Predicting beef carcass retail products of Mediterranean buffaloes by real-time ultrasound measures

Twenty eight Mediterranean buffaloes bulls were scanned with real-time ultrasound (RTU), slaughtered, and fabricated into retail cuts to determine the potential for ultrasound measures to predict carcass retail yield. Ultrasound measures of fat thickness, ribeye area and rump fat thickness were recorded three to five days prior to slaughter. Carcass measurements were taken, and one side of each carcass was fabricated into retail cuts. Stepwise regression analysis was used to compare possible models for prediction of either kilograms or percent retail product from carcass mesaurements and ultrasound measures. Results indicate that possible prediction models for percent or kilograms of retail products using RTU measures were similar in their predictive power and accuracy when compared to models derived from carcass measurements. Both fat thickness and ribeye area were over-predicted when measured ultrasonically compared to measurements taken on the carcass in the cooler. The mean absolute differences for both traits are larger than the mean differences, indicating that some images were interpreted to be larger and some smaller than actual carcass measurements. Ultrasound measurements of REA and FT had positive correlations with carcass measures of the same traits (r=.96 for REA and r=.99 for FT). Standard errors of prediction currently are being used as the standard to certify ultrasound technicians for accuracy. Regression equations using live weight (LW), rib eye area (REAU) and subcutaneous fat thickness (FTU) between 12(th) and 13 (th) ribs and also over the biceps femoris muscle (FTP8) by ultrasound explained 95% of the variation in the hot carcass weight when measure immediately before slaughter.

Desempenho em pastagens e características de carcaça da 16a progênie dos rebanhos Nelore, Guzerá e Caracu de Sertãozinho (sp)

Forty one young bulls of herds selected for 378 day's weight (W378), born in 1996, were finished on pastures of Panicum Maximum (Jacq.), Panicum Maximum (Jaq) cv. Tanzania 1 and Brachiaria brizantha (Hoschst) Stapf cv. Marandu at the Sertaozinho Experimental Station, São Paulo State, Brazil. The samples, representing the W378 mean for each herd, were composed by 11 Nellore Selection (NeS) and by 10 of each one of the groups Nelore Control (NeC), Guzera Selection (GuS) and Caracu (Ca). The slaughter was carried out when the animals were 824 days older, with a body condition score averaging 7.6, in a 1-9 scale. The minimum and maximum adjusted means for the main traits, including all groups, were: average weight daily gain, 406 (NeC) and 501 g (NeS); slaughter weight (SW), 446.8 (NeC) and 544.3 kg (NeS); carcass weight (CW), 249.8 (NeC) and 309.7 kg (NeS); dressing percentage (DP), 54.0 (GuS) and 56.3% (NeC and NeS). In the 9(th) - 11(th) rib section: muscle, 59.6 (NeC) and 65.2% (Ca); fat, 15.6 (Ca) and 21.4% (NeC); bone, 18.9 (NeC) and 20.2% (GuS); fat thickness (FT), 2.0 (Ca) and 4.2 mm (NeC); loin eye area, 65.6 (NeC) and 71.1 cm(2) (NeS and Ca); Warner-Bratzler shear force (SF), 4.5 (Ca) and 6.6 kg (GuS) and total cooking losses (TCL), 22.5 (NeC) and 24.9% (GuS). The selection for weight promoted higher SW and CW in the NeS group, without changing the DP, the physical composition of the rib, SF and TCL in the meat. However, there was lower FT compared to NeC. The GuS animals had intermediates SW and CW, compared to NeS and Ca and lower DP. The Ca animals presented higher muscle percentage, in the rib section, and also higher meat tenderness compared to the meat of the Zebu animals.

Effect of grazing system on fetal development in Nellore cattle

Intensive grazing systems for beef females, based on abundant availability of high quality forages and supplementary concentrates, may affect fetal development. The objective of this study was to determine the effect of grazing system on length of gestation, fetal development, and characteristics of the calf at birth. Twenty-four pregnant (bred to Nellore bulls) Nellore females were allocated into two groups. The control group (G1) grazed Brachiaria decumbens (signal grass) in a traditional (extensive) grazing system and the second group (G2) were managed on Panicum maximumcv. Tanzania 1 (Tanzania grass) in an intensive grazing system. Fetal development was evaluated by ultrasonography on days 31, 45, 59, 94, 122, 220, and 255 of gestation. The diameter of the amniotic and allantoic cavities, crown-rump length, circumference, and diameter of the head and ocular orbit were determined. At birth, calves were weighed and height, length, thoracic circumference, and ocular orbit and bi-parietal diameters were measured. There were no differences (P > 0.05) in fetal development. The G1 cows had a longer gestation period (4.5 days; P < 0.05) and their calves had greater (P < 0.05) weight, height, length, and thoracic circumference at birth. In conclusion, Nellore females raised under intensive pasture management conditions, had significantly shorter gestation and smaller calves at birth than those raised under extensive pasture management conditions. Therefore, adoption of new management practices (e.g. intensive pasture management), should take into consideration animal behavior and productivity. (C) 2003 Elsevier B.V. All rights reserved.

Fertility-associated proteins in Nelore bull sperm membranes

The present study was undertaken to evaluate the protein composition of the sperm membranes (SM) of Nelore bulls, assessing protein markers associated with bull fertility, and whether these markers can be used for predicting bull fertility. Samples were obtained of 20 Nelore bulls, with fertility ranked and divided into three groups (greater, normal and least). To rank the bull's fertility weighted classification was used (according to the number of pregnant cows, number of AI cows and number of herds, considering three different breeding seasons), using the PROC GENMOD as a statistical model, with 99% significance. A total of 7897 Nelore cows, randomly distributed among 28 different farms, were considered in the statistical analyses. The bulls were divided into three fertility groups (pregnancy rates): greater (%F > 80), normal (79 <%F > 71) and least (< 68%F) with 3, 13 and 4 bulls, respectively. Two-dimensional gel electrophoresis (2DE) of sperm membranes indicated in 27 spots (SM40, SM53, SM69, SM93, SM102, SM111, SM137, SM138, SM189, SM196, SM201, SM202, SM204, SM225, SM236, SM237, SM239, SM241, SM246, SM247, SM275, SM283, SM342, SM346, SM355, SM372, SM391) was prevalent in the higher fertility group, and just one spot (SM244) was prevalent in the lower fertility group. Spots SM244 and SM239 had their identification defined by PMF/MALDI-MS, as BSP-A3 and aSFP, respectively. Both these proteins showed a great potential for predicting bull's fertility. The amount of aSFP was 8.5 times greater in the sperm membrane protein profile of the higher fertility groups of Nelore bulls. Besides that, the BSP-A3 was 2.5 times greater in the lower fertility group. For the other spots potentially associated with fertility not yet identified, additional tests will be necessary, but it is clear that the 2D electrophoresis of the sperm membrane can be used for a new approach to predict Nelore bull fertility. (c) 2005 Elsevier B.V. All rights reserved.

Puberty in South American Bos indicus (Zebu) cattle

Puberty in Zebu heifers follows a pattern characterized by a decrease in the steroid feedback mechanism and an increase in LH concentration, which result in the first ovulation followed by a short estrous cycle and the onset of normal cycles thereafter. These events are similar to those observed in Bos taurus cattle but occur at a later age. The late onset of puberty is both genetic and environmental in origin and is reflected by the age at first calving that can be at 40 months of age or older in these animals. Age at puberty in Zebu heifers has been shown to have a high heritability. Consequently, selecting precocious heifers may be an effective means of reducing age at puberty in these animals and this approach is being adopted in commercial practice. Genetic selection is not the sole solution to the problem because environmental improvements are necessary, particularly in terms of improved nutrition. South American Zebu cattle are usually subject to sub-optimum nutritional and management conditions and, hence, exhibit late onset of puberty. Hybrids of Zebu and Bos taurus cattle exhibit heterosis in respect of the age of puberty with earlier onset than expected in crossbred animals. Recently, purebred South American Zebu cattle have been shown to have Bos taurus genes, indicating that there have been previous attempts to improve their productivity using this approach. It was concluded that the age at first calving in South American Zebu cattle can be reduced by exposing well-fed, yearling heifers to bulls and selecting, over several generations, those animals that become pregnant at an early age. (C) 2004 Published by Elsevier B.V.

Influence of sire breed (Bos indicus versus Bos taurus) and interval from slaughter to oocyte aspiration on heat stress tolerance of in vitro-produced bovine embryos

Based on in vitro experiments, Bos indicus embryos were more resistant to heat stress (HS) than Bos taurus embryos. To increase knowledge regarding differences between Bos indicus and Bos taurus in resistance to HS, the primary objective of this study was to determine if tolerance to HS is due to the breed, origin of the oocyte, sperm, or both. Additionally, the influence of the interval between ovary acquisition (in the abattoir) and oocyte aspiration in the laboratory, on early embryo development was ascertained. Oocytes were collected from Nelore and Holstein cows in an abattoir; 4.0 or 6.5 h later, oocytes were aspired in the laboratory, and then matured and fertilized using semen from Nelore (N), Gir (GIR), or Holstein (H) bulls. Ninety-six h post insemination (hpi), embryos with >= 16 cells were divided in two groups: control and HS. In the control group, embryos were cultured at 39 degrees C, whereas in the HS group, embryos were subjected to 41 degrees C for 12 h, and then returned to 39 degrees C. Rates of cleavage, and formation of morula and blastocysts were higher (P < 0.05) for oocytes aspirated at 4.0 versus 6.5 h after ovaries were acquired. Heat stress decreased rates of blastocyst formation for all breeds (N X N; H x H; and H X GIR) and in both time intervals (4.0 and 6.5 h). However, N X N had higher cleavage rate (P < 0.05) in both time intervals when compared with H X H and H X GIR. In addition, Nelore oocytes fertilized with Nelore semen (N X N) had higher blastocyst yields (P < 0.05) in the control and HS group, when compared with the other two breeds (H X H and H X GIR). We concluded that the breed of origin of the oocyte was more important than that of the sperm for development of thermotolerance, because bull breed did not influence embryo development after HS, and in vitro early embryonic development was impaired by increasing (from 4 to 6.5 h) the interval between ovary acquisition and oocyte aspiration. (C) 2011 Elsevier B.V. All rights reserved.

Additive genetic relationships between scrotal circumference, heifer pregnancy, and stayability in Nellore cattle

Scrotal circumference data from 47,605 Nellore young bulls, measured at around 18 mo of age (SC18), were analyzed simultaneously with 27,924 heifer pregnancy (HP) and 80,831 stayability (STAY) records to estimate their additive genetic relationships. Additionally, the possibility that economically relevant traits measured directly in females could replace SC18 as a selection criterion was verified. Heifer pregnancy was defined as the observation that a heifer conceived and remained pregnant, which was assessed by rectal palpation at 60 d. Females were exposed to sires for the first time at about 14 mo of age (between 11 and 16 mo). Stayability was defined as whether or not a cow calved every year up to 5 yr of age, when the opportunity to breed was provided. A Bayesian linear-threshold-threshold analysis via Gibbs sampler was used to estimate the variance and covariance components of the multitrait model. Heritability estimates were 0.42 +/- 0.01, 0.53 +/- 0.03, and 0.10 +/- 0.01, for SC18, HP, and STAY, respectively. The genetic correlation estimates were 0.29 +/- 0.05, 0.19 +/- 0.05, and 0.64 +/- 0.07 between SC18 and HP, SC18 and STAY, and HP and STAY, respectively. The residual correlation estimate between HP and STAY was -0.08 +/- 0.03. The heritability values indicate the existence of considerable genetic variance for SC18 and HP traits. However, genetic correlations between SC18 and the female reproductive traits analyzed in the present study can only be considered moderate. The small residual correlation between HP and STAY suggests that environmental effects common to both traits are not major. The large heritability estimate for HP and the high genetic correlation between HP and STAY obtained in the present study confirm that EPD for HP can be used to select bulls for the production of precocious, fertile, and long-lived daughters. Moreover, SC18 could be incorporated in multitrait analysis to improve the prediction accuracy for HP genetic merit of young bulls.

Modelos lineares generalizados mistos na avaliação genética da prenhez precoce na raça Nelore

This study aimed to use the generalized linear models with probit and logit link function to evaluate early pregnancy, and to observe the effects on genetic variability and on sire selection when different ages are adopted in the definition of this trait. Early pregnancy was studied at 15 (EP15), and 21 (EP21) months. The analysis was done in R software. Pearson correlations (PC), between genetic predicted values and percentage of bulls in common considering only 10% of bulls with higher genetic values (TOP 10), between classification by logit and probit models and in each model among EP15 and EP21, were calculated. The heritability for EP15 and EP21 were close between models, except for EP15 using probit link function. PC and TOP10 among models were high. The Akaike and Bayesian criteria reported was similar between models. TOP10, considering the same model, among EP15-EP21 were moderated between EP15-EP21.

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)

Bull semen varibles after experimental exposure with Bovine Herpesvirus type 5

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

Additive genetic relationship of longevity with fertility and production traits in Nellore cattle based on bivariate models

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

Estimativa da mudança genética na produção de leite e gordura em bovinos da raça Holandesa

The objective of this study was to estimate the genetic trends of the milk and fat yield in three herds maintained in São Paulo State, Brazil. The estimation of genetic, environmental and phenotypic trends were based on 716 first lactations. The cows were sired by 134 bulls. The statistical models included the fixed effects of herds, kind of gestation, season and year of the calving, age of the cow at calving, besides the random effect of the bulls. The statistical analyses, by the last squares method showed effects for bulls, herds and age of the cows on milk and fat yield. The genetic, environmental and phenotypic trends estimated were -10.20; 6.74 and -3.46 kg for milk yield and -1.90; 2.20 and 0.12 kg for fat yield.

Efeito da somatotropina bovina recombinante no desempenho e nas características químicas da carne de bovinos

The objective of this study was to evaluate the effects of the use of recombinant bovine somatotropin (rbST) in weight gain, feeding efficiency and chemical characteristics of meat of young bulls. Fifty nine young bulls were used: 30 crossbred Simmental x Nelore and 29 Nelore aging between seven to eight months, weighing 236 and 116 kg, respectively. A randomized experiment in a 2 × 2 factorial arrangement was used. There were two levels of rbST (0 and 250 mg/animal/14 days) and two breed groups subdivided in two experimental phases. Diet was based on corn silage and concentrate aiming at a weight gain of 0.8 a day for Phase I (70 days) and 1.3 kg for Phase II (98 days). Animals were slaughtered at 13 months of age and the measurements of carcass dressing and meat quality were taken. Results showed that cross-breeding animals overcame (p<.01) the Nelore breed in weight gain and final weight at slaughtering. Use of rbST has not influenced weight gain, final weight, carcass weight and chemical characteristics of meat (p>.05). The use of rbST improved feeding efficiency 11.91 % for cross-bred and 24.32% for Nelore in Phase II.

Efeitos da restrição alimentar no desempenho de bovinos jovens confinados

The objective of the study was to evaluate compensatory weight gain in the performance of young bulls submitted to feed restriction, in the initial phase of confinement and to study the economic viability of the utilization of three protein sources. Sixty six crossbred bulls Simental-Nelore, eight months old and averaging 220 kg of weight were submitted to three feeding programs in the growth phase that lasted 84 days. The feeding programs were ad libitum, restriction + raw soybean grains and restriction + toasted soybean grains, with a restriction level of 25% on average. In the finishing phase, with a 61 day duration, animals fed with each of the three diets mentioned above received two types of supplementary diets: raw soybean grains and poultry litter. There were no differences between final weights of animals in finishing phase, but the bulls submitted to the restriction had more weight gain per day and better food conversion than ad libitum animals, for both raw soybean grains and poultry litter. The conclusion was that the feeding restriction and consequent compensatory weight gain, presented advantages for feeding efficiency, by decreasing maintenance requirements, although final cost had been equivalent to ad libitum animals.

Estudo dos efeitos da restrição alimentar nas características das fibras musculares de bovinos jovens confinados

The influence of restricting feed intake of young bulls in feedlots was evaluated in terms of structure of muscular fibers and respective areas, sampled by biopsy on the semitendinoso muscle. Sixty six crossbred Simental-Nelore bulls, 8 months old, averaging 220±34.03 kg were submited for 84 days in phase 1 (growing period), to three treatments: ad libitum (AL), restriction + whole soybean (RWS) and restriction + toasted whole soybean (RTS). The level of restriction of feed intake was 23%. Phase 2 was performed by splitting the animals in each treatment in phase 1 in two groups, feeding one with a diet containing soybeans and the other with poultry litter. The results showed that the animals AL presented more white fibers (FG), compared to the RWS and RST and a larger area of these fibers. A greater frequency of red fibers was observed in treatments RWS and RST. The conclusion was that the restriction of feed intake and consequent compensatory growth contributed for modulation of the muscular fibers increasing the frequency of the fast oxidative glycolitic (FOG) in 10.88% and decreasing of the slow oxidative (SO) and FG in 4.81 and 6.90%, respectively, with possible alteration on meat quality.