was used as an indicator of stress and divided in alert, damage and emergency levels. Fat thickness (FAT) was taken during the last trimester of gestation (LTG) to approximately 90d postpartum (PP). At 30d PP animals received a progesterone (P4)-releasing device (CIDR) which was withdrawn 9d later. Ovarian activity was assessed by blood progesterone on days 21, 24, 27, 30, 49, 51, and 54 PP. Animals were divided into three groups, higher, and moderate RB and non-behavior. Sixty percent presented a THI >74 increasing dramatically from June to September up to >78. During LTG, animals lost 27% of their body reserves contrasting to PP where an increase of 2.6% (P=0.002) was observed. The percentages of cyclic and non-cyclic animals were 57 and 43%, respectively (P> 0.05). Seventy-two percent displayed RB and 28% were non-behavior (P<0.05). A negative correlation (r = -0.307; P = 0.038) between THI and RB, and a positive correlation (r = 0.427; P = 0.003) between the onset of ovarian activity and RB were observed. Differences in THI during the LTG (P<0.01) were observed between cyclic and non-cyclic animals. Non-behavior cows in the LTG had a higher THI (P <0.05). High levels of THI have a negative effect on the resumption of ovarian activity and RB in Bos indicus especially if high THI occurs during the last trimester of gestation.(AU)

Influence of male to female ratio on hormone profiles and reproductive performance of anestrus postpartum ewes subjected to the male effect

Background: Complete isolation of genders allows intense estrous induction and synchronization once rams are introduced in ewe flocks at the onset of the breeding season (BS). This management practice, defined as the male effect, results from a neuroendocrine process mediated by pheromones. The male effect is a straightforward procedure to induce estrous in noncycling ewes, but conditions for its use have not been fully explored. Thus, this study aimed to evaluate hormone levels and ovarian activity of postpartum ewes in anestrus which are subjected to the male effect under different male to female ratios. Material, Methods & Results: Pospartum females were selected according to body condition score and cyclicity status. Females were kept apart from males during 30 days at a distance of 10 m. Anestrus and ovulation were determined by P4 measures on days 10, 20 and 30 after isolation from males. After P4 concentration diagnosis, anestrus ewe (n = 99) were subjected to male to ewe ratios (MFR) of 1:20 (MFR20), 1:30 (MFR30) and 1:40 (MFR40). Santa Inês rams (n = 3) of proven fertility were used. Three females of each group were randomly subjected to blood collection for LH concentration analysis. Ovarian activity was performed by ultrasonography after estrus manifestation in six ewe of each group. Estrus events were observed twice a day during the BS of 35 days, and estrus [...](AU)

Influence of male to female ratio on hormone profiles and reproductive performance of anestrus postpartum ewes subjected to the male effect

Background: Complete isolation of genders allows intense estrous induction and synchronization once rams are introduced in ewe flocks at the onset of the breeding season (BS). This management practice, defined as the male effect, results from a neuroendocrine process mediated by pheromones. The male effect is a straightforward procedure to induce estrous in noncycling ewes, but conditions for its use have not been fully explored. Thus, this study aimed to evaluate hormone levels and ovarian activity of postpartum ewes in anestrus which are subjected to the male effect under different male to female ratios. Material, Methods & Results: Pospartum females were selected according to body condition score and cyclicity status. Females were kept apart from males during 30 days at a distance of 10 m. Anestrus and ovulation were determined by P4 measures on days 10, 20 and 30 after isolation from males. After P4 concentration diagnosis, anestrus ewe (n = 99) were subjected to male to ewe ratios (MFR) of 1:20 (MFR20), 1:30 (MFR30) and 1:40 (MFR40). Santa Inês rams (n = 3) of proven fertility were used. Three females of each group were randomly subjected to blood collection for LH concentration analysis. Ovarian activity was performed by ultrasonography after estrus manifestation in six ewe of each group. Estrus events were observed twice a day during the BS of 35 days, and estrus [...]

Influência da condição corporal ao parto no balanço energético e desempenho reprodutivo de cabras leiteiras no pós-parto / Influence of body condition at calving on energy balance and reproductive performance of dairy goats in the postpartum

O estudo teve como objetivo avaliar a influência da condição corporal (CC) ao parto no balanço energético (BE) e o desempenho reprodutivo de cabras Alpinas no pós-parto. Foram utilizadas 68 cabras distribuídas em três grupos (G), sendo: G1- cabras com baixa CC (CC entre 1,5 e 2,5); G2: cabras com moderada CC (entre 2,75 e 3,5) e G3: cabras com alta CC (entre 3,75 e 5,0). Os animais receberam dieta (silagem de milho e concentrado, com 18% de proteína bruta e 1,7Mcal/kg de matéria seca de energia líquida) ad libitum. As avaliações foram feitas nas oito primeiras semanas de lactação, para determinação do BE, do intervalo do parto à primeira ovulação e ao primeiro estro e da concentração plasmática de progesterona. Os dados foram analisados por análise de variância a 5% de probabilidade. Não houve efeito da CC ao parto sobre o BE dos animais. Todas as cabras apresentaram BE negativo ao parto, com mudança para BE positivo aos 51, 58 e 64 dias pós-parto, respectivamente. Não houve diferença na concentração plasmática de progesterona nos três grupos, sendo caracterizada função luteal (concentração ≥1ng/dL) em apenas 5,9% dos animais avaliados. O intervalo do parto à primeira ovulação foi de 46 dias. Apenas 4,4% das cabras exibiram estro. Cabras leiteiras de média produção, entre 2,5 e 3,0kg de leite/dia, entram em BE negativo ao parto, independentemente da CC apresentada, influenciando negativamente o reinício da atividade ovariana no pós-parto.(AU)

The concentration of progesterone in the blood was used to study the effect of body condition score (BCS) on the post-partum ovarian activity of dairy goats. Sixty-eight female goats were distributed between three treatments. Treatment 1: goats with BCS between 1.00 and 2.75; Treatment 2: goats with BCS between 2.75 and 3.50; and Treatment 3: goats with BCS between 3.50 and 5.00. The goats had the blood collected immediately after birth, and from that time up to the eighth week post-partum at three day intervals. The progesterone analysis on the blood was used to determine the interval between the birth and the first ovulation. The females were teasing two times per day for estrus detection and determination of the time interval from birth to first estrus. No significant difference was found on the progesterone concentration between treatments. The luteal functionality was characterized in only 5.9% of goats, with a concentration higher than 1ng/mL. The period from birth to first ovulation was 46 days. The detectable estrus was found in only 4.4% of goats. The BCS at birth did not influence the recovery of ovarian activity of dairy goats.(AU)

Influência da condição corporal ao parto no balanço energético e desempenho reprodutivo de cabras leiteiras no pós-parto / Influence of body condition at calving on energy balance and reproductive performance of dairy goats in the postpartum

O estudo teve como objetivo avaliar a influência da condição corporal (CC) ao parto no balanço energético (BE) e o desempenho reprodutivo de cabras Alpinas no pós-parto. Foram utilizadas 68 cabras distribuídas em três grupos (G), sendo: G1- cabras com baixa CC (CC entre 1,5 e 2,5); G2: cabras com moderada CC (entre 2,75 e 3,5) e G3: cabras com alta CC (entre 3,75 e 5,0). Os animais receberam dieta (silagem de milho e concentrado, com 18% de proteína bruta e 1,7Mcal/kg de matéria seca de energia líquida) ad libitum. As avaliações foram feitas nas oito primeiras semanas de lactação, para determinação do BE, do intervalo do parto à primeira ovulação e ao primeiro estro e da concentração plasmática de progesterona. Os dados foram analisados por análise de variância a 5% de probabilidade. Não houve efeito da CC ao parto sobre o BE dos animais. Todas as cabras apresentaram BE negativo ao parto, com mudança para BE positivo aos 51, 58 e 64 dias pós-parto, respectivamente. Não houve diferença na concentração plasmática de progesterona nos três grupos, sendo caracterizada função luteal (concentração ≥1ng/dL) em apenas 5,9% dos animais avaliados. O intervalo do parto à primeira ovulação foi de 46 dias. Apenas 4,4% das cabras exibiram estro. Cabras leiteiras de média produção, entre 2,5 e 3,0kg de leite/dia, entram em BE negativo ao parto, independentemente da CC apresentada, influenciando negativamente o reinício da atividade ovariana no pós-parto.(AU)

The concentration of progesterone in the blood was used to study the effect of body condition score (BCS) on the post-partum ovarian activity of dairy goats. Sixty-eight female goats were distributed between three treatments. Treatment 1: goats with BCS between 1.00 and 2.75; Treatment 2: goats with BCS between 2.75 and 3.50; and Treatment 3: goats with BCS between 3.50 and 5.00. The goats had the blood collected immediately after birth, and from that time up to the eighth week post-partum at three day intervals. The progesterone analysis on the blood was used to determine the interval between the birth and the first ovulation. The females were teasing two times per day for estrus detection and determination of the time interval from birth to first estrus. No significant difference was found on the progesterone concentration between treatments. The luteal functionality was characterized in only 5.9% of goats, with a concentration higher than 1ng/mL. The period from birth to first ovulation was 46 days. The detectable estrus was found in only 4.4% of goats. The BCS at birth did not influence the recovery of ovarian activity of dairy goats.(AU)

Aspects and mechanisms of low fertility in anovulatory dairy cows

Postpartum anovulation is a natural process that is observed in most mammals, including women. In lactating dairy cows, the interval from calving to first ovulation typically averages 4 to 5 weeks, but a substantial proportion of cows have not resumed estrous cyclicity by 60 days postpartum. Extended delay in resumption of first postpartum ovulation is known to exert long-lasting detrimental effects on fertility in dairy cows including the lack of spontaneous estrus and subsequent timely insemination postpartum, but when anovular cows have the estrous cycle synchronized for artificial insemination (AI), still pregnancy per AI is reduced and the risk of pregnancy loss increased. Many risk factors exist for extended postpartum anovulatory periods such as negative nutrient balance and diseases, and these risk factors are also known to depress fertility by themselves. A key feature in anovular cows when inseminated is that they develop the ovulatory follicle under subluteal or low concentrations of progesterone. Progesterone from the corpus luteum is pivotal for follicle development, oocyte competence, embryo growth, and endometrial function; however, many of these effects exerted by progesterone are mediated either by secretion of gonadotropins influencing follicular function and oocyte competence or by endometrial histotroph secretion influencing embryo/conceptus growth and developmental biology

Aspects and mechanisms of low fertility in anovulatory dairy cows

Postpartum anovulation is a natural process that is observed in most mammals, including women. In lactating dairy cows, the interval from calving to first ovulation typically averages 4 to 5 weeks, but a substantial proportion of cows have not resumed estrous cyclicity by 60 days postpartum. Extended delay in resumption of first postpartum ovulation is known to exert long-lasting detrimental effects on fertility in dairy cows including the lack of spontaneous estrus and subsequent timely insemination postpartum, but when anovular cows have the estrous cycle synchronized for artificial insemination (AI), still pregnancy per AI is reduced and the risk of pregnancy loss increased. Many risk factors exist for extended postpartum anovulatory periods such as negative nutrient balance and diseases, and these risk factors are also known to depress fertility by themselves. A key feature in anovular cows when inseminated is that they develop the ovulatory follicle under subluteal or low concentrations of progesterone. Progesterone from the corpus luteum is pivotal for follicle development, oocyte competence, embryo growth, and endometrial function; however, many of these effects exerted by progesterone are mediated either by secretion of gonadotropins influencing follicular function and oocyte competence or by endometrial histotroph secretion influencing embryo/conceptus growth and developmental biology…(AU)

Efeitos da suplementação pré-parto sobre o desempenho produtivo, reprodutivo e perfil metabólico de vacas Nelore em pastejo

O objetivo deste trabalho foi avaliar os efeitos da suplementação durante o período pré-parto sobre o desempenho produtivo, reprodutivo e perfil metabólico de vacas Nelore em pastejo nos períodos pré e pós-parto, assim como no desenvolvimento corporal inicial da prole. Foram utilizadas 37 vacas Nelore pluríparas, com média inicial de 224 ± 2,6 dias de gestação, 534 ± 12,2 kg de peso corporal (PC) e 3,64 ± 0,07 (escala de 1 5) de escore de condição corporal (ECC), segundo delineamento em blocos completos casualizados, com dois tratamentos e quatro repetições. Os tratamentos foram controle: mistura mineral (MM; CON, n = 4) e suplementado: (SUP, n = 4): suplemento proteico-energético fornecido a 1,5 kg / animal / dia com 250g de PB / kg MS no período pré-parto. As avaliações estatísticas foram conduzidas por intermédio do procedimento GLIMMIX do SAS (versão 9.4), adotando-se = 0,10. Vacas suplementadas apresentaram maior GMD no pré e pós-parto (P < 0,10), maior ECC no pré-parto e maior PC durante o pós-parto (P < 0,10). Verificou-se tendência para maior EGS e produção de leite (P < 0,20) para vacas do grupo SUP. Não houve efeito de tratamento para EGSg, AOL, e nem efeito da suplementação materna pré-parto no PC ao nascimento e GMD das bezerras (P > 0,10). Não foram observadas diferenças significativas (P > 0,10) entre os níveis séricos e plasmáticos de metabólitos e hormônios, com exceção do colesterol total que foi maior para vacas SUP (P = 0,038). A suplementação durante o período pré-parto não influenciou o diâmetro do folículo dominante, subordinado e préovulatório (P > 0,10). Da mesma forma, as taxas de ciclicidade, concepção e prenhez não foram afetadas pelos tratamentos (P > 0,10). Entretanto, verificou-se tendência para a taxa de ciclicidade no início do protocolo (P = 0,157) e interação tratamento período para o diâmetro do folículo dominante (P = 0,074). Por fim, os dados encontrados não suportam uma sugestão de suplementação para vacas com adequada condição corporal no pré-parto, mas a observação de tendência para algumas variáveis demonstra a necessidade de novos estudos para confirmar o real benefício dessa estratégia para vacas de corte em pastejo.

The objective of this work was to evaluate the effects of supplementation during the precalving period on the productive, reproductive and metabolic profile of Nellore cows grazing in the pre and post-calving periods, as well as on the initial body development of the offspring. 37 pluriparous Nellore cows were used, with an initial mean of 224 ± 2.6 days of gestation, 534 ± 12.2 kg of body weight (BW) and 3.64 ± 0.07 (scale of 1 - 5) of score of body condition (ECC), second a complete randomized block design, with two treatments and four repetitions. The treatments were control: mineral mixture (MM; CON, n = 4) and supplemented: (SUP, n = 4): protein-energetic supplement supplied at 1.5 kg / animal / day with 250g of CP / kg DM in the period pre-partum. Statistical analyses were conducted using the GLIMMIX procedure of the SAS (version 9.4), adopting = 0.10. Supplemented cows had higher ADG in the pre and post-partum period (P <0.10), higher BCS in the prepartum period and greater BW during the postpartum period (P <0.10). There was a trend towards greater BFT and milk production (P <0.20) for cows in the SUP group. There was no effect of treatment for RFAT, REA, and no effect of pre-partum maternal supplementation in the BW at birth and ADG of the calves (P > 0.10). No significant diferences were observed (P > 0.10) between serum and plasma levels of hormones and metabolites, with the exception of total cholesterol which was higher for SUP cows (P = 0.038). Supplementation during the prepartum period did not influence the diameter of the dominant, subordinate and pre-ovulatory follicle (P> 0.10). Likewise, the rates of cyclicity, conception and pregnancy were not affected by the treatments (P> 0.10). However, there was a trend towards the cyclicity rate at the beginning of the protocol (P = 0.157) and treatment interaction over a period for the diameter of the dominant follicle (P = 0.074). Finally, the data found do not support a suggestion of supplementation for cows with adequate body condition in the prepartum period, but the trend observation for some variables demonstrates the need for further studies to confirm the real benefit of this strategy for grazing beef cows.

Impact of animal health on reproduction of dairy cows

[...] A wealth of information in the scientific literature is available linking diseases with depressed reproduction in dairy cows. Unfortunately, only few studies have established a causal relationship between a specific disease and fertility, and little is known about the mechanisms that underlie the decrease in pregnancy in dairy cows that had disease in early lactation. It is clear that dairy cows that suffer from disease processes have impaired resumption of postpartum ovulation, compromised fertilization and pre-and peri-implantation conceptus development, altered conceptus gene expression, increased pregnancy loss and, ultimately reduced pregnancy per insemination that causes an extension in time to pregnancy. Because mechanisms are poorly understood, no target intervention is available at this time to reverse the poor reproduction in cows that develop periparturient diseases, except methods to induce cyclicity in anovular cows or to improve insemination rate in cows not detected in estrus. Regardless of a better understanding of the underlying biology of poor fertility in diseased cows, a pivotal approach is to implement strategies that mitigate the risk factors that predispose cows to disease. Such interventions include, but are not limited to, improving transition cow management and grouping, proper dietary formulation to prevent periparturient diseases associated with intermediary and mineral metabolism, strategies for reducing calving-related disorders, and methods to prevent mastitis and lameness. Future developments in target strategies to improve reproduction of cows suffering from peripartum diseases will require a better understanding of the impaired biological processes that compromise establishment and maintenance of pregnancy in this subfertile population of cows.