Fibra solúvel e amido como fontes de carboidratos para terminação de novilhos em confinamento

Avaliou-se o efeito da utilização de duas fontes de carboidratos solúveis, amido ou fibra solúvel em detergente neutro, associadas a dois níveis de FDN, sobre o desempenho de novilhos de corte em confinamento na fase de terminação. Foram confinados 24 novilhos ½ Angus x ½ Nelore, com idade inicial de 18 meses e peso de 329 ± 24 kg. As quatro dietas foram calculadas para fornecer nível de PB suficiente para ganho diário de 1,4 kg. As dietas foram constituídas de 40% de silagem de milho e 60% de concentrado (grão de milho, polpa cítrica e casca de soja), além de minerais e uréia, arranjados de forma a promover nível alto de amido associado a dois níveis de FDN (48 e 39%) ou nível alto de fibra solúvel associado aos dois níveis de FDN. Observou-se que os animais alimentados com a dieta com maior nível de polpa cítrica (45%), com baixos teores de fibra solúvel e FDN, apresentaram consumo reduzido e, conseqüentemente, baixo ganho de peso e pior conversão alimentar. Entre as dietas com maior nível de FDN, verificou-se que os animais alimentados com fibra solúvel apresentaram o melhor ganho de peso (1,435 vs 1,262 kg/dia) e a melhor conversão alimentar (7,494 vs 8,651), mas não diferiram daqueles do tratamento com amido e baixo teor de FDN. Os resultados demonstraram que é possível alterar o desempenho animal manipulando a fonte e a concentração dos carboidratos solúveis.

Desempenho de bezerros da raça Nelore e cruzados desmamados recebendo concentrado em pastagem adubada de Cynodon dactylon cv. Coastcross

Em três anos de pesquisa, avaliou-se o desempenho de bezerros desmamados de quatro grupos genéticos (Nelore; Canchim × Nelore; Angus × Nelore; e Simental × Nelore) em pastagem de Cynodon dactylon, cv. Coastcross, adubada, sob manejo rotacionado, recebendo mistura mineral ou concentrado. O concentrado foi fornecido na quantidade de 3 kg/animal/dia e continha 18,8% de proteína bruta e 81,5% de nutrientes digestíveis totais na matéria seca. A quantidade de forragem disponível diferiu com a utilização de mistura mineral e concentrado (2.961 kg e 3.383 kg de matéria seca (MS) por hectare, respectivamente). A oferta de MS/animal/dia foi 9,9 kg/dia (3,9% PV) para mistura mineral e 9,0 kg/dia (3,3% PV) para concentrado. A forragem disponível possuía, na matéria seca, 13,6% de proteína bruta, 79,8% de fibra em detergente neutro; 62,3% de digestibilidade in vitro da matéria seca, 3,9 g/kg de cálcio, 2,0 g/kg magnésio, 2,5 g/kg de fósforo, 22,7 g/kg de potássio, 2,8 g/kg de enxofre, 9,9 mg/kg de cobre, 22,5 mg/kg de zinco, 98 mg/kg de manganês e 188 mg/kg de ferro. Foram observadas interações grupo genético × suplementação e ano × suplementação para ganho diário de peso e taxa de lotação das pastagens e ciclo de pastejo × suplementação para a taxa de lotação. O ganho diário de peso nos animais Nelore, Canchim × Nelore, Angus × Nelore e Simental × Nelore criados com suplementação do pasto com mistura mineral foi de 0,48; 0,63; 0,68 e 0,50 kg, enquanto naqueles que receberam concentrado foi de 0,87; 0,95; 0,99 e 0,95 kg, respectivamente. As médias estimadas das taxas de lotação das pastagens foram 6,1 para todos os grupos genéticos que receberam mistura mineral e 7,5; 7,6; 8,8 e 9,0 unidades animais/ha para os grupos genéticos Nelore, Canchim × Nelore, Angus × Nelore e Simental × Nelore que receberam concentrado, respectivamente. O grupo genético influencia o desempenho de bovinos em pastagem de capim-coastcross e interage com a suplementação com concentrado.

Quality of the forage apparently consumed by beef calves in natural grassland under fertilization and oversown with cool season forage species

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effects of sire breed-grazing system and environmental parameters on the behaviour of beef calves just after birth

Effects of sire breed-grazing system and environmental factors on the first activities of high grade Nellore and crossbred Canchim x Nellore, Angus x Nellore, and Simmental x Nellore calves raised in intensive production systems and high grade Nellore calves raised in an extensive production system, after birth, were studied. During 2 years, 185 calves were observed from birth until the end of first suckling, and the following variables were estimated: duration of maternal attention (cow to calf) during the first 15 min after calving, latency to first attempt to stand up, latency to stand up, latency to first suckling, duration of first suckling and the interval from standing to suckling. Data were analyzed by least squares methods, with models that included fixed effects of year and time of the year of birth (March-April (early autumn) and May-June (late autumn)), sire breed-grazing system (Sy), sex of calf (Se), category of cow (primiparous and pluriparous), time of birth, Sy x Se, year x Sy and year x time of the year interactions and the covariates weight of calf, rainfall, air temperature and relative humidity in the day of birth. Calves born from 6:00 to 8:00 h presented the longest latencies to first stand up (40.3 +/- 5.1 min) and the shortest occur from 14:00 to 16:00 h (15.8 +/- 2.7 min) (P < 0.01). Primiparous cows provided longer attention toward the calf in the first 15 min after birth than pluriparous cows (13.0 +/- 0.7 min versus 11.1 +/- 0.5 min; P < 0.05). This attention was also shorter in earlier autumn (11.0 +/- 0.5 min) and longer in late autumn (13.1 +/- 0.8 min) (P < 0.05). Relative to sire breed-grazing system, Nellore calves raised intensively did take longer to stand and to suckle after birth as compared to crossbred calves also raised intensively (P < 0.01). However, grazing system did not affect (P > 0.05) any behaviour variable studied. As regard to sex differences, female calves did take less (P < 0.01) time to suckle after standing than male calves. Results showed that even purebred or crossbred Bos indicus calves in subtropical environmental need extra care when born on rainy days, especially during the first hours of the day. (C) 2006 Elsevier B.V. All rights reserved.

Ovarian follicle diameter at timed insemination and estrous response influence likelihood of ovulation and pregnancy after estrous synchronization with progesterone or progestin-based protocols in suckled Bos indicus cows

The objectives of the present study were to evaluate factors associated with estrous synchronization responses and pregnancy per insemination (P/AI) in Bos indicus beef cows submitted to progesterone-based fixed-time artificial insemination (FTAI) protocols. A total of 2388 cows (1869 Nellore and 519 crossbred Nellore x Angus) from 10 commercial farms were evaluated to determine the relationships among breed, body condition score (BCS) on the first day of the FTAI protocol, the occurrence of estrus between progesterone device removal and FTAI and diameter of largest ovarian follicle (LF) at FTAI on estrous synchronization responses and P/AI. Cows (n=412 primiparous; 1976 multiparous) received an intravaginal device containing progesterone or an ear implant containing norgestomet (a progestin), and an injection of estradiol at the beginning of the estrous synchronization protocol. Body condition was scored using a 1-5 scale on the first day of the FTAI protocol and at 30-60 days postpartum. Females received 300IU of equine chorionic gonadotropin (eCG) and PGF(2 alpha) on the day the progesterone device/implant was removed and were inseminated 48-60h later. At insemination, cows (n=2388) were submitted to an ultrasonographic exam to determine the diameter of the LF. Follicles were classified into four categories based on mean and standard deviation (SD) of the LF (LF1 = two SD below the mean; LF2 = mean minus one SD; LF3 = mean plus one SD; LF4 = two SD above the mean). Ovulation rate was determined in a subset of cows (n=813) by three consecutive ultrasonographic exams: (1) at time of progesterone device/implant removal, (2) at time of FTAI and (3) 48 h after FTAI. Ovulation was defined as the disappearance of a large follicle (>= 8.0 mm) that was previously recorded. Estrus was determined in a subset of the cows (n = 445) by the activation of a detection of estrous patch placed on the tail head on the day of progesterone device/implant removal. Pregnancy was diagnosed 30 days after FTAI. Pregnancy was influenced (P = 0.001) by follicle diameter [LF1 = 27.5% (81/295), LF2 = 46.6% (328/705), LF3 = 57.9% (647/1118), LF4 = 63.3% (171/270)] and the occurrence of estrus [estrus = 67.7% (174/257) and no estrus = 36.2% (68/188)]. Follicle diameter at FTAI influenced ovulation rate [LF1 = 42.5% (34/80), LF2 = 73.9% (161/218), LF3 = 95.8% (407/425), LF4 = 97.8% (88/90)], the occurrence of estrus [LF1 = 54.8% (51/93), LF2 = 33.6% (43/128), LF3 = 68.9% (126/183), LF4 = 90.2% (37/41)] and P/AI among cows that had ovulations [LF1 =32.4% (11/34), LF2 = 50.3% (81/161), LF3 = 60.0% (244/407), LF4 = 68.2% (60/88)]. Improving estrous responses between progesterone device withdrawal and FTAI and increasing the diameter of the LF at FTAI may be important aspects to achieve improved estrous synchronization responses and P/AI following progesterone/progestin and estradiol based FTAI protocols in suckled Bos indicus cows. (C) 2010 Elsevier B.V. All rights reserved.

Influence of the breed of bull (Bos taurus indicus vs. Bos taurus taurus) and the breed of cow (Bos taurus indicus, Bos taurus taurus and crossbred) on the resistance of bovine embryos to heat

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Copy number variation of individual cattle genomes using next-generation sequencing

Copy number variations (CNVs) affect a wide range of phenotypic traits; however, CNVs in or near segmental duplication regions are often intractable. Using a read depth approach based on next-generation sequencing, we examined genome-wide copy number differences among five taurine (three Angus, one Holstein, and one Hereford) and one indicine (Nelore) cattle. Within mapped chromosomal sequence, we identified 1265 CNV regions comprising similar to 55.6-Mbp sequence-476 of which (similar to 38%) have not previously been reported. We validated this sequence-based CNV call set with array comparative genomic hybridization (aCGH), quantitative PCR (qPCR), and fluorescent in situ hybridization (FISH), achieving a validation rate of 82% and a false positive rate of 8%. We further estimated absolute copy numbers for genomic segments and annotated genes in each individual. Surveys of the top 25 most variable genes revealed that the Nelore individual had the lowest copy numbers in 13 cases (similar to 52%, chi(2) test; P-value <0.05). In contrast, genes related to pathogen- and parasite-resistance, such as CATHL4 and ULBP17, were highly duplicated in the Nelore individual relative to the taurine cattle, while genes involved in lipid transport and metabolism, including APOL3 and FABP2, were highly duplicated in the beef breeds. These CNV regions also harbor genes like BPIFA2A (BSP30A) and WC1, suggesting that some CNVs may be associated with breed-specific differences in adaptation, health, and production traits. By providing the first individualized cattle CNV and segmental duplication maps and genome-wide gene copy number estimates, we enable future CNV studies into highly duplicated regions in the cattle genome.

Effects of CSN3 and LGB gene polymorphisms on production traits in beef cattle

The objective of the present study was to estimate the allele and genotype frequencies of the CSN3/Hinfl and LGB/HaeIII gene polymorphisms in beef cattle belonging to different genetic groups, and to determine the effects of these polymorphisms on growth and carcass traits in these animals, which are submitted to an intensive production model. Genotyping was performed on 79 Nelore, 30 Canchim (5/8 Charolais + 3/8 Zebu) and 275 crossbred cattle originating from the crosses of Simmental (n = 30) and Angus (n = 245) sires with Nelore females. Body weight, weight gain, dressing percentage, longissimus dorsi area and backfat thickness were fitted using the GLM procedure, and least square means of the genotypes were compared by the F test. The results showed that the CSN3/Hinfl and LGB/HaeIII polymorphisms did not have any effect on growth or carcass traits (p > 0.05). Copyright by the Brazilian Society of genetics.

Influência da raça do touro (Bos indicus x Bos taurus) na tolerância ao estresse térmico calórico de embriões bovinos produzidos in vitro

To better understand the differences related to HS resistance between Bos indicus and Bos taurus, we aim to verify if the HS tolerance is due mostly to the genetic contribution from the oocyte, spermatozoa or both. Oocytes from Nelore and crossbreed Holstein cows (cHST) were collected, matured and fertilized with semen from Nelore (N), Angus (An), Brahman (Bra) and Gir (Gir) bulls. Nine six hours post insemination (hpi), ≥ 16 cells embryos were separated in two groups: control and HS. In control group, embryos were cultured at 39°C, whereas in the HS group, embryos were subjected to 41°C for 12 h, and then returned to 39°C. There was no effect of HS on blastocyst and hatched blastocyst rates in all breeds analyzed. The percentage of oocytes that cleaved and reached morula stage was significantly lower (p < 0.05) in cHST x Gir as compared to the other breeds. Additionally, blastocyst rates was higher in cHST x N than in cHST x An and cHST x Gir (p < 0.05). It was concluded that the oocyte is more important than the spermatozoa for the development of thermotolerance, since the breed of the bull did not influence embryo development after HS.

Desempenho de novilhas de corte alimentadas com cana hidrolisada

The objective of this study was to evaluate the performance, consumption and feed conversion of Angus x Nellore heifers fed hydrolyzed sugarcane. Twenty-four (1/2 Angus x Nellore crossbred) heifers were used with average body weight of 242 kg ± 23 kg, confined in individual pens with total area of 15 m2. The study consisted of six treatments distributed as follows: T1-in natura sugarcane: sugarcane was given to animals after being chopped; T2-hydrolyzed sugarcane with 0.5 % lime and 24 hours of air exposure; T3-hydrolyzed sugarcane with 0.5 % lime and 48 hours of air exposure; T4-hydrolyzed sugarcane with 1.0 % lime and 24 hours of air exposure; T5-hydrolyzed sugarcane with 1.0 % lime and 48 hours of air exposure; T6-hydrolyzed sugarcane with 1.0 % lime and 72 hours of air exposure. We used a completely randomized design with four replicates per treatment, and averages were compared by Tukey test at 5 % significant level of probability. No statistical difference was found for any of the treatments (P>0.05). The processing of sugarcane with lime did not increase the intake and performance of animals evaluated in this study.

Fontes energéticas associadas ao farelo de girassol ou à ureia em dietas para novilhos

The objective of this study was to evaluate the performance and carcass traits of steers fed corn or citrus pulp associated with sunflower meal or urea. Diets were composed of two energy sources (corn grain and citrus pulp) associated with two protein sources (soybean meal and urea), resulting in four treatments in forage:concentrate ratio of 40:60. It were used 24 steers, 1/2 Angus × 1/2 Nellore (18 months old and 329 kg BW) distributed in a completely randomized design which were finished in feedlot for 80 days. It were evaluated the intake, average daily gain and carcass traits of the animals. Intake of dry matter (DMI), crude protein (CPI) and neutral detergent fiber (NDFI) were affected (p<0.05) by diets. The diet with citrus pulp and urea (PU) showed the lowest (p<0.05) DMI (8.30 kg), CPI (1.03 kg) and NDFI (3.31 kg). The average daily weight gain (ADG) followed the behavior of DMI, NDFI and CPI and the lowest value (p<0.05) was observed for animals fed diet PU. Regarding carcass traits, diets containing corn associated with urea (MU) or sunflower meal (MFG) and citrus pulp associated with sunflower meal (PFG), provided the highest (p<0.05) carcass cold weights (238.37, 247.26 and 237.14 kg, respectively). However, the lowest cold carcass dressing percentage (p<0.05) was obtained in diet MU (50.57%). The association of citrus pulp with urea should not be performed when citrus pulp partially or totally replace corn as energy source in diets, because possibly this association promote an energy deficit resulting in lower performance and worse carcass traits of animals finished in feedlot.

Effects of heat stress on development, quality and survival of Bos indicus and Bos taurus embryos produced in vitro

Heat stress is an important cause of poor development and low survival rates in bovine embryos. Experiments were conducted to test the hypothesis that Bos indicus embryos are more resistant to heat stress than are Bos taurus embryos. In experiment 1, Nelore and Jersey embryos from oocyte pick-up-derived oocytes were submitted to heat stress (96 hours post-insemination, 41 °C, 6 hours), developmental ratios were assessed at Day 7 (Day 0 = day of fertilization), and blastocysts were frozen for RNA extraction. Experiment 2 evaluated expression of COX2, CDX2, HSF1, and PLAC8 in previously frozen blastocysts. In experiment 3, Nellore and Angus embryos from oocyte pick-up-derived oocytes were submitted to heat stress (96 hours post-insemination, 41 °C, 12 hours) and transferred to recipients on Day 7. In experiment 4, embryos developed as in experiment 3 were fixed for Terminal deoxynucleotidyl transferase dUTP nick end labeling labeling and total cell counting. In experiment 1, heat stress decreased the percentage of Jersey oocytes that became blastocysts, but had no effect on Nellore embryos (34.6%, 25.0%, 39.5%, and 33.0% for Jersey control, Jersey heat-stressed, Nellore control, and Nellore heat-stressed oocytes, respectively; P < 0.05). In experiment 2, heat stress decreased (P < 0.05) expression of CDX2 and PLAC8, with higher expression of these genes in Nellore embryos than in Jersey embryos. Heat stress also decreased (P < 0.05) expression of COX2 in Jersey embryos, but had no effect on Nellore embryos. Expression of HSF1 was decreased (P < 0.05) by heat stress in both breeds, with a greater effect in Nellore embryos. In experiment 3, heat stress tended (P = 0.1) to decrease the percentage of pregnancies among cows (Day 30 to 35) that received Angus embryos. In experiment 4, heat stress increased (P < 0.05) the percentage of apoptotic blastomeres, but had no breed-specific effects. In addition, Nellore embryos had fewer (P < 0.05) Terminal deoxynucleotidyl transferase dUTP nick end labeling- positive blastomeres than did Angus embryos. We concluded that the detrimental effects of heat stress were dependent upon embryo breed and were more evident in Bos taurus embryos than in Bos indicus embryos. © 2013 Elsevier Inc.

Detecting Loci under Recent Positive Selection in Dairy and Beef Cattle by Combining Different Genome-Wide Scan Methods

As the methodologies available for the detection of positive selection from genomic data vary in terms of assumptions and execution, weak correlations are expected among them. However, if there is any given signal that is consistently supported across different methodologies, it is strong evidence that the locus has been under past selection. In this paper, a straightforward frequentist approach based on the Stouffer Method to combine P-values across different tests for evidence of recent positive selection in common variations, as well as strategies for extracting biological information from the detected signals, were described and applied to high density single nucleotide polymorphism (SNP) data generated from dairy and beef cattle (taurine and indicine). The ancestral Bovinae allele state of over 440,000 SNP is also reported. Using this combination of methods, highly significant (P<3.17×10-7) population-specific sweeps pointing out to candidate genes and pathways that may be involved in beef and dairy production were identified. The most significant signal was found in the Cornichon homolog 3 gene (CNIH3) in Brown Swiss (P = 3.82×10-12), and may be involved in the regulation of pre-ovulatory luteinizing hormone surge. Other putative pathways under selection are the glucolysis/gluconeogenesis, transcription machinery and chemokine/cytokine activity in Angus; calpain-calpastatin system and ribosome biogenesis in Brown Swiss; and gangliosides deposition in milk fat globules in Gyr. The composite method, combined with the strategies applied to retrieve functional information, may be a useful tool for surveying genome-wide selective sweeps and providing insights in to the source of selection.

Effects of bovine somatotropin administration on growth, physiological, and reproductive responses of replacement beef heifers

This experiment compared growth, body composition, plasma IGF-I and leptin, and reproductive development of beef heifers receiving or not recombinant bovine ST (BST) beginning after weaning until the first breeding season. Fifty Angus × Hereford heifers (initial BW = 219 ± 2 kg; initial age = 208 ± 2 d), weaned at approximately 6 mo of age, were assigned to the experiment (d 0 to 210). On d 0, heifers were ranked by initial BW and age and assigned to 1) treatment with BST or 2) saline control. Heifers assigned to the BST treatment received subcutaneous (s.c.) injections containing 250 mg of sometribove zinc whereas control heifers received a 5-mL s.c. injection of 0.9% saline every 14 d. Treatments were initiated on d 14 and last administered on d 196. Heifers were maintained on separate pastures harvested for hay the previous summer according to treatment and received grass and alfalfa hay at a rate to provide a daily amount of 7.0 and 1.0 kg of DM per heifer, respectively. Heifer shrunk BW was collected on d 1 and 211 for heifer ADG calculation. Blood samples were collected weekly from d 0 to 210 for determination of plasma progesterone to estimate puberty attainment as well as plasma concentrations of IGF-I and leptin in selected samples. On d 0, 63, 133, and 189, heifers were evaluated for intramuscular marbling, LM depth, and backfat thickness via real-time ultrasonography. No treatment effects were detected (P = 0.27) for heifer ADG (0.49 vs. 0.51 kg/d for control and BST heifers, respectively; SEM = 0.02). Mean backfat thickness was lesser (P < 0.01) in BST heifers compared with control cohorts (3.56 vs. 3.92 mm, respectively; SEM = 0.08). Heifers receiving BST had greater plasma IGF-I concentrations compared with control cohorts 7 d after treatment administration (treatment × day interaction; P < 0.01). Mean plasma leptin concentrations were lesser (P = 0.05) in BST heifers compared with control cohorts (1.82 vs. 2.03 ng/mL, respectively; SEM = 0.07). Onset of puberty was hastened in BST heifers compared with control cohorts (treatment x day interaction; P = 0.04). In summary, a greater proportion of BST heifers reached puberty during the experiment compared with control cohorts, despite lesser plasma leptin concentrations, backfat thickness, and similar ADG. Hence, circulating IGF-I was positively associated with hastened puberty attainment independently of growth rate, circulating leptin concentrations, and body fat content of replacement beef heifers. © 2013 American Society of Animal Science. All rights reserved.