Effect of solar radiation on Holstein heifers' physiological variables and grazing behavior

The objective was to assess the physiological and behavioral variables of pasture-raised Holstein heifers on the basis of their coat color. Eight heifers were used, four with black coat, and four with white coat. In the morning and afternoon periods, their physiological variables were measured, namely respiratory rate (RR, mov min. -1), rectal temperature (TR, ºC), and coat surface temperature (TS, ºC). The behavior analysis considered the site (sun or shade), position (standing or lying down), and activities (idleness, rumination, grazing, and others). The data of the physiological variables were assessed through analysis of variance, and significance, through Tukey's test at 5%, while behavioral data were assessed using the Chi-squared test (SAS Software). There was a difference for all of the heifers' physiological variables as a function of coat color (p < 0.0001) and period (p < 0.0001), with black ones showing greater results than white ones as to all physiological variables in the afternoon period (p < 0.0001). Grazing behavior is reduced during the hottest hours of the day. We conclude that solar radiation changes the physiological variables and grazing behavior of pasture-raised Holstein heifers.(AU)

Oxidative activity of corpus luteum and ovarian parenchyma in Bos taurus indicus heifers

Abstract The aim of this study was to evaluate the oxidative stress in ovaries and corpus luteum (CL) of Bos taurus indicus females and the oxidant effect of CL in ovarian tissues in regions near, intermediate, or distant from it. Ovaries (n=12) of Nelore heifers (n=6) were collected from a slaughterhouse and fragmented. Experiment 1, each ovary was obtained from three fragments, resulting in 18 fragments of ovaries with CL (OV+CL) and another 18 fragments of ovaries without CL (OV-CL). Three fragments were generated from CL, totaling 18 CL fragments. In experiment 2, the ovarian fragments were removed from specific regions near, intermediate, or distant from the CL. All the fragments were placed in Eppendorf-type microtubes (1 mL), kept in a thermal container at 4 ºC, and then stored in a -80 ºC freezer for analysis of oxidative stress (TBARS and NBT) and antioxidant potential (FRAP and ABTS). In the antioxidant activity analysis, luteal tissues showed more antioxidant activity than ovarian tissue (FRAP = P < 0.0001; ABTS = P < 0.02). In the oxidative stress analysis, CL had lower levels of reactive oxygen species (ROS; TBARS = P < 0.03; NBT = P < 0.0001) than ovarian tissues. There was no difference in antioxidant activity and oxidative stress between the fragments obtained from different regions (OV+CL versus OV-CL; P > 0.05). The presence of CL in the ovaries of Bos taurus indicus females did not influence the oxidative stress or antioxidant potential of the gonad. Thus, the removal of ovarian fragments with or without the presence of CL indicates that biotechnologies such as in vitro follicle cultivation is possible.

Antral follicle count classification selects fertile heifers without influencing the carcass traits / A classificação da contagem folicular antral seleciona novilhas mais férteis sem influenciar as características da carcaça

This study aimed to evaluate the ovarian structure, estrus intensity, ultrasound carcass measurements, and pregnancy rate of Nelore breed heifers and cows in accordance with antral follicle counts (AFCs). We evaluated 503 heifers and 565 Nelore cows, with a mean age of 15.5±2.2 and 69.8±36.1 months, respectively, submitted to a fixed-time artificial insemination (FTAI) protocol. On day zero, all bovine females were examined using ultrasound to determine the AFC. The mean AFC of the heifers and cows were 20±8.6 and 22.5±8.4, respectively. The rib-eye area (REA) and fat thickness (FT) of the heifers (n = 119 for REA and n = 219 for FT) were measured using ultrasound imaging. The average conception rates at the first FTAI and at the end of the breeding season were 35.8% and 57.5%, respectively, for heifers and 45.1% and 78.9%, respectively, for cows. We demonstrated that the probability of pregnancy at the first FTAI and at the end of the breeding season for both young heifers and cows increased as the AFC decreased (P>0.001 and P=0.0123, respectively). FT and REA showed no correlation with AFC in heifers. The intensity of estrus expression was negatively correlated with AFC (−0.46; P<0.0001). In conclusion, Nelore heifers and cows with low AFC had a high probability of pregnancy during the entire breeding season. Thus, AFC can be used as a tool to select heifers with increased fertility without affecting carcass traits (REA and FT).

Este estudo teve como objetivo avaliar as estruturas ovarianas, intensidade do cio, medidas de carcaça por ultrassonografia e taxa de gestação de novilhas e vacas da raça Nelore com diferentes contagens de folículos antrais (CFA). Avaliamos 503 novilhas e 565 vacas Nelore, com idade média de 15,5 ± 2,2 e 69,8 ± 36,1 meses, respectivamente, submetidas a um protocolo de inseminação artificial em tempo fixo (IATF). No dia zero, todas as fêmeas foram examinadas por ultrassom para determinar a CFA. A CFA média das novilhas foi de 20 ± 8,6 e a das vacas foi de 22,5 ± 8,4 folículos. A área de olho de lombo (AOL) e a espessura de gordura (EG) das novilhas (n = 119 para AOL e n = 219 para EG) foram medidas utilizando imagens ultrassonográficas. As taxas médias de concepção na primeira IATF e no final da estação de monta foram de 35,8% e 57,5% e 45,1% e 78,9% para as novilhas e vacas, respectivamente. Demonstramos que a probabilidade de gestação na primeira IATF e no final da estação de monta, tanto para novilhas jovens quanto para vacas, foi maior quando a CFA era menor (P>0,001 e P=0,0123, respectivamente). A espessura da gordura e a AOL não mostraram nenhuma correlação com a CFA. A intensidade da expressão do cio foi negativamente correlacionada com o CFA (-0,46; P < 0,0001). Em conclusão, novilhas jovens e vacas da raça Nelore com menor CFA apresentam maior probabilidade de prenhez durante toda a estação de monta. Nenhuma relação entre a CFA e as características de carcaça foram observadas em novilhas Nelore. A CFA pode ser usada como uma ferramenta de seleção de novilhas com maior fertilidade sem influenciar as características de carcaça (AOL e EG).

Association between chronic Anaplasma marginale and Babesia spp. infection and hematological parameters of taurine heifers / Associação entre infecção crônica por Anaplasma marginale e Babesia spp. e parâmetros hematológicos de novilhas taurinas

The aim of this study was to investigate the association between chronic Anaplasma marginale and Babesia spp. infection and hematological parameters of pregnant and non-pregnant taurine heifers. Blood samples from 94 females were collected on the first day (D-10) of timed artificial insemination (TAI) protocol and on pregnancy diagnosis (D+34). Hematological parameters were determined and compared between pregnant (PG) and non-pregnant (NPG) heifers, and within group at different sampling days. Real-time PCR (qPCR) was used to determine A. marginale and Babesia bovis infection, and for absolute quantification of Babesia spp. between PG and NPG groups. Correlation analysis was performed between the number of gDNA copies (CN) of Babesia spp. and hematological parameters. On D-10, mean hemoglobin concentration was higher for NPG, and hematocrit and total plasma protein were higher on D+34 for both groups. There was no difference in Babesia spp. CN between groups. In the first qPCR, all heifers were positive for A. marginale and B. bovis. Significant correlations were found between hemoglobin and erythrocyte and between hemoglobin and hematocrit (r = 0.8082 and r = 0.3009, respectively). Low levels of A. marginale and Babesia spp. did not affect hematological parameters of chronically infected pregnant and non-pregnant taurine heifers.(AU)

O objetivo deste estudo foi investigar a associação entre infecção crônica por Anaplasma marginale e Babesia spp. e parâmetros hematológicos de novilhas taurinas prenhes e não prenhes. Sangue de 94 fêmeas foi coletado no primeiro dia (D-10) do protocolo de inseminação artificial em tempo fixo (IATF) e no diagnóstico de gestação (D+34). Parâmetros hematológicos foram comparados entre novilhas prenhes (PG) e não prenhes (NPG) e dentro dos grupos entre dias de coleta. Usando-se PCR em tempo real (qPCR), determinou-se a infecção por A. marginale e Babesia bovis e quantificação absoluta de Babesia spp. Entre os grupos PG e NPG. A análise de correlação foi realizada entre o número de cópias (CN) de Babesia spp. e parâmetros hematológicos. No D-10, a concentração de hemoglobina foi maior para NPG e hematócrito, e proteína plasmática total foram maiores em D+34 para ambos os grupos. Não houve diferença para CN de Babesia spp. entre os grupos. Na primeira qPCR, todas as novilhas foram positivas para A. marginale e B. bovis. Correlações significativas foram encontradas entre hemoglobina/eritrócito e hemoglobina/hematócrito (r=0,8082 e r=0,3009, respectivamente). Baixos níveis de A. marginale e Babesia spp. não afetaram os parâmetros hematológicos de novilhas taurinas prenhes e não prenhes cronicamente infectadas.(AU)

Energy supplements for beef heifers on cool season pastures: a database analysis / Uso de suplemento energético para novilhas de corte em pastagens de estação fria: análise de banco de dados

Pooled data analysis is an analytical method that combines results from multiple studies. This technique provides a more robust estimate of the effects of an investigation. We performed a database analysis from seventeen experiments developed at Federal University of Santa Maria, Rio Grande do Sul state, Brazil, between 1999 and 2017 to characterize individual performance per area and stocking rate with or without supplementation of replacement heifers grazing winter pastures. Data were separated into two groups: with and without energy supplement provision, and into five subgroups based on supplement levels. Heifers from both groups were maintained under similar forage biomass and leaf blade allowance. Statistical analyses were run on R software using a 'meta' package. Supplement supply increased average daily gain and gain of body condition scores by 11.1% and 20.0%, respectively. Supplement levels higher than 1.2% of body weight resulted in higher weight gain per area, with the stocking rate increasing with higher supplement levels.

Análise conjunta de dados é um método analítico que integra os resultados de muitos estudos. Essa técnica fornece uma estimativa mais robusta sobre os efeitos de uma investigação. Com o objetivo de caracterizar o desempenho individual, por área e a taxa de lotação com uso ou não de suplementos para novilhas de reposição mantidas em pastagem de inverno, foi realizada uma análise de banco de dados de dezessete experimentos conduzidos na Universidade Federal de Santa Maria (UFSM), RS, Brasil, entre 1999 e 2017. Os dados foram estratificados em dois grupos: com e sem suplemento energético e cinco subgrupos de acordo com o nível de suplemento. As novilhas de ambos os grupos foram mantidas em similar massa de forragem e oferta de lâminas foliares. As análises estatísticas foram executadas no software R, pacote 'meta'. O fornecimento de suplemento aumentou o ganho médio diário em 11.1% e em 20.0% o ganho no escore de condição corporal. Níveis de fornecimento maiores que 1.2% do peso corporal proporcionaram o maior ganho de peso por área e a taxa de lotação aumenta à medida que os níveis de suplemento aumentam.

Maternal instinct of imported meat direction cattle and ethology of their calves

The examination of maternal qualities in the ethology of cows and their young offspring, derived from the study on adaptability and productivity of second and third-generation Aberdeen Angus cattle imported to Kazakhstan from Canadian and European selection, is presented in this paper. The findings indicate that Canadian heifers, belonging to the second generation, displayed extended feeding behavior throughout the day, dedicating 33.2 minutes or 2.2% more time to feeding compared to their European counterparts (P < 0.001). Similar disparities between groups were observed in the duration of the ruminant process. Moreover, Canadian heifers consumed water for an additional 2 minutes or 0.6%, which can be attributed to their higher daily feed intake. The calving process of Aberdeen Angus cows generally proceeded smoothly, demonstrating a well-developed maternal instinct towards their offspring. Notably, calves born from Canadian cows exhibited greater agility and achieved the ability to stand on their feet in a shorter time, with an average duration of 41.0 ± 1.60 minutes, which was 11.7% faster than European calves. Additionally, Canadian calves displayed a shorter time to locate their mother's breast, with an average duration of 68.0 ± 7.70 minutes.(AU)

Oxidative activity of corpus luteum and ovarian parenchyma in Bos taurus indicus heifers

The aim of this study was to evaluate the oxidative stress in ovaries and corpus luteum (CL) of Bos taurus indicus females and the oxidant effect of CL in ovarian tissues in regions near, intermediate, or distant from it. Ovaries (n=12) of Nelore heifers (n=6) were collected from a slaughterhouse and fragmented. Experiment 1, each ovary was obtained from three fragments, resulting in 18 fragments of ovaries with CL (OV+CL) and another 18 fragments of ovaries without CL (OV-CL). Three fragments were generated from CL, totaling 18 CL fragments. In experiment 2, the ovarian fragments were removed from specific regions near, intermediate, or distant from the CL. All the fragments were placed in Eppendorf-type microtubes (1 mL), kept in a thermal container at 4 ºC, and then stored in a -80 ºC freezer for analysis of oxidative stress (TBARS and NBT) and antioxidant potential (FRAP and ABTS). In the antioxidant activity analysis, luteal tissues showed more antioxidant activity than ovarian tissue (FRAP = P < 0.0001; ABTS = P < 0.02). In the oxidative stress analysis, CL had lower levels of reactive oxygen species (ROS; TBARS = P < 0.03; NBT = P < 0.0001) than ovarian tissues. There was no difference in antioxidant activity and oxidative stress between the fragments obtained from different regions (OV+CL versus OV-CL; P > 0.05). The presence of CL in the ovaries of Bos taurus indicus females did not influence the oxidative stress or antioxidant potential of the gonad. Thus, the removal of ovarian fragments with or without the presence of CL indicates that biotechnologies such as in vitro follicle cultivation is possible.(AU)

Differentially methylated regions identified in bovine embryos are not observed in adulthood

The establishment of epigenetic marks during the reprogramming window is susceptible to environmental influences, and stimuli during this critical stage can cause altered DNA methylation in offspring. In a previous study, we found that low levels of sulphur and cobalt (low S/Co) in the diet offered to oocyte donors altered the DNA methylome of bovine embryos. However, due to the extensive epigenetic reprogramming that occurs during embryogenesis, we hypothesized that the different methylation regions (DMRs) identified in the blastocysts may not maintain in adulthood. Here, we aimed to characterize DMRs previously identified in embryos, in the blood and sperm of adult progenies of two groups of heifers (low S/Co and control). We used six bulls and characterized the DNA methylation levels of KDM2A, KDM5A, KMT2D, and DOT1L genes. Our results showed that all DMRs analysed in both groups and tissues were hypermethylated unlike that noticed in the embryonic methylome profiles. These results suggest that embryo DMRs were reprogrammed during the final stages of de novo methylation during embryogenesis or later in development. Therefore, due to the highly dynamic epigenetic state during early embryonic development, we suggest that is essential to validate the DMRs found in embryos in adult individuals.(AU)

Bacillary hemoglobinuria in a cow

Clinical History: A 436 kg, 2-year-old, pregnant Angus cross cow was presented for necropsy with a history of sudden death during calving season. Two other heifers on the property recently had late term abortions with the calves having to be pulled out from the birth canal. Gross Findings: The subcutaneous tissue, omentum, mesentery, perirenal adipose tissue, and intima of the major vessels were diffusely and markedly yellow (Figure 1). The right liver lobe had a large (15x11x7 cm) area of pale tan discoloration covered by a thin layer of fibrin. On the cut surface, this area was pale red and dry (Figure 2). Throughout the remaining hepatic parenchyma were irregularly shaped, serpiginous, dark green to black tracks. Some of these tracks contained adult Fasciola hepatica flukes in the lumen. The gallbladder was distended and filled with large amounts of dark green, thick bile. The kidneys were diffusely dark red with disseminated pinpoint, dark red foci in the cortex (Figure 3). The urinary bladder contained approximately 300 mL of dark red urine (Figure 4). The brain had a slight yellow discoloration. Approximately 300 mL of red-tinged fluid was in the thorax. Large numbers of fibrous adhesions were present between the visceral pleura, the parietal pleura, and the pericardium. Approximately 200 mL of red-tinged fluid was in the pericardial sac. There was extensive hemorrhage on the epicardium.

Nitrogen nutrition index and morphogenesis in Alexandergrass of the Central Depression of Rio Grande do Sul / Índice de nutrição nitrogenada e morfogênese em papuã na Depressão Central do Rio Grande do Sul

This study assessed the nitrogen nutrition index, morphogenic characteristics and tiller structure of Alexandergrass (Urochloaplantaginea (LINK) Hitch) pasture submitted to different nitrogen (N) levels (zero, 150 or 300 kg ha-1 of N). The experimental design was entirely randomized with repeated measures arrangement. The experimental animals were Angus heifers under rotational stocking grazing method. The number of animals was variable to keep 30±5 cm post-grazing sward height. Nitrogen nutrition index increased linearly according N levels (Y = 59.8 + 0.1216N; P < 0.0001; r²=0.53). The leaf appearance rate adjusted to a positive linear regression model according the thermal sum (TS) with zero of N (Y0N = 0.0077 + 0.0000087TS; P = 0.0308; r² = 0.72) and 150 kg ha-1 of N (Y150N = 0.0020 + 0.000021 TS; P = 0.0022; r² = 0.92). The use of 300 kg ha-1 of N did not alter the leaf appearance rate (0.0124 leaf degree-days-1). The use of up to 300 kg ha-1 of N increases the Alexandergrass nitrogen content. The leaf appearance rate in Alexandergrass is modified using N while the morphogenic characteristics leaf expansion, stem expansion, phyllochron, leaf lifespan, leaf elongation duration and tiller structure are not altered by N utilization.

Este trabalho teve como objetivo avaliar o índice de nutrição nitrogenada, as características morfogênicas e a estrutura dos perfilhos de papuã (Urochloa plantaginea (LINK) Hitch) submetidos a diferentes níveis de nitrogênio (N) (zero, 150 ou 300 kg ha-1 de N). O delineamento experimental foi inteiramente casualizado com medidas repetidas no tempo. Os animais experimentais foram novilhas Angus em regime de pastejo rotacionado. O número de animais foi variável para manter 30 ± 5 cm de altura do pasto pós-pastejo. O índice de nutrição com nitrogênio aumentou linearmente de acordo com os níveis de N (Y = 59,8 + 0,1216N; P < 0,0001; r² = 0,53). A taxa de aparecimento de folhas ajustou-se ao modelo de regressão linear positiva de acordo com a soma térmica (TS) com zero de N (Y0N = 0,0077 + 0,0000087TS; P = 0,0308; r² = 0,72) e 150 kg ha-1 de N (Y150N = 0,0020 +0,000021 TS; P = 0,0022; r² = 0,92). O uso de 300 kg ha-1 de N não alterou a taxa de aparecimento de folhas (0,0124 folha grau-dia-1). O uso de até 300 kg ha-1 de N aumenta o teor de nitrogênio do papuã. A taxa de aparecimento de folhas em papuã é modificada usando N, enquanto que as características morfogênicas expansão foliar, expansão de colmo, filocrono, duração de vida das folhas, duração da elongação foliar e a estrutura dos perfilhos não são alteradas pela utilização de N.

Applying assisted reproductive technology and reproductive management to reduce CO2-equivalent emission in dairy and beef cattle: a review

Methane emission from beef and dairy cattle combined contributes around 4.5-5.0% of total anthropogenic global methane. In addition to enteric methane (CH4) produced by the rumen, cattle production also contributes carbon dioxide (CO2) (feed), nitrous oxide (N2O) (feed production, manure) and other CH4 (manure) to the total greenhouse gas (GHG) budget of beef and dairy production systems. The relative contribution in standard dairy systems is typically enteric CH4 58%, feed 29% and manure 10%. Herds with low production efficiency can have an enteric CH4 contribution up to 90%. Digestibility of feed can impact CH4 emission intensity. Low fertility herds also have a greater enteric CH4 contribution. Animals with good feed conversion efficiency have a lower emission intensity of CH4/kg of meat or milk. Feed efficient heifers tend to be lean and have delayed puberty. Fertility is a major driver of profit in both beef and dairy cattle, and it is highly important to apply multi-trait selection when shifting herds towards improved efficiency and reduced CH4. Single nucleotide polymorphisms (SNPs) have been identified for feed efficiency in cattle and are used in genomic selection. SNPs can be utilized in artificial insemination and embryo transfer to increase the proportion of cattle that have the attributes of efficiency, fertility and reduced enteric CH4. Prepubertal heifers genomically selected for favourable traits can have oocytes recovered to produce IVF embryos. Reproductive technology is predicted to be increasingly adopted to reduce generation interval and accelerate the rate of genetic gain for efficiency, fertility and low CH4 in cattle. The relatively high contribution of cattle to anthropogenic global methane has focussed attention on strategies to reduce enteric CH4 without compromising efficiency and fertility. Assisted reproductive technology has an important role in achieving the goal of multiplying and distributing cattle that have good efficiency, fertility and low CH4.(AU)

Use of new recombinant proteins for ovarian stimulation in ruminants

Currently, gonadotropin products (follicle stimulating hormone, FSH, and luteinizing hormone, LH) used in animal reproduction are produced by extraction and purification from abattoir-derived pituitary glands. This method, relying on animal-derived materials, carries the potential risk of hormone contamination and pathogen transmission. Additionally, chorionic gonadotropins are extracted from the blood of pregnant mares (equine chorionic gonadotropin; eCG) or the urine of pregnant women (human chorionic gonadotropin; hCG). However, recent advancements have introduced recombinant gonadotropins for assisted animal reproduction therapies. The traditional use of FSH for superovulation has limitations, including labor requirements and variability in superovulation response, affecting the success of in vivo (SOV) and in vitro (OPU/IVEP) embryo production. FSH treatment for superstimulation before OPU can promote the growth of a homogenous follicular population and the recovery of competent oocytes suitable for IVEP procedures. At present, a single injection of a preparation of long-acting bovine recombinant FSH (rFSH) produced similar superovulation responses resulting in the production of good-quality in vivo and in vitro embryos. Furthermore, the treatment with eCG at FTAI protocol has demonstrated its efficacy in promoting follicular growth, ovulation, and P/AI, mainly in heifers and anestrous cows. Currently, treatment with recombinant glycoproteins with eCG-like activity (r-eCG) have shown promising results in increasing follicular growth, ovulation, and P/AI in cows submitted to P4/E2 -based protocols. Bovine somatotropin (bST) is a naturally occurring hormone found in cows. Recombinant bovine somatotropin (rbST), produced through genetic engineering techniques, has shown potential in enhancing reproductive outcomes in ruminants. Treatment with rbST has been found to improve P/IA, increase donor embryo production, and enhance P/ET in recipients. The use of recombinant hormones allows to produce non-animal-derived products, offering several advantages in assisted reproductive technologies for ruminants. This advancement opens up new possibilities for improving reproductive efficiency and success rates in the field of animal reproduction.(AU)

Lipopolysaccharide effects on activation and apoptosis of primordial ovarian follicles in heifers / Efeitos de lipopolissacarídeos na ativação e apoptose de folículos ovarianos primordiais em novilhas

The objective of the present study was to evaluate the effect of lipopolysaccharide (LPS) administration on activation and apoptosis of primordial follicles. There was no difference in the total number of follicles as well as in the different types of follicles. Furthermore, the LPS challenge didn't modulate the expression of genes related with ovarian reserve (HAM), oocyte survival (Survivin), activation rate (Pten, KIT, KITL1, KITL2, AKT1, SIRT1), and follicular abnormalities. Therefore, the LPS exposure with 24h interval had no effect on activation rate and primordial follicles abnormalities, and also had no effect on expression of anti-apoptotic genes and genes related with ovarian reserve, oocyte survival, activation rate, and primordial follicles abnormalities.

O objetivo do presente estudo foi avaliar o efeito da administração de lipopolissacarídeo (LPS) na ativação e a apoptose de folículos primordiais. Dez novilhas saudáveis (Bos taurus taurus), com idade média de 14 meses, alojadas em sistema de confinamento e alimentadas com TMR, foram utilizadas neste experimento. Os animais foram distribuídos aleatoriamente em dois grupos: grupo LPS (LPS; n = 5), que recebeu duas injeções intravenosas de 0,5µg/kg de peso corporal de lipopolissacarídeo (Sigma Aldrich®) diluído em 2mL de solução salina (0,9% de NaCl), com intervalo de 24h; e grupo controle (CTR; n = 5), que recebeu duas injeções intravenosas de 2mL de solução salina (0,9% de NaCl), com intervalo de 24h. A primeira injeção de LPS foi realizada no d 1, e no d 5 os animais foram abatidos, os ovários foram pesados e as amostras dos ovários foram coletadas para avaliação histológica e molecular. Não houve diferença no número total de folículos, bem como nos diferentes tipos de folículos. Além disso, o desafio com LPS não modulou a expressão de genes relacionados à reserva ovariana (HAM), à sobrevivência oocitária (Survivin), à taxa de ativação (Pten, KIT, KITL1, KITL2, AKT1, SIRT1) e às anormalidades foliculares. Portanto, a exposição ao LPS com intervalo de 24h não teve efeito sobre a taxa de ativação e as anormalidades dos folículos primordiais, bem como não teve efeito sobre a expressão de genes antiapoptóticos e de genes relacionados com a reserva ovariana, a sobrevivência oocitária, a taxa de ativação e as anormalidades dos folículos primordiais.

Prohibition of hormones in animal reproduction: what to expect and what to do?

As our understanding of ovarian function in cattle has improved, our ability to control it has also increased. The development of Fixed-Time Artificial Insemination (FTAI) protocols at the end of the 20th century has increased exponentially the number of animals inseminated over the last 20 years. The main reasons for this growth were the possibility of obtaining acceptable pregnancy rates without heat detection and, above all, the induction of cyclicity in suckled cows in postpartum anestrus and prepubertal heifers at the beginning of the breeding season. Most FTAI treatments in South America have been based on the use of progesterone (P4) releasing devices and estradiol to synchronize both follicular wave emergence and ovulation, with pregnancy rates ranging from 40 to 60%. These protocols are implemented on a regular basis, allowing producers access to high-quality genetics, and increasing the overall pregnancy rates during the breeding season. In addition, it provided the professionals involved in these programs with a new source of income and the diversification of their practices into activities other than their usual clinical work. Many of these practices are now apparently at risk from restrictions on the use of estradiol by the European Union (EU) and other countries. However, the development of alternative protocols based on GnRH, with P4 devices and eCG and other new products that are not in the market yet will allow us to adapt to the new times that are coming. Logically, the challenge has already been raised and we must learn to use alternative protocols to try to continue increasing the use of this technology in beef and dairy herds. The objective of the present review is to describe the main aspects of banning estradiol in livestock production, the negative impacts on reproductive efficiency, and to present some alternative FTAI protocols for dairy and beef cattle.(AU)

The in vitro effects of n-3 fatty acids on immune response regulation of bovine ex vivo endometrial explants / Os efeitos in vitro dos ácidos graxos n-3 na regulação da resposta imune de explantes endometriais bovinos ex vivo

Fatty acids are considered metabolic intermediaries, although new facts indicate they also work as signaling molecules with different roles in the immune response. Based on that, in this study, we investigated the anti-inflammatory effects of n-3 polyunsaturated fatty acids (PUFAs) as eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and α-linolenic acid (LNA) in ex vivo bovine endometrial explants. For this, two groups were formed: (1) LPS-challenged and (2) control, both to evaluate the accumulation of proinflammatory cytokines as interleukin 1ß (IL1B) and interleukin 6 (IL6). To develop the study, bovine female reproductive tracts from non-pregnant Angus heifers without evidence of reproductive diseases were selected. Endometrial explants were processed and treated for 24 h with EPA, DHA, and LNA in five different concentrations (0µM, 50µM, 100 µM, 200µM and 400 µM) and then, challenged with LPS for 24 h. Supernatants were collected to evaluate the concentration of IL1B and IL6 by ELISA. Explants treated with EPA from control groups reduced the concentrations of ILB (200µM) and IL6 (400 µM), and IL6 (50 µM; 100 µM) from the LPS-challenged group. DHA decreased the accumulation of IL1B and IL6 at 200 µM on explants from the LPS-challenged group, and 200 µM reduced IL6 from the control group. In contrast, explants treated with LNA only reduced the accumulation of IL1B to 400µM (from both groups). In conclusion, the EPA acid is the best anti-inflammatory option to decrease the concentration of both pro-inflammatory cytokines (IL1B and IL6) from LPS-challenged and control groups in bovine endometrial explants; while LNA evidence to be the last option to promote an anti-inflammatory response.(AU)

Os ácidos graxos são considerados intermediários metabólicos, embora novos fatos indiquem que eles também atuem como moléculas sinalizadoras com diferentes papéis na resposta imune. Dessa forma, este estudo investigou os efeitos anti-inflamatórios de ácidos graxos poliinsaturados n-3 (PUFAs) como ácido eicosapentaenóico (EPA), ácido docosahexaenóico (DHA) e ácido α-linolênico (LNA) em explantes endometriais ex vivo de bovinos. Para tal, o experimento foi divido em dois grupos: (1) Desafiado-LPS e (2) Controle, para que então pudesse avaliar o acúmulo de citocinas pró-inflamatórias como interleucina 1ß (IL1B) e interleucina 6 (IL6). Foram selecionados tratos reprodutivos de fêmeas bovinas de novilhas Angus não prenhes sem evidência de doenças reprodutivas. Explantes endometriais foram processados e tratados por 24h com EPA, DHA e LNA em cinco concentrações diferentes (0µM, 50µM, 100 µM, 200µM e 400 µM) e, em seguida, desafiados com LPS por mais 24h. Os sobrenadantes foram colhidos para avaliar a concentração de IL1B e IL6 pelo teste de ELISA. Os explantes tratados com EPA dos grupos de controle reduziram as concentrações de ILB (200 µM) e IL6 (400 µM) e no grupo desafiado com LPS houve redução das concentrações de IL6 (50 µM; 100 µM). Nos explantes do grupo desafiado com LPS, o DHA diminuiu o acúmulo de IL1B e IL6 nas concentrações de 200 µM, e no grupo controle reduziu IL6 nas concentrações de 200 µM, enquanto os explantes tratados com LNA reduziram apenas o acúmulo de IL1B a 400 µM (de ambos os grupos). Em conclusão, o ácido EPA provou ser a melhor opção anti-inflamatória para diminuir a concentração de ambas as citocinas pró-inflamatórias (IL1B e IL6) de grupos desafiados com LPS e controle em explantes endometriais bovinos; enquanto o LNA evidencia ser a opção menos viável para promover uma resposta anti-inflamatória.(AU)

Effect of ovarian status on reproductive performance in dairy heifers inseminated with sexed semen

Background: The intensive reproductive management in the dairy farms requires inclusion of a large group of replacement heifers in the breeding program for a shorter period. In this aspect, a creation of effective estrus synchronization protocols with timed artificial insemination (TAI) by sexed semen and optimization of the current ones have a crucial role for obtaining high pregnancy rate. These protocols are beneficial, because they led to reduced interval to first AI, lack of need for estrus detection, and allow obtaining a large group of female calves for on time. Because of limited fertilizing potential of sexed spermatozoa this type of semen is applied mainly for heifers, as fertility is higher compared to lactating cows. The main objective of the present study was to investigate the effect of ovarian status on the reproductive performance in dairy heifers subjected to estrus synchronization and timed artificial insemination with sexed semen. Materials, Methods & Results: Forty-eight Holstein healthy heifers separated in 2 groups were subjected to PGF2α-GnRH pre-treatment and Ovsynch or PRID-5-day estrus synchronization protocol and timed artificial insemination (TAI) with sex-sorted semen, staring 6 days after end of the hormonal pre-treatment. The ovarian status (presence of follicles with or not a corpus luteum) of the heifers at the begin of the treatment, on day of TAI and pregnancy rate in different groups were determined and compared. Additionally, the ovarian status at the begin of the treatment, ovarian status and size of preovulatory follicle (PF) on day of TAI and total values for both groups according to reproductive performance (pregnant or non-pregnant) were also analyzed. On day of TAI the animals with PF and a lack of corpus luteum (CL) in both groups were more that those with PF and CL (39.3% and 30% vs. 60.7 % and 70%), with significant (P < 0.05) difference in PRID-5-day group. The pregnancy rate tended to be higher in PRID-5 day than Ovsynch treatment (65% vs. 35.7%). A higher percentage (100% and 67.9%) of the pregnant animals in both treatments had not CL on day of TAI, and the size of the PF (1.58 ± 0.12 cm and 1.64 ± 0.13 cm) was increased (P < 0.05). Similar effects of the ovarian status on reproductive performance were obtained after a comparison of the total values between pregnant and non-pregnant animals. The percentage of heifers with observed PF without CL on day of TAI was significantly greater (P < 0.05) in pregnant compared to non-pregnant group (91.3% vs. 40%). The opposite dependence was determined for the parameter presence of follicles and corpus luteum (8.7% vs. 60%; P < 0.05). Furthermore, the size of the PF measured immediately before TAI was increased in animals became pregnant (1.60 ± 0.12 cm vs. 1.34 ± 0.17 cm; P < 0.05). Discussion: The analysis of the obtained results showed that the ovarian status on day of TAI affects the reproductive performance in dairy heifers subjected to estrus synchronization and timed artificial insemination with sexed semen. Hormonal pre-treatment with onset of PRID-5-day protocol 6 days later and TAI with sex-sorted semen ensure acceptable pregnancy rate. The greater preovulatory follicle and a lack of corpus luteum before insemination provide significantly (P < 0.05) more pregnant animals, compared to the cases when CL is presented. Ultrasound determination of the ovarian function before insemination can be used in selection of heifers for TAI with sex-sorted semen.

Antral follicle count, productive and reproductive parameters in Bos indicus and Bos indicus-taurus prepubertal heifers with early puberty induction / Contagem de folículos antrais, parâmetros produtivos e reprodutivos em novilhas pré-púberes Bos indicus e Bos indicus-taurus com indução precoce de puberdade

Prepubertal Nelore (G-N = 15) and crossbred Nelore x Aberdeen Angus heifers (G-NA = 15) were used for this study. AFC, live weight, body condition score (BCS), ovary and dominant follicle (DF) diameters were determined in each animal. Puberty induction was performed by insertion of a 4th use progesterone device (D0) which was removed on D12. Also, 1 mg estradiol benzoate was administered, and estrus intensity was classified (D12). At D21, the presence and diameter of the corpus luteum (CL) were registered. AFC was highly repeatable, regardless of hormone induction in both G-N (r=0.79) and G-NA (r=0.90). The mean AFC was greater in G-N compared to G-NA (24.2±8.5 vs. 17.7±9.0 follicles). A variation in BCS throughout the study occurred in G-NA, but not in G-N. The average weight gain (AWG) was greater in G-NA compared to G-N (0.69±0.33 vs. 0.40±0.29kg/day). The G-NA resulted in a larger diameter of DF at D12 than G-N (11.6±2.7 vs. 9.3±1.5mm). In conclusion, AFC was greater in Nelore heifers, although in both breeds this count was highly repeatable during puberty induction. Crossbred heifers had greater BCS and AWG with greater diameter of DF, indicating higher precocity when compared to Nelore heifers.

Novilhas pré-púberes Nelore (G-N=15) e mestiças Nelore x Aberdeen Angus (G-NA=15) foram utilizadas neste estudo. CFA, peso vivo, escore de condição corporal (ECC), diâmetros do ovário e folículo dominante (FD) foram determinados em cada animal. A indução da puberdade foi realizada pela inserção de um dispositivo de progesterona de quarto uso (D0), que foi retirado no D12. Além disso, 1mg de benzoato de estradiol foi administrado e a intensidade do estro foi classificada (D12). No D21, foram registrados a presença e o diâmetro do corpo lúteo (CL). A CFA foi altamente repetível, independentemente da indução hormonal em G-N (r=0,79) e G-NA (r=0,90). A CFA média foi maior em G-N em comparação com G-NA (24,2±8,5 vs. 17,7±9,0 folículos). Uma variação no ECC ao longo do estudo ocorreu em G-NA, mas não em G-N. O ganho de peso médio (GPM) foi maior em G-NA em comparação com G-N (0,69±0,33 vs. 0,40±0,29kg/dia). O G-NA resultou em um diâmetro maior de FD em D12 do que o G-N (11,6±2,7 vs. 9,3±1,5mm). Em conclusão, a CFA foi maior em novilhas Nelore, embora em ambas as raças essa contagem tenha sido altamente repetível durante a indução da puberdade. Novilhas mestiças apresentaram maior ECC e GPM com maior diâmetro de FD, indicando maior precocidade quando comparadas às novilhas Nelore.

Effect of rearing, season of birth, and father on labyrinth behaviour of dairy heifers

Objective of this study was to test the hypotheses that heifer's behaviour after 12 months (M) are impacted by rearing (feeding/housing) before weaning, seasons of birth, and father lineage. Fifty-one Holstein heifers (born in year seasons SB1, SB2, SB3, and SB4, originating from 4 fathers) were assigned to one of three rearing treatments: restricted suckling (RS), calf in pen with mother to 21st day, suck three times daily, then group pen (6 kg milk) to weaning; unrestricted suckling (US), calf in pen with foster cows (6 kg milk) to weaning; conventional rearing (CR), calf in the hutch to 56th day, then group pen to weaning (milk replacer 6 kg). After weaning at the 84th day, heifers were kept in groups with the same ration. The labyrinth behaviour was tested in the 12th and 19th M of the age. In the evaluation factors rearing and season of birth, groups US and SB3 solved the passage of the labyrinth the fastest (868.0 s, 857.4 s), the slowest were CR and SB1 (1148.2 s, 1257.5 s). The results show that the manner (housing/feeding) used to rear heifers and season of birth may impact their later labyrinth behaviour.(AU)

Effect of rearing, season of birth, and father on labyrinth behaviour of dairy heifers

Objective of this study was to test the hypotheses that heifer's behaviour after 12 months (M) are impacted by rearing (feeding/housing) before weaning, seasons of birth, and father lineage. Fifty-one Holstein heifers (born in year seasons SB1, SB2, SB3, and SB4, originating from 4 fathers) were assigned to one of three rearing treatments: restricted suckling (RS), calf in pen with mother to 21st day, suck three times daily, then group pen (6 kg milk) to weaning; unrestricted suckling (US), calf in pen with foster cows (6 kg milk) to weaning; conventional rearing (CR), calf in the hutch to 56th day, then group pen to weaning (milk replacer 6 kg). After weaning at the 84th day, heifers were kept in groups with the same ration. The labyrinth behaviour was tested in the 12th and 19th M of the age. In the evaluation factors rearing and season of birth, groups US and SB3 solved the passage of the labyrinth the fastest (868.0 s, 857.4 s), the slowest were CR and SB1 (1148.2 s, 1257.5 s). The results show that the manner (housing/feeding) used to rear heifers and season of birth may impact their later labyrinth behaviour.

Impacts of trace element supplementation on productive/reproductive postpartum performances of grazing dairy heifers from volcanic soils

This study has been designed to evaluate the effect of trace elements (TE) on the reproductive and productive performances of postpartum Holstein Friesian heifers, fed on pasture with origin on volcanic soils, poor in TE. Twenty-six heifers pregnant were divided into two groups: experimental (EG) and control (CG) groups (n=13, each group). For animals belonging to the EG, two intra-ruminal capsules with TE were administrated 60 days before partum, while in the CG, no boluses were administered. All animals' blood was collected weekly to assess progesterone levels by the ELFA technique for 11 weeks after partum. TE were evaluated on blood by AAS when the experience started, on the day of delivery, and after 60 days. Before calving, no statistical differences were observed between groups for the trace elements, although it has been noticed that heifers had deficiencies in Selenium, Copper, and Iodine. On the calving day and 60 days after, a statistical increase (p<0.05) in serum Copper and Selenium was observed in the animals belonging to the EG. For the other TE, no statistical differences were observed. Concerning reproductive characteristics, the EG, at five weeks postpartum, 70% of the cows were cyclic, while in the CG in the same period, 33% of animals showed signs of ovarian activity. At the level of productive parameters, no differences were observed between groups. The results obtained by the present study allow concluding that, under our experimental conditions, the administration of trace elements, in addition to reducing postpartum anestrus, increases the quality of the corpus luteum in the postpartum period of heifers.