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The aim was to compare reproductive outcomes of Nelore heifers submitted to timed AI (TAI) protocols, with 7 or 9 d of permanence of the intravaginal progesterone (P4) device and different times of prostaglandin F2α (PGF) administration, for first (n = 935) and second (n = 530) services. On Day −24, heifers without corpus luteum (CL) underwent a protocol for induction of ovulation. On Day 0, heifers received a P4 device (0.5 g) and 1.5 mg estradiol (E2) benzoate. In order for the TAI to be carried out on the same day, these treatments were performed 2 d later on the heifers treated with the 7-d protocol. Additionally, heifers received 0.5 mg PGF at different times, resulting in four experimental groups: 9dP4-PGFd9 (n = 365); 9dP4-PGFd7 (n = 369); 9dP4-PGFd0&9 (n = 364); 7dP4-PGFd0&7 (n = 367). These nomenclatures indicate for how many d the P4 device was kept and the specific day on which PGF was given. At P4 removal, all heifers received 0.5 mg E2 cypionate and 200 IU eCG, and TAI was performed 2 d later. Effects were considered significant when P ≤ 0.05 (superscript letters a,b) whereas a tendency was assumed when 0.05 < P ≤ 0.10. Groups 9dP4-PGFd0&9 and 7dP4-PGFd0&7 had lower percentage of heifers with CL at P4 removal. The diameter (mm) of the dominant follicle (DF) was affected by treatment at P4 removal (9dP4-PGFd9: 11.3 ± 0.3b; 9dP4-PGFd7: 11.8 ± 0.2ab; 9dP4-PGFd0&9: 12.6 ± 0.2a; 7dP4-PGFd0&7: 10.8 ± 0.2c) and at TAI (9dP4-PGFd9: 12.7 ± 0.3ab; 9dP4-PGFd7: 13.2 ± 0.2a; 9dP4-PGFd0&9: 13.4 ± 0.2a; 7dP4-PGFd0&7: 12.4 ± 0.3b). Expression of estrus (%) was affected by treatment (9dP4-PGFd9: 89.6a; 9dP4-PGFd7: 93.5a; 9dP4-PGFd0&9: 88.2ab; 7dP4-PGFd0&7: 85.6b). There were no differences among treatments for P/AI on Day 40 (30–35 d post AI), final P/AI (between Day 70 and parturition) and pregnancy loss (between Day 40 and final P/AI). When the permanence of the P4 device was compared, regardless of PGF treatments, 9-d protocols resulted in greater DF diameter at P4 removal and at TAI, and greater expression of estrus (90.4 vs. 85.6%) than the 7-d protocol. Despite that, the 7-d protocol resulted in greater P/AI on Day 40 (55.3 vs. 49.1%). In addition, there was an interaction between protocol duration and body weight, in which heavier heifers (≥ 307 kg) had greater P/AI when treated with the 7-d protocol, in comparison to 9-d. In conclusion, longer TAI protocols (9 d of P4 device duration) resulted in greater DF diameter and expression of estrus. However, the shorter TAI protocol (7 d of P4 device duration) produced greater P/AI on Day 40, particularly in heavier heifers. Within 9-d protocols, the additional dose of PGF on Day 0 or the anticipation of the PGF to Day 7 did not influence fertility. • 7 or 9 d of permanence of the P4 intravaginal device were evaluated in heifers. • PGF2α was administered at different times in E2/P4-based TAI protocols. • 9-d protocols resulted in larger DF and greater expression of estrus. • P/AI 30–35 d post AI was greater in heifers treated with 7-d protocol. • Heavier heifers had greater fertility when treated with the 7-d protocol. [ABSTRACT FROM AUTHOR]

In tropical beef cattle production systems, animals are commonly raised on pastures, exposing them to potential stressors. The end of gestation typically overlaps with a dry period characterized by limited food availability. Late gestation is pivotal for fetal development, making it an ideal scenario for inter‐ and transgenerational effects of the maternal gestational environment. Intergenerational effects occur due to exposure during gestation, impacting the development of the embryo and its future germline. Transgenerational effects, however, extend beyond direct exposure to the subsequent generations. The objective of the present study was to verify these effects on the post‐natal performance of zebu beef cattle. We extended the use of a reaction norm model to identify genetic variation in the animals' responses to transgenerational effects. The inter‐ and transgenerational effects were predominantly positive (−0.09% to 19.74%) for growth and reproductive traits, indicating improved animal performance on the phenotypic scale in more favourable maternal gestational environments. Additionally, these effects were more pronounced in the reproductive performance of females. On average, the ratio of direct additive genetic variances of the slope and intercept of the reaction norm ranged from 1.23% to 3.60% for direct and from 10.17% to 11.42% for maternal effects. Despite its relatively modest magnitude, this variation proved sufficient to prompt modifications in parameter estimates. The average percentage variation of direct heritability estimates ranged from 19.3% for scrotal circumference to 33.2% for yearling weight across the environmental descriptors evaluated. Genetic correlations between distant environments for the studied traits were generally high for direct effects and far from unity for maternal effects. Changes in EBV rankings of sires across different gestational environments were also observed. Due to the multifaceted nature of inter‐ and transgenerational effects of the maternal gestational environment on various traits of beef cattle raised under tropical pasture conditions, they should not be overlooked by producers and breeders. There were differences in the specific response of beef cattle to variations in the quality of the maternal gestational environment, which can be partially explained by transgenerational epigenetic inheritance. Adopting a reaction norm model to capture a portion of the additive variance induced by inter‐ or transgenerational effects could be an alternative for future research and animal genetic evaluations. [ABSTRACT FROM AUTHOR]

Copyright of Revista Foco (Interdisciplinary Studies Journal) is the property of Revista Foco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The objective of this experiment was to determine the feed intake pattern and feed sorting of 30 Nelore males finished in a feedlot fed diets based on three different sources of corn: whole crop silage (WCS), high moisture corn (HMC) or corn grain (CG). Feed intake pattern and feed sorting were determined on days 13, 27, 41, 55, 69, and 83 days after the beginning of the experiment in three times relative to feed delivery (4, 10, and 24 hours). Diets were size-separated using the three-screen (19, 8, and 4 mm) and a bottom pan to yield long (>19 mm), medium (8 mm), short (4 mm) and fine (0.05) of corn source on feed intake pattern. Regardless of the source of corn, animals expressed a preferential consumption or sorting for the long (104.01% for WCS, 126.99% for HMC, and 132.58% for CG) and medium (116.66% for WCS, 109.95% for HMC, and 135.14% for CG) particles of the diets, which may be a beneficial aspect in terms of rumen motility as well as maintaining rumen pH in an adequate range.

This study evaluated the influence of GnRH analogs (gonadorelin vs. buserelin) and doses (single vs. double) on LH release and ovulatory response in Bos indicus (Nelore) females on Day 7 of the estrous cycle. Cycling heifers and non-lactating cows were pre-synchronized: Day −10: progesterone (P4) implant insertion plus 2 mg of estradiol benzoate; Day −2: implant removal and 0.53 mg of cloprostenol sodium (PGF); Day 0: 25 μg of lecirelin (GnRH). Over four replicates, heifers (n = 57) and cows (n = 53) that ovulated to the GnRH treatment on Day 0, having a visible corpus luteum (CL) and a dominant follicle (DF) ≥ 8.5 mm, were allocated to receive the following GnRH treatments on Day 7: G-Single (100 μg of gonadorelin); G-Double (200 μg of gonadorelin); B-Single (10 μg of buserelin); and B-Double (20 μg of buserelin). At GnRH treatment, a P4 implant was inserted in heifers (0.5 g) and cows (1 g). Ultrasound examinations were done on Days −10, −2, 0, 2, 7, 9, 12, and 14 to evaluate DF diameter, ovulation and presence of CL. Blood samples were collected on Day 7 at 0, 2, and 4 h from GnRH treatment, to evaluate circulating P4 and LH concentrations. On Day 12, the P4 implant was removed, females received two PGF treatments (24 h apart), and 2 d later, 25 μg of GnRH was given to start the next replicate. In both heifers and cows, P4 concentrations were elevated on Day 7, and similar among groups (3.9 and 4.2 ng/mL, respectively). In heifers, buserelin induced greater LH peak (9.5 vs. 2.6 ng/mL; P < 0.01) and greater ovulation (88.9 [24/27] vs. 16.7% [5/30]; P < 0.01) than gonadorelin treatments, regardless of the dose. Similarly, in cows, buserelin induced greater LH peak than gonadorelin (9.9 vs. 4.9 ng/mL; P < 0.01). However, ovulation was only increased in cows from the B-Double group (90.9% [10/11]), whereas in the other groups the ovulatory response was similar (35.7% [15/42]). Regardless of treatment, heifers had similar P4 concentrations (P = 0.22), but smaller DF (P < 0.01) than cows on Day 7. Only in G-Double group the LH peak was lower (P = 0.05) in heifers than in cows, with no difference within other groups. In heifers, but not in cows, the single dose of buserelin resulted in high ovulatory response, equivalent to that produced by the double dose. In conclusion, in Bos indicus heifers and cows on Day 7 of the cycle, with elevated P4 concentrations, buserelin induced greater LH release and ovulatory response than gonadorelin treatments. Double doses increased the LH release, however, only resulted in greater ovulation in females treated with buserelin. Finally, although circulating P4 concentrations did not differ between parities, heifers were more likely to ovulate in response to a GnRH-induced LH peak than cows. • Buserelin induced greater LH release and ovulation than gonadorelin in Bos indicus. • Double doses increased LH release, but only double buserelin increased ovulation. • In heifers, but not cows, the single dose of buserelin resulted in high ovulation. • Heifers had similar circulating P4 but smaller dominant follicles than cows. • Heifers were more likely to ovulate after a GnRH-induced LH peak than cows. [ABSTRACT FROM AUTHOR]

The domestication of animals has rendered horns less necessary for survival. Moreover, the use of polled and disbudded animals is interesting in order to avoid injuries of animals and handlers, among other advantages. We therefore conducted a comparative economic analysis of different traditional disbudding techniques versus selective breeding for polledness in Nelore cattle, the main beef breed of tropical systems in Brazil. The cost to obtain animals without horns was estimated in three different scenarios: disbudding with hot iron, disbudding with caustic paste, and phenotypic selection for polled animals. Price quotations of the materials were obtained in different states of the country and averaged. An initial frequency of horned animals of 92.16% was obtained based on the records of the Brazilian Association of Zebu Breeders. Selective breeding was found to be the best cost-effective scenario. This result differs from intensive production systems of dairy cattle in which traditional disbudding continues to be the best cost-effective scenario. The main explanation is the lack of difference in the price of Nelore semen from polled and horned bulls. Phenotypic selection for polled animals is the best cost-effective method, and it is in accordance with welfare practices. Care should be taken regarding the intensive use of few polled breeding animals in order to avoid inbreeding depression in other traits. [ABSTRACT FROM AUTHOR]

BackgroundBeef tenderness is a complex trait of economic importance for the beef industry. Understanding the epigenetic mechanisms underlying this trait may help improve the accuracy of breeding programs. However, little is known about epigenetic effects on Bos taurus muscle and their implications in tenderness, and no studies have been conducted in Bos indicus.ResultsComparing methylation profile of Bos indicus skeletal muscle with contrasting beef tenderness at 14 days after slaughter, we identified differentially methylated cytosines and regions associated with this trait. Interestingly, muscle that became tender beef had higher levels of hypermethylation compared to the tough group. Enrichment analysis of predicted target genes suggested that differences in methylation between tender and tough beef may affect signal transduction pathways, among which G protein signaling was a key pathway. In addition, different methylation levels were found associated with expression levels of GNAS, PDE4B, EPCAM and EBF3 genes. The differentially methylated elements correlated with EBF3 and GNAS genes overlapped CpG islands and regulatory elements. GNAS, a complex imprinted gene, has a key role on G protein signaling pathways. Moreover, both G protein signaling pathway and the EBF3 gene regulate muscle homeostasis, relaxation, and muscle cell-specificity.ConclusionsWe present differentially methylated loci that may be of interest to decipher the epigenetic mechanisms affecting tenderness. Supported by the previous knowledge about regulatory elements and gene function, the methylation data suggests EBF3 and GNAS as potential candidate genes and G protein signaling as potential candidate pathway associated with beef tenderness via methylation.

Little is known about the performance, carcass, and meat traits of locally adapted cattle in Brazil. This study aimed to compare the growth, slaughter, and carcass traits as well as meat quality of two local breeds (Curraleiro Pé-Duro and Pantaneiro) with the Nelore breed. Fifteen 30-month-old steers of each breed were weighted (Curraleiro Pé-Duro = 264.80 kg; Nelore = 346.80 kg; Pantaneiro = 316.20 kg) and raised in a feedlot condition for 112 days, with measurements to assess growth and slaughter, visual and carcass and meat traits. Data were submitted to variance and multivariate analyses. Nelore and Curraleiro Pé-Duro had similar Gluteus medius depths. Pantaneiro and Curraleiro Pé-Duro were superior for leg compactness index (P < 0.05) and had higher eye muscle area than Nelore (P < 0.05). Although there was no difference in daily weight gain and slaughter weight between breeds, Curraleiro Pé-Duro had a lower initial weight (264.80 kg) when compared to Nelore (346.80 kg; P < 0.05). Nelore and Curraleiro Pé-Duro deposited more fat than Pantaneiro (P < 0.05), while Curraleiro Pé-Duro and Pantaneiro had more muscle than Nelore (P < 0.05), which also had more bone and a higher percentage of second-quality cuts (P < 0.05). Meat from Nelore also showed lower succulence than Pantaneiro (P < 0.05) and higher shear force than the other breeds (P < 0.05). Pantaneiro’s meat had the most capacity to retain water (P < 0.05), lower shear force (P < 0.05), and was more succulent (P < 0.05) when compared to the other breeds. Multivariate analysis showed that Pantaneiro, Curraleiro Pé-Duro, and Nelore breeds can be considered distinct in growth, carcass, and meat traits, with the local breeds showing superior meat traits. The local breeds Curraleiro Pé-Duro and Pantaneiro presented characteristics similar or better to those of the Nelore, proving to be animals with great productive potential and generate high meat quality under feedlot conditions. [ABSTRACT FROM AUTHOR]

Copyright of Revista Colombiana de Ciencia Animal - RECIA is the property of Revista Colombiana de Ciencia Animal - RECIA and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ionóforos são adicionados em dietas para animais de alta produção para aumentar o ganho de peso, melhorar a eficiência alimentar e modular a fermentação ruminal. No entanto, existem vários compostos diferentes que podem ser utilizados em dietas de animais. Este trabalho foi realizado com o objetivo de avaliar o desempenho animal, ingestão de ração, rendimento de carcaça e sanidade do epitélio ruminal de tourinhos Nelore terminados em confinamento e alimentados com dieta suplementada com narasina ou monensina ou uma combinação desses dois compostos. Anteriormente, os animais foram alimentados com dietas suplementadas com narasina. Foram utilizados 96 animais da raça Nelore com peso médio inicial de 334,1 ± 27,0 kg. Os animais foram bloqueados por peso (total de seis blocos) e alocados aleatoriamente em 24 baias (n = 4 animais por baia). Os tratamentos foram distribuídos aleatoriamente em cada baia de acordo, primeiramente, com a fase de recria e depois com a fase de confinamento: CONT+MONE, sem adição de aditivo na recria e monensina (27 ppm) no confinamento; CONT+NARA, sem adição de aditivo na recria e narasina (13 ppm) no confinamento; NARA+MONE, inclusão de narasina (13 ppm) na recria e monensina (27 ppm) no confinamento e NARA+NARA, narasin (13 ppm) na recria e no confinamento. Assim, houve arranjo fatorial 2 x 2, com seis repetições por tratamento. A inclusão de monensina e narasina não afetaram o desempenho animal, consumo de ração, rendimento de carcaça quente e sanidade ruminal. Os animais apresentaram alto ganho de peso (1,70 kg/dia), alto consumo de matéria seca (mais de 2,50% do peso corporal), alto rendimento de carcaça (próximo a 56,0%) e nenhum efeito adverso sobre o epitélio ruminal. Em conclusão, a narasina pode substituir a monensina em touros terminados em confinamento. A inclusão de narasin na fase de recria não melhora o desempenho subsequente do confinamento de bovinos Nelore, independentemente de terem consumido narasina ou monensina durante o confinamento por um período de 117 dias.

Abstract Background Beef tenderness is a complex trait of economic importance for the beef industry. Understanding the epigenetic mechanisms underlying this trait may help improve the accuracy of breeding programs. However, little is known about epigenetic effects on Bos taurus muscle and their implications in tenderness, and no studies have been conducted in Bos indicus. Results Comparing methylation profile of Bos indicus skeletal muscle with contrasting beef tenderness at 14 days after slaughter, we identified differentially methylated cytosines and regions associated with this trait. Interestingly, muscle that became tender beef had higher levels of hypermethylation compared to the tough group. Enrichment analysis of predicted target genes suggested that differences in methylation between tender and tough beef may affect signal transduction pathways, among which G protein signaling was a key pathway. In addition, different methylation levels were found associated with expression levels of GNAS, PDE4B, EPCAM and EBF3 genes. The differentially methylated elements correlated with EBF3 and GNAS genes overlapped CpG islands and regulatory elements. GNAS, a complex imprinted gene, has a key role on G protein signaling pathways. Moreover, both G protein signaling pathway and the EBF3 gene regulate muscle homeostasis, relaxation, and muscle cell-specificity. Conclusions We present differentially methylated loci that may be of interest to decipher the epigenetic mechanisms affecting tenderness. Supported by the previous knowledge about regulatory elements and gene function, the methylation data suggests EBF3 and GNAS as potential candidate genes and G protein signaling as potential candidate pathway associated with beef tenderness via methylation.

Objetivou-se avaliar neste trabalho, o efeito da Promixalicina para o controle de ecto e endoparasitas em bovinos Nelore ou anelorados em sistemas de pastejo, na região de Presidente Prudente/SP. Avaliou-se durante 28 dias após a ingestão do produto, a eficiência da promixalicina na diminuição de comportamentos de estresse por animais da raça Nelore. Sendo assim, foram utilizados ao total de 367 animais em diversas categorias, garrotes, novilhas e vacas prenhes. Avaliou-se com este estudo, o fornecimento da Promixalicina misturada ao Sal proteinado e ao concentrado, na dosagem de 5 gramas por animal por dia. A época da avaliação foi nos meses de setembro e outubro de 2021. Para efeito dos animais, após trazidos em área de piquete delimitado, foram avaliados após 10 minutos de descanso, o comportamento dos animais, mensurando os seguintes eventos de estresse: abano de cauda; abano de orelha; levante de perna; inquietação; cabeçada; coice e agressão. Houve redução significativa de 70% dos efeitos comportamentais dos animais. Não houve influência na ingestão de alimento pelo animal, bem como reduziu significativamente a OPG dos animais. A partir do presente estudo, pode-se inferir efeitos positivos e satisfatórios em 21 dias com o uso da Promixalicina na dieta de bovinos Nelore em pastagem, para o controle de endo e ectoparasitas.

The application of Fixed Time Artificial Insemination (FTAI) protocols has strongly boosted artificial insemination in Brazilian bovine herds. The control of the estrous cycle with protocols based on progesterone and estrogen involves synchronizing the emergence of a follicular wave, controlling the progesterone phase, and inducing ovulation in a synchronized manner. The increase in pregnancy rates starts with the preparation of the breeding season and the choice of protocols and females. Thereafter, based on the characteristics of the property and the lots of animals, small adjustments can be made to the hormonal protocols as needed. Finally, resynchronization can increase usability by allowing multiple inseminations within short periods. The search for new strategies is of paramount importance for the development of the FTAI protocol and the increase in final pregnancy rates. Thus, this review sought to highlight the main critical points and adjustments of the FTAI protocols and their applicability in the reproduction of beef cattle.

Growth data of 77,372 Nelore steers were used to estimate the selection effect on energy requirements considering two beef production systems: cow-calf and slaughter cycles. All the animals had measures from 120 days to 7 years old. The parameters necessary to evaluate the selection effect on energy requirements were obtained by random regression analysis using Legendre polynomials. The models included additive direct and maternal effects, and animal and maternal permanent environmental effects as random terms. Contemporary group and dam age at calving (linear and quadratic effect) were included as fixed effects, and orthogonal Legendre polynomials of animal age (cubic regression) were considered random covariables. The coefficients from the model M3353_5 were used to calculate the genetic gains necessary to predict the increase in phenotypes. The selection was simulated for body weight (BW) and weight gain (WG) at different ages and energy requirements were calculated using NRC equations. The cost of feed was calculated for a cow-calf and slaughter cycle of production considering a system of Brachiaria decumbens pasture without supplementation. In slaughter system, the selection for weight of 365 days of age is the best option. In cow-calf systems, the selection W120 is the best choice. [ABSTRACT FROM AUTHOR]

Fetal programming refers to the concept in which factors that affect the health and performance of the pregnant mother can have long-term effects on the offspring, through stimulation or injury during critical periods of gestation, which modulate fetal development and interfere with the performance of the offspring. The aim of this study was to evaluate the effect of early and conventional weaning on cytochrome C oxidation of 3,3'-Diaminobenzidine (DAB), which characterizes the functionality of the mitochondrial membrane, in subsequent male offspring generated by primiparous or multiparous females. Fifty-six Nelore males were evaluated, with an average initial age of 12.5 months. During the fetal development of these animals, their primiparous or multiparous mothers weaned calves at 150 or 240 days (early or conventional weaning, respectively). Thus, of the 56 animals used, 29 came from primiparous females, 14 from the early weaning group and 15 from conventional weaning. The other 27 animals came from multiparous females, 13 from the early weaning group and 14 from conventional weaning. Semen was collected at 12.5, 14.3, 15.5 and 17.3 months of age, using the electroejaculation technique. The functionality of the mitochondrial membrane was assessed by the ultracytochemical test of in situ cytochrome C oxidase activity. For this, an aliquot of 80 μL of semen incubated with 80 μL of DAB (diaminobenzidine - 1 mg/mL in Dulbecco's phosphate buffered saline - DPBS) at 37°C for one hour was used. After incubation, three smears were taken and fixed in 10% formaldehyde for 10 minutes. The slides were air-dried under protection from light and then evaluated under light microscopy at 1000x magnification. Two hundred cells were evaluated per sample and classified into four classes: DAB I: sperm with a fully stained midpiece, with practically all the mitochondria active, indicating high mitochondrial activity. DAB II: sperm with more than half of the mitochondria stained, indicating medium to high mitochondrial activity. DAB III: sperm with less than half of the mitochondria stained, indicating low mitochondrial activity. DAB IV: sperm with the middle part completely unstained, indicating no mitochondrial activity. The results were expressed as a percentage of each subpopulation in the sample. Statistical analyses were carried out using SAS software (Version 9.2; SAS Institute), analyzed by ANOVA using a mixed model (PROC MIXED). When a significant treatment effect was detected, the means were compared using Fisher's method of least significant difference for multiple comparisons. A significant difference was considered when P ≤ 0.05. There was no effect of weaning, mother, or interaction between weaning, mother and age (p > 0.05). However, there was an age effect for mitochondrial membrane potential (p < 0.01), with the data expressed as mean ± standard error of the mean: DAB I: 40.7c ± 3.6, 62.9b ± 2.6, 70.4a ± 2.3 and 70.3a ± 2.1; DAB II: 39.6a ± 2.8, 28.3b ±2.1, 21.6c ± 1.8 and 26.4bc ± 1.6; DAB III: 9.7a ± 0.9, 2.2b ± 0.7, 1.6b ± 0.6 and 1.1b ± 0.5; DAB IV: 13.6a ± 1.8, 6.6b ± 1.4, 6.5b ± 1.2 and 2.3c ± 1.1 when assessed at 12.5, 14.3, 15.5 and 17.3 months of age, respectively. The results of this study show that early or conventional weaning, using two classes of mothers, has no effect on the functionality of the mitochondrial membrane in the offspring of Nelore males. However, when evaluating the sperm of Nelore breed animals in the prepubertal and pubertal stages, it was possible to observe that as the animals get older, the functionality of the mitochondrial membrane becomes better. It can be concluded that there was no effect of fetal programming when using early and conventional weaning on the subsequent offspring of Nelore males sired by primiparous or multiparous mothers, but the functionality of the mitochondrial membrane becomes better as the Nelore males get older. [ABSTRACT FROM AUTHOR]

Copyright of Revista Brasileira de Reprodução Animal is the property of Revista Brasileira de Reproducao Animal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Brasileira de Reprodução Animal is the property of Revista Brasileira de Reproducao Animal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of the present study was to evaluate the efficiency of using in vitro fertilization to validate semen fertility for artificial insemination. Cryopreserved semen from ten bulls (five Nelore and five Brangus bulls) was evaluated using in vitro production of embryos (IVPE) and via fixed-time artificial insemination (FTAI). There was variation (p < 0.05) in the IVPE (20.9 to 53.7% of blastocyst production) and in the FTAI (42.0 to 56.0% of pregnant cows) results among the semen evaluated. According to the results, there was a positive correlation (rs = 0.8378; p = 0.0001) between the rate of blastocyst production (using IVPE) and the rate of pregnancy (using FTAI) using Nelore bull semen. Variation (p < 0.05) was also found using semen from Brangus bulls, in the rates of blastocyst production (36.5 to 47.0%) and pregnancy (45.6 to 52.2%) via FTAI. There was also a positive correlation (rs = 0.8786; p = 0.0001) between the rates of blastocyst production (IVPE) and pregnancy (FTAI) when using Brangus bull semen. According to the results, IVPE may be used in addition to conventional semen analysis to evaluate and validate the semen fertility of bulls for artificial insemination programs. [ABSTRACT FROM AUTHOR]

Summary: The aim of this study was to evaluate follicular development, morphological integrity, and antioxidant potential of preantral ovarian follicles from Bos taurus indicus females grown in vitro with alpha-lipoic acid. Ovaries (n = 24) of Bos taurus indicus (n = 12) females were collected during slaughter and fragmented. A randomly obtained fragment from each pair of ovaries was fixed in Bouin (non-cultivated control; D0). These fragments were intended for classical histology (morphology and evaluation of follicular growth), and a fragment from each pair of ovaries was frozen at −80°C (non-cultivated control; D0), and assigned for analysis of oxidative stress [thiobarbituric acid reactive substances (TBARS), nitroblue tetrazolium (NBT), and ferric reducing antioxidant power (FRAP)]. The remaining fragments were cultured in vitro for 6 (D6) or 12 (D12) days, containing only minimum essential medium (MEM) or MEM supplemented with alpha-lipoic acid (50, 100, or 250 ng/ml), on an extracellular matrix of agarose gel, in an oven at 38.5ºC. Every 2 days, 100% of the culture medium was replaced. Supplementation with 100 ng/ml was effective for maintaining follicular integrity after 6 days of culture (primordial: 51.28%; development: 36.88%; P < 0.0001). There was no difference (P > 0.05) between treatments compared with the non-cultivated control treatment (D0), using the NBT and TBARS assays. Therefore, supplementation of the in vitro culture medium of bovine preantral ovarian follicles with a concentration of 100 ng/ml of alpha-lipoic acid at 6 days of culture was effective for maintaining follicular integrity and, after 6 days, maintaining stable levels of reactive oxygen species. [ABSTRACT FROM AUTHOR]

• Growth models were used to calculate resilience indicators based on weight deviations. • Selection for higher performance influenced the resilience capability of heifers. • Bos indicus heifers are less affected by environmental challenges than Bos taurus. • LnVar showed moderate heritability and could be included in animal breeding programs. The aim of the study is to analyze different growth models for the estimation of resilience indicators and to assess the impacts of selection for yearling weight and breed on the resilience capacity of Nelore, Guzerá and Caracu heifers. Weight records of females (n = 38,937) from birth to the measurement of weight adjusted to 550 days of age (W550) were used to fit growth curves. Next, three resilience indicators were calculated based on weight deviations (residuals): natural logarithm of residual variance (LnVar), lag-one autocorrelation (r auto), and skewness of deviations. The means of the resilience indicators were compared between Nelore selection lines (NeC: selected based on the mean of the contemporary groups for W550; NeS: selected based on the highest selection differential for W550; and NeT: selected based on an index considering highest selection differential for W550 and lower residual feed intake) and breeds (Nelore, Guzerá, and Caracu). Additionally, the heritabilities of the resilience indicators were estimated, as well as the genetic correlations between these indicators and productive traits using blupf90+ program. The results indicated that selection for yearling weight had an impact on the resilience capacity of the animals, with NeS and NeT heifers exhibiting greater weight variability (mean LnVar: 6.09 ± 0.02 and 6.12 ± 0.02, respectively) but also the highest recovery rate (r auto : 0.04 ± 0.01 and 0.04 ± 0.01, respectively). Nelore heifers were the most resilient, with a fast recovery rate (r auto : 0.01 ± 0.05) and there was little influence of the environment on performance (skewness: 0.00 ± 0.01). Caracu was the breed most affected by environmental disturbances (LnVar: 6.46 ± 0.02), with inverse subsequent weight deviations (r auto : -0.12 ± 0.05). The heritabilities of the resilience indicators were low and moderate, with the highest estimates being observed for LnVar in the three breeds (0.05 ± 0.05 to 0.38 ± 0.07). LnVar and skewness showed moderate positive genetic correlations with W550 (0.29 ± 0.18 to 0.55 ± 0.12), while the genetic correlations of r auto with W550 were weak and negative (-0.19 ± 0.17 to -0.28 ± 0.20). Selection for yearling weight influenced the resilience capability to environmental challenges in heifers during the growth phase. The results reinforce the greater adaptation capacity of zebuine breeds (Bos indicus) to tropical environments when compared to taurine breeds (Bos taurus). LnVar showed enough genetic variability to be included in breeding programs for zebu breeds aiming selection for more resilient animals. [ABSTRACT FROM AUTHOR]

RESUMO A ultrassonografia é um exame complementar não invasivo ainda pouco utilizado na avaliação prepucial e sem descrições detalhadas da parte livre do pênis (PLP) de bovinos. Este estudo objetivou padronizar a ultrassonografia prepucial em bovinos hígidos da raça Nelore com um ano de idade e, para tanto, descreveu o aspecto da lâmina interna prepucial (LIP) e da PLP, determinando as principais janelas acústicas, a viabilidade da utilização de contraste no lúmen da cavidade prepucial (LCP) e o melhor posicionamento do animal para a realização do exame. O escaneamento foi realizado com os animais na posição quadrupedal e em decúbito lateral direito. Foram determinadas cinco janelas acústicas a partir do óstio até a identificação do recesso prepucial. Os escaneamentos foram realizados nos planos longitudinais, transversais e dorsais, antes e após a infiltração de solução fisiológica a 0,9% no LCP. Como conclusões, o exame ultrassonográfico permitiu identificar a LIP e a PLP em todos os planos e em todas as janelas acústicas propostas. O melhor ponto de referência é a identificação da glande. O posicionamento quadrupedal é mais adequado para a realização do exame e o uso de contraste é recomendado para delimitação topográfica das estruturas.

Foi avaliado o desempenho de touros Nelore em cobertura a campo por 4 dias com alta pressão de cios sincronizados, quanto a sua classificação andrológica por pontos(CAP) e teste de libido e testados em 4 tratamentos: T1 = CAP > 75 pontos e alta libido; T2 = CAP < 75 pontos e alta libido; T3 = CAP > 75 e baixa libido; T4 = CAP < 75 pontos e baixa libido. Os cios foram observados de 18 a 78 horas após a sincronização com os maiores percentuais registrados às 42 (40,1%) e às 54 (30,4%) horas. Foram registrados, em média, 24,62 ± 2,11 fêmeas em cio por lote com pico de 9,87 ± 1,55 fêmeas/touro/dia. O número médio de fêmeas gestante por touro foi de 9,25 ± 3,2. A taxa média de gestação foi de 33,33%, variando de 22,44 no T4 a 47,82% no T1 (p

We aimed to evaluate the morphological ovarian response to equine chorionic gonadotropin (eCG) prior to ovum pick-up (OPU) and its effects on the molecular phenotype of immature cumulus-oocyte complexes (COCs) from Nelore cow (Bos indicus) donors. To this end, 20 Nelore cows were distributed randomly into the synchronized-OPU (Sync-OPU) and synchronized plus stimulated-OPU (Sync + eCG-OPU) groups using a cross-over experimental design, as each cow was used in both treatments. On a random day of the estrus cycle (Day 0), all cows received an intravaginal implant with 1.0 g of progesterone and 2 mg IM of estradiol benzoate. On the morning of Day 3, only the Sync + eCG-OPU group received 400 IU of eCG IM. On the morning of Day 5, the P4 device was removed and OPU was conducted in both groups. Before OPU management, ultrasonography was used to identify and measure the follicles. The aspirated COCs were morphologically classified based on their cumulus cells (CC) layers and the texture of the ooplasm. The COCs classified as Grade 1, Grade 2, and Grade 3 were considered viable and used for the assessment of quality markers. Oocytes and CC were mechanically separated from pools of 25 immature COCs of the Sync-OPU and Sync + eCG-OPU groups immediately after the follicular aspiration and stored at −80 °C until RNA extraction. Relative quantification of several markers for oocyte quality was assessed by RT-qPCR. The eCG treatment increased the number of follicles sized 3.0–5.0 mm and >5.0 mm compared to that in Sync-OPU group. Moreover, the protocol with eCG improved the total number of oocytes and the number of viable oocytes, which is related to a high number of oocytes in Grade 3. Regarding the impact on transcriptional regulation in immature oocytes, the mRNA encoding BMP15 , SMAD1 , SMAD2 , SMAD3 , ACACA , and CPT1A was upregulated in Sync + eCG-OPU compared with the Sync-OPU group. Moreover, the relative mRNA abundance of CTSZ , a member of the cathepsins family functionally related to reduced oocyte competence, was lower in the Sync + eCG-OPU group than in the Sync-OPU group. In addition, CC CTSB , CTSS , and CTSK mRNA abundances were lower in the Sync + eCG-OPU group than in the Sync-OPU group. However, the relative abundance of AREG and EREG mRNA was higher in CC recovered from cows stimulated with eCG. In conclusion, the eCG approach addressing follicular stimulation in Nelore cows had a positive impact on early antral follicle development, followed by a positive morphological and molecular phenotype in bovine COCs. • Ovarian response to equine chorionic gonadotropin (eCG) before ovum pick-up (OPU). • ECG before OPU increased number of follicles between 3.0 and 5.0 and > 5.0 mm. • ECG before OPU increased total number of oocytes and viable oocytes. • ECG before OPU modulated mRNA abundance of several genes related to oocyte quality. [ABSTRACT FROM AUTHOR]

Objective. Evaluate the effects of supplementation with different protein sources (soybean meal and wheat bran with urea) on the productive performance, intake, digestibility, microbial protein synthesis, and metabolic profile of grazing beef heifers. Materials and methods. Were used twenty Nellore heifers at 8.5±0.06 months of age, with an initial average body weight of 241.5±4.71 kg. The animals were distributed in a completely randomized deseing with two treatments and ten replicates. Two protein sources in the supplements were evaluated: 1) Soybean meal (SBM), and 2) Soybean meal + Wheat bran + Urea (SBM+WB+U). Results. Crude protein (CP) and organic matter intakes were higher (p<0.05) for heifers from SBM compared with SBM+WB+U. The CP digestibility was increased (p<0.05) with SBM supplementation. Mean blood concentrations of glucose, cholesterol, serum urea nitrogen, and total proteins were not affected (p>0.10) by protein sources. In the same way, daily weight gain and final body weight were not influenced (p>0.10) by protein sources. Conclusions. The supplementation with soybean meal or wheat bran with urea in association with soybean meal in multiple supplements for grazing cattle provides similar productive and nutritional performance and metabolic profile in beef heifers. [ABSTRACT FROM AUTHOR]

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Background: the use of creep-feeding combined with the correct management of pastures has been one of the main tools of nutritional management in cattle. Objective: to evaluate the effects of supplementation with different protein regimes on the metabolic profile in grazing suckling male calves. Methods: fifty suckling Nellore male calves with average initial body weight (BW) of 114 ± 2.4 kg and 105 ± 3.0 days age were used and distributed in a completely randomized design in two treatments and 25 replicates. The protein regimens evaluated were low protein (LOW)-supplement with 150 g CP/kg DM and; High protein (HIGH) - supplement with 300 g CP/kg DM. The supplements were composed of soybean meal‚ cornmeal‚ wheat meal‚ mineral mixture‚ and molasses‚ and provided in amounts of 6 g/kg BW. The animals were subjected to 78 experimental days and kept in eight 5 hectares paddocks each‚ formed by Brachiaria decumbens and equipped with drinkers and feeders. All animals had unrestricted access to water. Blood samples were collected to quantify levels of urea‚ albumin‚ globulins‚ total protein‚ glucose‚ triglycerides‚ and insulinlike growth factor 1 (IGF-1). Globulin concentrations were calculated by the difference between total protein and albumin concentration. Results: no treatment effect was observed (p > 0.10) on concentrations of glucose (77.6 vs 81.6 mg/mL)‚ triglycerides (32.8 vs 39.2 mg/mL)‚ total proteins (6.52 vs 6.67 g/dL)‚ globulin (3.28 vs 3.25 g/dL) and IGF-1 (424 vs 441 nm/ mL); while the albumin (3.24 vs 3.42 g/dL) and SUN (10.2 vs 15.7 mg/dL) concentrations did show significant differences (p < 0.05)‚ being higher in the calves supplemented with higher level of crude protein. Conclusions: supplementation with 150 g CP/kg DM in the amount of 6 g/kg PC is recommended for lactating beef calves during the rainy season and rainy-dry transition. [ABSTRACT FROM AUTHOR]

Background: to ensure continuous calves' growth, the supply of supplements is necessary to impact the animals' tissue response. Objective: the aim of this study was to evaluate the effects of supplementation with different protein regimens on performance in suckling beef calves. Methods: fifty suckling Nellore calves with average initial body weight (BW) of 114 ± 2.4 kg and 105 ± 3.0 days age were used and distributed in a completely randomized design with two supplementation treatments: Low protein (LOW) and High protein (HIGH). The supplements were composed of soybean meal, cornmeal, wheat meal, mineral mixture, and molasses, containing 150 g CP/kg dry matter (DM) and 300 g CP/kg DM for LOW and HIGH respectively, and provided in amounts of 6 g/kg BW. The animals underwent 78 experimental days, and were kept in eight 5 hectares paddocks each, formed by Brachiaria decumbens and equipped with drinkers and feeders. For productive performance evaluation, all calves were weighed at the beginning and end of the experiment after 14 h for solids fasting. Also, on the 78th-day experimental carcass images were obtained by ultrasound between the 12th and 13th ribs over the longissimus muscle to measure the ribeye area and backfatthickness on the Longissimus muscle (FAT-L), and between the ischium and pubis to the backfat-thickness on the rump (FAT-R). Biopsies of Longissimus dorsi muscle were performed at 75 days to measure the number and diameter of muscle fibers. Results: no difference (p > 0.05) was observed for average daily gain (LOW = 0.98 vs HIGH = 1.00 kg/d) or final BW (LOW = 191 vs HIGH = 193 kg) throughout the experiment. Likewise, no effect (p > 0.05) of the amounts of protein supplementation was verified on ribeye area (LOW = 36.7 vs HIGH = 38.8 cm2), FAT-L (LOW = 1.38 vs HIGH = 1.54 mm), FAT-R (LOW = 2.06 vs HIGH = 2.30 mm), or number (LOW = 141 vs HIGH = 142) and diameter (LOW = 29.2 vs HIGH = 30.9) of muscle fibers. Conclusions: supplementation with 150 g CP/kg DM in the amount of 6 g/kg BW is recommended for suckling beef calves in grazing. [ABSTRACT FROM AUTHOR]

O presente estudo teve como objetivo avaliar o uso de dispositivos intravaginais contendo doses altas ou baixas de progesterona (P4) na taxa de prenhez de novilhas zebuínas submetidas à inseminação artificial em tempo fixo (IATF). Novilhas Bos indicus (Nelore) receberam, no dia 0, uma injeção im de 2 mg de benzoato de estradiol (BE) e, em seguida, foram divididas aleatoriamente em três grupos. Nos grupos 1 (n = 80) e 2 (n = 79) foi colocado um dispositivo intravaginal contendo 1,9 g (grupo 1) e 0,75 g ( grupo 2) de P4, enquanto que o grupo 3 (n = 76) não recebeu dispositivo. Os dispositivos intravaginais foram removidos no dia 8, juntamente com a aplicação im de uma dose luteolítica de cloprostenol. Metade dos animais de cada grupo recebeu adicionalmente um injeção im de 300 UI de eCG. Vinte e quatro horas depois, todos animais receberam uma segunda aplicação im de 1 mg de BE e foram inseminados 54-56 horas após a aplicação de cloprostenol. O diagnostico de prenhez foi realizado 40 dias após a IATF, por meio de ultrassonografia transretal. Os dados foram analisados ​​por regressão logística. As taxas de prenhez foram de 27,5% , 30,4% e 28,9% para os grupos 1, 2 e 3, respectivamente (P> 0,05). A injeção de eCG, bem como outras variáveis tais como escore corporal, fazenda e presença de CL no início dos tratamentos não influenciaram esse resultado. Em conclusão, o uso de dispositivos intravaginas contendo alto (1,9 g) ou baixo (0,75 g) teor de P4 resultou em semelhantes taxas de prenhez após IATF de novilhas Nelore púberes.

Objective. Evaluate the effects of supplementation with different protein sources (soybean meal and wheat bran with urea) on the productive performance, intake, digestibility, microbial protein synthesis, and metabolic profile of grazing beef heifers. Materials and methods. Were used twenty Nellore heifers at 8.5±0.06 months of age, with an initial average body weight of 241.5±4.71 kg. The animals were distributed in a completely randomized deseing with two treatments and ten replicates. Two protein sources in the supplements were evaluated: 1) Soybean meal (SBM), and 2) Soybean meal + Wheat bran + Urea (SBM+WB+U). Results. Crude protein (CP) and organic matter intakes were higher (p0.10) by protein sources. In the same way, daily weight gain and final body weight were not influenced (p>0.10) by protein sources. Conclusions. The supplementation with soybean meal or wheat bran with urea in association with soybean meal in multiple supplements for grazing cattle provides similar productive and nutritional performance and metabolic profile in beef heifers.

Abstract: The objective of this work was to evaluate the potential of the stable isotope technique to characterize beef cattle production systems in tropical conditions. For this, carbon and nitrogen stable isotopes were identified in non-defatted and defatted bovine muscles. A total of 45 cattle were evaluated in three production systems: pasture, conventional feedlot, and young beef bull feedlot (n = 15 per system). Samples from the Trapezius cervicis, Longissimus dorsi, and Semitendinosus muscles were collected to determine the isotopic composition of δ13C and δ15N. The isotopic data of the δ13C and δ15N of non-defatted and defatted muscles were subjected to the principal component analysis (PCA) and to the discriminant analysis (DA). The PCA allowed separating the three production systems based on the results obtained for the non-defatted and defatted muscles. A correct global classification rate of 100% and a cross-validation rate of 100% were obtained with the DA. The carbon and nitrogen isotopic ratio of non-defatted and defatted muscles allows for the precise identification of beef cattle production systems in tropical conditions.

The aim of this study was to identify SNPs located in mitochondrial DNA that are associated with reproductive traits in beef cows. A total of 1999 Nelore females genotyped with the high-density Illumina BovineHD BeadChip (Illumina Inc., San Diego, CA, USA) were used to study the association of mitochondrial DNA variants with reproductive traits using a single-step procedure. In a preliminary analysis, the present results indicate a small participation of the mitogenome in the expression of reproductive traits in beef cattle. However, possible difficulties related to the biological characteristics of mitochondrial DNA and its inheritance, genotyping, and annotation of the phenotypes studied may also explain the results. [ABSTRACT FROM AUTHOR]

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Copyright of Revista Brasileira de Reprodução Animal is the property of Revista Brasileira de Reproducao Animal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Although the second largest chromosome of the genome, the X chromosome is usually excluded from genome‐wide association studies (GWAS). Considering the presence and importance of genes on this chromosome that are involved in reproduction, the aim of this study was to evaluate the effect of its inclusion in GWAS on reproductive traits (scrotal circumference [SC], early pregnancy [P16] and age at first calving [AFC]) in a Nelore herd. Genotype data from 3,263 animals with the above‐mentioned phenotypes were used. The results showed an increase in the variances explained by the autosomal markers for all traits when the X chromosome was not included. For SC, there was an increase of more than 10% for the windows on chromosomes 2 and 6. For P16, the effect was increased by almost 20% for windows on chromosome 5. The same pattern was found for AFC, with an increase of more than 10% for the most important windows. The results indicate that the noninclusion of the X chromosome can overestimate the effects of autosomes on SC, P16 and AFC not only because of the additive effect of the X chromosome itself but also because of its epistatic effect on autosomal genes. [ABSTRACT FROM AUTHOR]

O objetivo do estudo foi avaliar o desempenho produtivo, produção de leite e os parâmetros da curva de lactação de vacas de corte e bezerros de três diferentes grupos genéticos no período pós-parto. Foram usadas 15 vacas paridas divididas em três grupos genéticos: cinco vacas ½Angus ½Nelore (F1), cinco ¼Angus ¼Nelore ½Tabapuã (F2) e cinco Nelore (NE). Avaliou-se a produção de leite, curva de lactação, peso corporal (PC), condição corporal (CC) e eficiência produtiva das vacas além do ganho de peso diário médio (GPDMB) e peso corporal no pós-parto e ao desmame (PCB) dos bezerros. As vacas F2 apresentaram maior PC comparado às F1 e NE que não diferiram entre si. O PCB do F2 e F1 não diferiram e, foram superiores aos NE dos 125 até 183 dias pós-parto. A CC das vacas F1 e F2 reduziu no período pós-parto, ao contrário das NE que mantiveram. Os bezerros mestiços tiveram melhor desempenho produtivo que o Nelore. A curva de lactação teve comportamento quadrático e parecido entre os grupos genéticos, assim como suas eficiências produtivas. As vacas F2 e F1 apresentaram maior produção de leite total e produção de leite diária em relação às vacas NE. Vacas mestiças, apesar das características produtivas superiores, tiveram eficiência produtiva parecida à raça Nelore, justificando o seu uso como matriz em sistemas de cruzamento com outras raças bovinas.

ABSTRACT: Cuts of muscle (biceps femoris) from three crossbreeds between the Nelore, Angus and Wagyu breeds of cattle (Crossbreed 1 (C1): ½ Angus and ½ Nelore; Crossbreed 2 (C2): ¾ Angus and ¼ Nelore; Crossbreed 3 (C3): ½ Wagyu, ¼ Nelore and ¼ Angus) were characterized by their chemical composition, pH, water activity and lipid oxidation. The cuts were submitted to wet brining in a 5 % NaCl concentration at 5 °C with either static brine (SB) or brine assisted with ultrasound (US). Samples of the treatments were taken after 30, 60, and 120 min of wet brining for later analysis. The experimental data were adjusted using the Peleg and Page models, and the Page template best described the experimental data. The crossbreeding did not affect the water and ash content; however, it significantly affected the levels of lipids and proteins. C3 presented higher fat content than C2, which, in turn, was higher than C1. C1 had higher protein content than C2, which had more protein than C3. When ultrasound was applied, crossbreeding influenced the water content and the water absorption rate during brining, which had the highest values for the highest protein content. The crossbreeding and ultrasound application also affected the NaCl content of the cuts. However, only ultrasound application increased the rate of NaCl absorption during wet brining. The results demonstrate that ultrasound accelerates the mass transfer in wet brining of the cuts of beef, regardless of the crossbreeds studied.

O objetivo com este estudo foi avaliar os resultados econômicos de confinamento de bovinos com três espaços disponíveis por animal (6, 12 e 24 m2 por animal). Para as simulações considerou-se confinamentos com capacidade estática de 5.000 animais por ciclo e dois ciclos de 86 dias por ano. Os dados de desempenho foram obtidos de 1.350 bovinos não castrados. O aumento no espaço elevou o custo fixo por animal. Os custos fixos e variáveis representaram 3% e 93% do custo operacional total, respectivamente. Dos custos variáveis, cerca de 70% foi utilizado para a compra de gado e 17% para a compra de alimentos. O lucro operacional por animal foi crescente com o aumento na disponibilidade de espaço (R$ 80,90; R$ 102,00 e R$ 109,00 para 6, 12 e 24 m2 por animal, respectivamente). Os três sistemas de confinamento recuperaram o investimento inicial e apresentaram valor presente líquido positivo. Além disso, as taxas internas de retorno foram de 22%, 27% e 25%, e as probabilidades de perdas financeiras foram de 33%, 29% e 26% para as dimensões de 6, 12 e 24 m2 por animal, respectivamente. Portanto, maior concessão de espaço nos currais de confinamento melhora a rentabilidade e reduz o risco de perda financeira.

Knowledge of animal behavior can be indicative of the well-being, health, productivity, and reproduction of animals. The use of accelerometers to classify and predict animal behavior can be a tool for continuous animal monitoring. Therefore, the aim of this study was to provide strategies for predicting more and less frequent beef cattle grazing behaviors. The behavior activities observed were grazing, ruminating, idle, water consumption frequency (WCF), feeding (supplementation) and walking. Three Machine Learning algorithms: Random Forest (RF), Support Vector Machine (SVM) and Naïve Bayes Classifier (NBC) and two resample methods: under and over-sampling, were tested. Overall accuracy was higher for RF models trained with the over-sampled dataset. The greatest sensitivity (0.808) for the less frequent behavior (WCF) was observed in the RF algorithm trained with the under-sampled data. The SVM models only performed efficiently when classifying the most frequent behavior (idle). The greatest predictor in the NBC algorithm was for ruminating behavior, with the over-sampled training dataset. The results showed that the behaviors of the studied animals were classified with high accuracy and specificity when the RF algorithm trained with the resampling methods was used. Resampling training datasets is a strategy to be considered, especially when less frequent behaviors are of interest.

This study aimed to validate a 7 d progesterone (P4)-based fixed-time AI (FTAI) protocol for Bos indicus cattle by comparing to 8 and 9 d-type protocols. The first study compared 7 vs. 8 d protocols in Nelore heifers (Exp. 1.1; n = 742) and cows (Exp. 1.2; n = 2488), and the second study compared 7 vs. 9 d protocols in cows (Exp. 2; n = 1343). On experimental Day −10 and Day −11 the 8 and 9 d groups received an intravaginal P4 implant, 2.0 mg estradiol benzoate (EB) and 0.5 mg cloprostenol sodium (PGF). On Day −9 the 7 d group received the same treatments (P4, EB, and PGF). Then, on Day −2 all groups had the P4 implants removed, and PGF, 0.6 mg estradiol cypionate, and 300 IU equine chorionic gonadotropin (eCG) was administered. Fixed-time AI was performed 48 h later (Day 0) and 8.4 mg buserelin acetate (GnRH) was administered to 7d-G, 8d-G and 9d-G groups, whereas 7d-0, 8d-0 and 9d-0 groups did not receive GnRH at AI. Estrus was detected using tail-chalk between Day −2 and Day 0. Pregnancy per AI (P/AI) was evaluated by ultrasound 30 d after AI. Effects were considered significant when P ≤ 0.05, whereas a tendency was designated when P ≤ 0.10 and P > 0.05. In heifers (Exp. 1.1), incidence of estrus was similar regardless of protocol length (7 or 8 d). There was no independent treatment effect on P/AI or interaction between protocol length and GnRH at AI for P/AI (7d-0: 46.9, 7d-G: 51.4, 8d-0: 47.7, and 8d-G: 43.6%). Heifers in estrus had greater P/AI, and GnRH had no additional effect. More cows (Exp. 1.2) from the 8 d protocol were in estrus than cows submitted to the 7 d protocol. Additionally, despite no interaction between protocol length and GnRH on P/AI (7d-0: 55.9, 7d-G: 60.9, 8d-0: 56.2, and 8d-G: 60.8%), GnRH at AI increased P/AI. There was no interaction between estrus and GnRH, but cows displaying estrus had greater P/AI. Cows not expressing estrus tended (P = 0.06) to have greater P/AI when receiving GnRH. In Exp. 2, more 9 d cows were in estrus than 7 d cows. Protocol length did not affect P/AI but tended (P = 0.08) to interact with GnRH (7d-G had greater P/AI [57.9%] than 7d-0 [47.6%], but 9d-0 [54.6%] and 9d-G [55.4%] were not different from other groups). Moreover, GnRH increased P/AI only for the 7 d protocol. No interaction between estrus and GnRH was detected but estrus improved P/AI, and GnRH tended (P = 0.09) to improve P/AI of cows in estrus. In conclusion, despite longer protocols being more conducive to expression of estrus, there were no detectable effects of protocol length on P/AI. In addition, GnRH at FTAI may improve fertility in cows, particularly when cows are treated with shorter protocols. • A 7 d progesterone (P4)-based fixed-time AI (FTAI) protocol for Bos indicus cattle was compared to 8 and 9 d-type protocols. • Incidence of estrus in response to the protocols and impact of treatment with GnRH at AI on pregnancy per AI were evaluated. • Protocol length did not affect P/AI, but estrus increased P/AI. Treatment with GnRH at AI increased P/AI in cows. [ABSTRACT FROM AUTHOR]

This study evaluated the association between plasma anti‐Mullerian hormone (AMH) concentration and fertility in Nelore (Bos indicus) heifers submitted to timed artificial insemination (TAI). At the onset of the synchronization protocol, heifers (n = 289) received a subcutaneous P4 ear implant (3 mg) and 2 mg of oestradiol benzoate. Eight days later, the P4 implant was removed and 0.5 mg of oestradiol cypionate, prostaglandin (0.265 mg, i.m.) and equine chorionic gonadotropin (300 UI, i.m.) was administered, and TAI was performed 48 hr after ear implant removal. Ovarian ultrasound evaluations were performed to measure number of ovarian follicles, dominant follicle size and ovulation response. Pregnancy diagnosis was performed by ultrasound 30 days after AI. Heifers with greater circulating AMH had more antral follicles, a smaller dominant follicle near timed ovulation and lower ovulation response to the timed AI protocol compared to heifers with lower circulating AMH. Although AMH and pregnancy outcome had a quadratic‐shaped pattern, AMH was not significantly associated with fertility. In conclusion, heifers with lower AMH had larger follicles towards the end of the synchronization protocol and greater ovulation responses, whereas greater circulating AMH was unrelated to conception success. [ABSTRACT FROM AUTHOR]

Background: Rehydration of grains, such as corn and sorghum, is used to increase nutrient absorption. However, the effect of this practice on meat quality is poorly understood. Objective: To evaluate the effects of type of grain and processing on the meat quality of Nellore steers in a feedlot. Methods: Twenty-four non-castrated Nellore steers (270 ± 53 kg initial body weight) were distributed in a completely randomized 2×2 factorial design, with six replicates. The first factor was cereal type (corn or sorghum), and the second was the grain processing (dry or rehydrated and ensiled). The diets were composed of 28.44% corn silage and 71.56% concentrate. Sixty days before the beginning of the experiment, corn and sorghum grains were rehydrated and ensiled. The animals were slaughtered after 140 days of confinement. Meat quality analyses were determined in samples of fresh and aged meat (7 days) from the Longissimus lumborum muscle. Results: no difference between treatments was observed for carcass pH and L* (lightness), a* (redness), and b* (yellowness) values, shear force, thawing and cooking losses, and chemical composition of meat (p>0.05). The b* (yellowness) value of subcutaneous fat was higher in steers fed corn, regardless of grain processing (p=0.03). Sarcomere length was higher in aged meat of steers fed sorghum, regardless of processing method (p=0.01). Conclusions: the grain processing method does not affect beef quality; however, grain type can affect subcutaneous fat color and sarcomere length of aged beef. [ABSTRACT FROM AUTHOR]

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The aim of this study was to evaluate circulating progesterone concentration (P4), LH pulsatility and ovarian follicular dynamics in Nelore (B. indicus) and Holstein (B. taurus) heifers under high (HDMI) and low (LDMI) dry matter/energy intakes. In addition, the effects of dry matter/energy intake and breed on hepatic expression of six genes associated with P4 metabolism (AKR1C4, AKR1D1, CYP3A4, CYP2C19, SRD5A1, and SRD5A3) was evaluated. Heifers received an intravaginal P4 device (1 g), 2 mg of estradiol benzoate (EB) i.m. and 500 μg of PGF 2α at the begging of the synchronization protocol (D0). Eight days later, the P4 device was removed and all heifers received 1 mg of EB 24h later. Regardless of dry matter/energy intake, the number of recruited follicles was greater in Nelore than in Holstein heifers. In contrast, the maximum diameter of the dominant follicle was greater in Holstein than in Nelore heifers. Circulating P4 concentrations were greater in Nelore than in Holstein from D2 to D9, and in heifers receiving LDMI than those receiving HDMI from D1 to D8 of hormonal protocol. In addition, Holstein heifers had greater LH pulsatility and area under the curve of LH peaks compared to Nelore heifers. However, no effects were observed for LH values between feed intake levels. Interestingly, Holstein heifers had higher expression of SRD5A1, AKR1C4, AKR1D1 than Nelore heifers; whereas, for Nelore heifers, only the expression of CYP3A4 was higher compared to Holstein heifers. In conclusion, there are important differences in the follicular dynamics, circulating P4 and LH pulsatility concentrations that need to be considered during synchronization protocols for Nelore and Holstein breeds. More importantly, these differences appear to be at least partially modulated by the level of feed intake and the contrasting enzyme system in the liver involved with P4 metabolism between these cattle breeds. • Circulating P4 concentration is modulated by level of feed intake and the contrasting enzyme system in the liver in heifers. • Gene expression associated with progesterone catabolism in the liver is different between Holstein and Nelore heifers. • B. taurus presented a greater number of LH peaks compared to B. indicus heifers. [ABSTRACT FROM AUTHOR]

Background: Rumen microorganisms have developed a series of complex interactions, representing one of the best examples of symbiosis between microorganisms in nature. Conventional taxonomic methods based on culture techniques are being replaced by molecular techniques that are faster and more accurate. Objective: To characterize rumen bacterial diversity of Nellore steers grazing on tropical pastures by sequencing the 16S rRNA gene using Illumina sequencing. Methods: Three rumen-cannulated Nellore steers were used. The liquid and solid fractions of the rumen contents were processed to extract metagenomic DNA, and the V1 and V2 hypervariable regions of the 16S rRNA gene were sequenced using Illumina sequencing. Results: A total of 11,407,000 reads of adequate quality were generated, and 812 operational taxonomic units (OTUs) were found at the species level. Twenty-seven phyla were identified, and the predominant phyla were Firmicutes (23%), Bacteroidetes (14%), Proteobacteria (10%), Spirochaetes (9%), Fibrobacteres (7%), Tenericutes (5%), and Actinobacteria (2%), which represented 70% of the total phyla identified in the rumen content. Conclusion: Rumen environment in grazing Nellore steers showed high bacterial diversity, with Firmicutes, Bacteroidetes, Proteobacteria, Spirochaetes, and Fibrobacteres as the predominant phyla. [ABSTRACT FROM AUTHOR]

A neosporose é uma doença parasitária ocasionada pelo protozoário intracelular obrigatório Neospora caninum, responsável por quadros de abortos em bovinos em várias regiões do país. A principal forma de transmissão entre os bovinos é a via vertical ou transplacentária com abortos prevalentes entre 3 a 6 meses de gestação. Este trabalho teve como objetivo pesquisar a presença de anticorpos anti-N.caninum em fêmeas e fetos bovinos da raça Nelore (Bos indicus), do município de Nossa Senhora do Livramento-MT. Durante o abate dos animais foram coletadas amostras de sangue de 489 fêmeas e de 128 fetos acima de três meses de gestação. A pesquisa de anticorpos anti N. caninum nas fêmeas e fetos foi determinada pela Reação de Imunofluorescência Indireta (RIFI). A ocorrência foi de 2,45% para as fêmeas e de 3,91% para os fetos.

This study evaluated the pregnancy rate in Nelore cows (Bos indicus) that were subjected to fixed-time artificial insemination (FTAI) using different protocols consisting of injectable progesterone (P4) or an intravaginal device (impregnated with P4). Multiparous cows 72-84 months in age, 30-45 days postpartum, were selected on the basis of the absence of a corpus luteum (CL) and follicles < 8 mm after transrectal palpation and ultrasound examinations. On a random day of the estrus cycle (D0), the selected animals (n = 135) were randomly assigned to one of three experimental groups (n = 45 each). Group I (injectable P4/FTAI 36 hours) received 250 mg of injectable P4 and 2 mg EB on D0; on D7, they received 500 µg of cloprostenol; on D8, 300 IU of eCG and 1 mg of EB were administered; and finally, FTAI was performed 36 hours after the application of EB. Group II (injectable P4/FTAI 48 hours) received the same protocol as Group I, except that the FTAI was performed 48 hours after ovulation induction. The animals of Group III (Control/CIDR) received a conventional protocol for FTAI using an intravaginal device (D0: P4 and 2 mg EB; D8: device removal, 500 µg cloprostenol, 300 IU eCG, 1 mg EB; and FTAI performed 48 hours after removal of the device). The results showed that cows synchronized with the conventional protocol for FTAI (Control/CIDR) had a higher pregnancy rate (60 %, 27/45) than those synchronized with an injectable P4/FTAI 36 hours (33.33 %; 15/45, P = 0.010). However, the group receiving injectable P4 group/FTAI 48 hours had a similar pregnancy rate (48.9 %; 22/45; P = 0.290) when compared to both the group receiving the conventional protocol and that receiving injectable P4/FTAI 36 hours (P = 0.134). Although the injectable P4 may affect pregnancy rate with the FTAI performed in 36 hours, we found similar pregnancy rates from cows inseminated 48 hours after induction ovulation, considering injectable or intravaginal P4. Therefore, we suggest that injectable P4 represents an alternative source of progesterone for synchronization of cattle for FTAI.

The expansion of the biodiesel industry has created opportunities for crude glycerol use in beef cattle diets. The objective of this study was to determine the effects of substituting sorghum grain with crude glycerol on dry matter intake (DMI), weight gain and feed intake pattern of 28 non-castrated Nelore males with initial body weight (BW) of 441 ± 40.2 kg and 21.5 ± 0.5 months of age housed in individual or collective pens. The experiment lasted 98 days (June 29 through October 5, 2015), with a 14 day-period of adaptation and 84 days for data collection. Crude glycerol was included at 15% of the ration dry matter as a replacement for sorghum grain. Orts were collected and weighed daily, and DMI was calculated by difference between feed offered and feed refused. Feed intake pattern was determined every two weeks after the beginning of the study in three intervals relative to feed delivery (0-4, 4-10, and 10-24 hours post-feeding). Animals' BW was obtained on days 1, 13, 27, 41, 55, 69, and 83 days of the trial after a 12-hour solid fasting. Crude glycerol did not alter (P>0.05) DMI, weight gain, hot carcass weight and dressing percentage compared with the control diet. A treatment × days of experiment response (P<0.05) occurred due to a decreased DMI in animals fed crude glycerol during the first 14 days of the trial. Crude glycerol-fed animals decreased (P<0.05) the neutral detergent fiber (NDF) intake pattern in individual and collective pens. Crude glycerol can be recommended at 15% of the total DM ration as a sorghum grain replacement in diets fed to Nelore animals finished in feedlot. [ABSTRACT FROM AUTHOR]

The expansion of the biodiesel industry has created opportunities for crude glycerol use in beef cattle diets. The objective of this study was to determine the effects of substituting sorghum grain with crude glycerol on dry matter intake (DMI), weight gain and feed intake pattern of 28 non-castrated Nelore males with initial body weight (BW) of 441 ± 40.2 kg and 21.5 ± 0.5 months of age housed in individual or collective pens. The experiment lasted 98 days (June 29 through October 5, 2015), with a 14 day-period of adaptation and 84 days for data collection. Crude glycerol was included at 15% of the ration dry matter as a replacement for sorghum grain. Orts were collected and weighed daily, and DMI was calculated by difference between feed offered and feed refused. Feed intake pattern was determined every two weeks after the beginning of the study in three intervals relative to feed delivery (0-4, 4-10, and 10-24 hours post-feeding). Animals' BW was obtained on days 1, 13, 27, 41, 55, 69, and 83 days of the trial after a 12-hour solid fasting. Crude glycerol did not alter (P>0.05) DMI, weight gain, hot carcass weight and dressing percentage compared with the control diet. A treatment × days of experiment response (P<0.05) occurred due to a decreased DMI in animals fed crude glycerol during the first 14 days of the trial. Crude glycerol-fed animals decreased (P<0.05) the neutral detergent fiber (NDF) intake pattern in individual and collective pens. Crude glycerol can be recommended at 15% of the total DM ration as a sorghum grain replacement in diets fed to Nelore animals finished in feedlot. [ABSTRACT FROM AUTHOR]