Kg Of Empty Body Weight Research Articles

177 Determining the Body Weight to Body Fat Conversion Factor for Angus, Charolais, and Brahman Growing Steers

Abstract The profitability of beef feedlot operations depends on accurately predicting the energy and nutrient requirements of the animal to optimize animal growth and carcass quality to meet market specifications. The composition of the gain (i.e., fat and protein) dictates the growth of the animal, and it is highly correlated with the body composition of the mature animal, assuming that the composition of body gain is constant for animals at the same maturity degree. Once the mature weight for a given body composition (i.e., fat) is known, the maturity degree can be estimated, and the equivalent body weight (EqBW) can be used to calculate energy requirements for growth. Several standard feeding systems and nutrition models use the adjusted final body weight (AFBW) at a known fat composition to estimate EqBW. The AFBW is the body weight (BW) at, usually, 28% empty body fat (EBF). Thus, AFBW can be estimated if a given empty BW (EBW) and composition are known, and an EBW-to-EBF factor is used to calculate AFBW from the current BW. Several nutrition models, including the Cattle Value Discovery System, have adopted the 14.26 kg of EBW for each % of EBF. Therefore, this study aimed to determine the amount of body mass deposited per change in body fat content of different breeds commonly used in Australia. We randomly allocated 30 Angus, 30 Brahman, and 29 Charolais into six slaughter groups (6 animals per breed per slaughter group) fed for up to 200 days. Internal organs and carcasses were dissected into physically separable fat, lean, and bones. When we regressed EBW on EBF, the overall regression yielded a slope of 11.2 ± 0.69 kg/%EBF [n = 89, r2 = 0.75, and root of the mean square error (RMSE) = 55.7 kg], likely not different from the 14.26 kg/% EBF. However, slopes were different among breeds (P < 0.001), i.e., there was an interaction between breeds and EBF when the breed was added to the ordinary least-square mean regression as a classificatory variable. The slopes were 16.5 ± 0.84 kg/% for Charolais (n = 29, r2 = 0.933, RMSE = 33.2 kg), 13.2 ± 0.73 kg /% for Angus (n = 30, r2 = 0.921, RMSE = 34.4 kg), and 10.1 ± 1.06 kg/% for Brahman (n = 30, r2 = 0.765, RMSE = 38.3 kg). When we regressed the amount of EBF on EBW, we obtained 0.40, 0.58, and 0.52 kg EBF/kg EBW for Charolais, Angus and Brahman, respectively. This confirms that Charolais deposited less EBF per unit of gain compared with Angus and Brahman. Given the similarity between the 14.26 kg/% to the overall value of 11.2 kg/%, we recommend using the 14.26 EBW-to-EBF factor to estimate AFBW when the genetic group is unknown.

PSVII-24 Weight at maturity of water buffaloes determined by body chemical composition

Abstract This study determined the weight at maturity (WM) of water buffaloes of three genetic groups (GG:Jafarabadi, Mediterranean, and Murrah) slaughtered at different weights (420, 480, and 540 kg). One-hundred-fifty-three non-castrated male (means of initial body weight and age of 314 ±117 kg and 390 ±32 days, respectively) from two similar experiments were used. The animals were slaughtered and the non-carcass components of each animal were weighed to obtain the empty body weight (EBW). The left half-carcasses were dissected into muscle, fat, and bone. Each tissue of each animal was ground separately and subsequently aliquoted for further analyses. The determination of moisture, crude protein (CP), ether extract (EE), and ash was performed by the classical method. Nonlinear regressions were used to predict the body composition of water, CP and ash. An exponential model was used to adjust the data for the content of the EE. Random coefficient models were used to identify fixed and random effects using the NLMIXED procedure in SAS. The genetic group was tested as fixed effect and year as a random effect. Body CP was determined based on CP fat-free dry matter (CPFFDM). The equations predicted the body composition of CP, EE, water and ash, and the results were expressed as a percentage of the EBW. WM was estimated when the non-significant increase in CPFFDM was no longer observed. There was effect of GG for WM model (P = 0.037), thus the WM was determined for each GG. The models suggest that Jafarabadi reach maturity at ~505.93kg of EBW [WMCPFFDM=79.279×(1–1.17×e-0.010×EBW)]; Mediterranean reach maturity at ~494.40kg of EBW [WMCPFFDM=79.186×(1–1.18×e-0.011×EBW)]; Murrah reach maturity at ~423.79kg of EBW [WMCPFFDM=78.793×(1–11.99×e-0.018×EBW)]. In conclusion, the WM of water buffaloes is dependent on the GG reaching 505.93, 494.90, 423.79 kg of EBW for the Jafarabadi, Mediterranean, and Murrah genetic groups, respectively.

PSVII-4 Effect of the residual gain and genetic group on body chemical composition of water buffaloes

Abstract This study evaluated the effect of residual gain (RG) on body chemical composition of water buffaloes of three genetic groups (GG:Jafarabadi, Mediterranean, and Murrah) and verify the presence of chemical variables related to this efficiency measure. One-hundred-forty-eight non-castrated male (338.29 ±64.16 kg initial body weight; 370 ±28 days of initial age) from two similar experiments were used. The animals remained in feedlot and were slaughtered after 240 days (adaptation+trial periods). The RG was calculated considering 84 days after adaptation period. After the slaughter the empty body weight (EBW) of each animal was obtained and the left half-carcasses were dissected into muscle, fat, and bone, after 24h of cooling. The chemical composition [moisture, crude protein (CP), ether extract (EE), and ash] of each ground tissue was analyzed by the classical method. The body CP was also determined based on CP fat-free dry matter (CPFFDM). Data were analyzed using MIXED procedure in SAS. The class of RG, genetic group, and the resulting interaction were tested as fixed effect and year as a random effect. The variable results are reported as kg of EBW. There was no interaction effect (P ≥ 0.11) for the variables studied. Effect of class of RG was detected for the variables EBW (P = 0.021), water (P = 0.016), and EE (P = 0.035), while tendency was observed for CP (P = 0.074), for which animals classified as more efficient for residual gain demonstrated high values (Table 1). Furthermore, there was effect of GG for EBW (P = 0.002), water (P < 0.001), and CP (P = 0.014) variables. Tendency of GG effect was observed for ash (P = 0.085) and EE (P = 0.057). Jafarabadi showed high values for all the variables cited. In conclusion, there are difference in the body chemical composition of water buffaloes according to the animal efficiency evaluated by residual gain, as well as according to genetic groups. Supported by FAPESP (#2014/05473-7).

Characteristics of the non-carcass components of steers fed different sources of dietary carbohydrates

We evaluated the characteristics of the non-carcass components of 24 steers (Charolais × Nelore) fed different carbohydrate sources (ground corn, soybean hulls, or wheat bran) in the diet. The animals were 353.2 kg and 22 months of age at early termination, and had been fed forage consisting of sorghum silage at a forage:concentrate ratio of 40.2:59.8. The carbohydrate sources had no effect on the weights of the carcass, vital organs, and blood. The absolute weights of the intestines and rumen fat were higher (P < 0.05) in animals fed corn than in those fed soybean hulls or wheat bran (10.87 vs. 8.89 and 8.87 kg and 5.26 vs. 4.12 and 3.64 kg, respectively). The same pattern was observed when these organs weights were adjusted for empty body weight. The weight of the omasum was highest (P < 0.05) in the wheat bran-fed animals (6.02 vs. 4.70 and 5.49 kg in the corn- and soybean hull-fed animals, respectively). Animals fed soybean hulls had a higher absolute weight of kidney fat (1.6 kg) than steers receiving wheat bran (1.06 kg) or corn (0.79 kg). Wheat bran gave the highest leg weight compared with corn and soybean hulls (2.46 vs. 2.22 and 2.23 kg per 100 kg of empty body weight, respectively).

Componentes não integrantes da carcaça de novilhos terminados em confinamento recebendo ureia protegida ou agrícola em substituição ao farelo de soja

The effect of termination of steers in a feedlot using the total substitution of soybean meal by slow-release or agriculture urea on the non-carcass components was evaluated. Twenty-seven purebred and Charolais × Nellore castrated crossbred steers (mean age 20 months, mean initial weight 293 kg) were allocated to received concentrates containing slow degradation urea, soybean meal, or agricultural urea. The experimental design was in randomized blocks (breed predominance), with three treatments and nine replicates, with the animal being the experimental unit. Diets did not lead to significant differences in empty body weight (EBW). The similarity between treatments was also verified in relation to EBW/slaughter weight, with mean values of 0.87 for treatments containing urea and 0.88 for soybean meal treatment. The gastrointestinal contents, both in absolute weight and in relation to EBW, were similar between the rations evaluated, with mean values of 54.33 kg and 13.52%, respectively. Steers fed with slow-release urea had a 32.8% higher weight of omasum relative to 100 kg of EBW (P < 0.05) compared to the animals fed with soybean meal.

Using growth and body composition to determine weight at maturity in Nellore cattle

The aim of the present study was to estimate the relationships among water, crude protein (CP), ether extract (EE) and ash in the empty bodyweight (EBW), and the soft tissue and bone and, moreover, to determine an objective method to define weight at maturity in Nellore cattle. A dataset containing carcass and body compositions of 249 animals from 11 experiments was developed. There were 63 bulls, 105 steers, and 81 heifers where all animals were purebred Nellore, aged between zero and 24 months. The contents of water, CP and ash in the EBW were predicted by non-linear regressions, whereas an exponential model was used to predict EE. In addition, the content of CP was predicted on a fat-free dry matter (FFDM) basis, and maturity was defined as the point when no significant accretion of CP in the FFDM was observed. The soft tissue water (STW) was regressed on logistic Gompertz functions, and segmented regression models, whereas the analysis of bone chemical composition in the EBW was conducted using an exponential model. The gender effect was not significant (P > 0.05) for EBW and EE; therefore, this effect was not included in the analysis of FFDM. The exponential model suggests that Nellore cattle reached maturity at ~445 kg and the segmented regression model suggested that maturity was reached at 429 kg. A significant relationship between the concentration of STW and soft tissue EE (STEE) was observed (STEE = 0.920 – 1.147 × STW; r2 = 0.96, mean square error = 1.01), but the soft tissue was not a good predictor of maturity, because it is dependent on the diet. Analysis of bone chemical composition showed that EE, water and ash become constant between 400 and 500 kg of EBW, and that CP in bones was constant at 19.1% of EBW. These data also suggested that bone composition could be a good predictor of maturity; however, with the high variability in our dataset, it was not possible to determine an EBW at which these components became constant with a reliable precision. We concluded that Nellore cattle reach maturity at ~437 kg of EBW and that CP in the FFDM and CP, water and ash in bones are good predictors of maturity, whereas soft tissue composition is not a useful predictor of maturity.

Energy requirements for maintenance and growth of male saanen goat kids.

The aim of study was to determine the energy requirements for maintenance and growth of forty-one Saanen, intact male kids with initial body weight (BW) of 5.12±0.19 kg. The baseline (BL) group consisted of eight kids averaging 5.46±0.18 kg BW. An intermediate group consisted of six kids, fed for ad libitum intake, that were slaughtered when they reached an average BW of 12.9±0.29 kg. The remaining kids (n = 27) were randomly allocated into nine slaughter groups (blocks) of three animals distributed among three amounts of dry matter intake (DMI; ad libitum and restricted to 70% or 40% of ad libitum intake). Animals in a group were slaughtered when the ad libitum-treatment kid in the group reached 20 kg BW. In a digestibility trial, 21 kids (same animals of the comparative slaughter) were housed in metabolic cages and used in a completely randomized design to evaluate the energetic value of the diet at different feed intake levels. The net energy for maintenance (NEm) was 417 kJ/kg0.75 of empty BW (EBW)/d, while the metabolizable energy for maintenance (MEm) was 657 kJ/kg0.75 of EBW/d. The efficiency of ME use for NE maintenance (km) was 0.64. Body fat content varied from 59.91 to 92.02 g/kg of EBW while body energy content varied from 6.37 to 7.76 MJ/kg of EBW, respectively, for 5 and 20 kg of EBW. The net energy for growth (NEg) ranged from 7.4 to 9.0 MJ/kg of empty weight gain by day at 5 and 20 kg BW, respectively. This study indicated that the energy requirements in goats were lower than previously published requirements for growing dairy goats.

Energy requirements for maintenance and growth of Canindé goat kids

Accurate values for energy requirements are necessary for the proper feeding management of goats. The aim of this study was to estimate the energy requirements for maintenance and growth of Canindé goat kids. We used 33 castrated goat kids with an average initial weight of 15.62±0.87kg. Five of them (baseline) were slaughtered at the beginning of the experiment to determine the initial body composition. The other goats (n=28) were assigned in a randomized block design into seven groups of four animals each. The diet consisted of 55% forage (Tifton) and 45% concentrate. The treatments consisted of four levels of intake: ad libitum and 80%, 60% and 40% of the ad libitum intake. Each group was slaughtered when the animal from the ad libitum level reached 26.55±0.65kg. We used the comparative slaughter method to assess body composition and calculate the nutritional requirements. Body composition varied from 177.43 to 166.98g of protein, from 127.92 to 193.46g of fat and from 2.15 to 2.69Mcal of energy per kg of empty body weight (EBW). The ratio of empty body weight/body weight was 0.81. The net energy requirements for maintenance were estimated at 52.64kcal/kg EBW0.75. The net requirements to gain ranged from 2.96 to 4.84Mcal/kg EBW gain for the castrated indigenous goat kids weighing between 15kg and 25kg. The energy requirements to maintenance of indigenous goat kids are lower, which might indicate different adaptive capabilities, but these goats require more energy to gain and to accumulate fat in their body.

Componentes não-integrantes da carcaça de bovinos de três grupos genéticos terminados em confinamento ou pastejo rotacionado com suplementação

Foram avaliados os componentes não-integrantes da carcaça de bovinos castrados (novilhos) Brahman, Brangus e Hereford terminados em confinamento ou pastejo com suplementação (capim-mombaça). Os animais foram abatidos com espessura de gordura subcutânea superior a 4mm. A dieta do confinamento foi formulada com 60% de volumoso e 40% de concentrado, com 13% PB e 62% NDT. O capim mombaça apresentou 7% de PB e 56%NDT e o suplemento apresentou 24% PB e 76% NDT. O delineamento experimental foi inteiramente casualizado, com arranjo fatorial 3x2 (três grupos genéticos e dois sistemas de terminação) e as médias foram comparadas pelo teste de Tukey ajustado. Foram observadas diferenças significativas para o peso de abate (PA) e peso do corpo vazio (PCV) favorável aos animais mantidos em pastejo com suplementação (444,03 vs 416,50kg para PA e 409,68 vs 375,24kg para PCV), entretanto não houve diferença significativa entre os sistemas de terminação para o rendimento de corpo vazio (RCV). O menor percentual de órgãos vitais foi apresentado pela raça Brahman independente do sistema de terminação utilizado (2,19%). A mesma tendência foi observada para o trato digestivo com um percentual de participação de 3,77% PCV do Brahman vs 4,87% e 4,48% PCV do Hereford e Brangus, respectivamente. Os novilhos Brahman apresentaram menores pesos de coração, pulmão e baço que os Hereford e Brangus. Os animais terminados em pastejo apresentaram maiores pesos de abomaso, pulmão e rins que os terminados em confinamento, 0,47 vs 0,35% PCV; 0,77 vs 0,71% PCV e 0,77 vs 0,71% PCV, respectivamente.

Performance, growth, and maturity of Nellore bulls

The objectives of this study were to evaluate the dry matter intake (DMI), digestibility, average daily gain (ADG), microbial efficiency, empty body weight (EBW) gain, and body composition of Nellore bulls. Additionally, Nellore bull maturity was estimated, and the prediction equation for DMI, suggested by the Brazilian nutrient requirements system (BR CORTE; Azevêdo et al. 2010), was evaluated. Thirty-three Nellore bulls, with a mean initial weight of 259 ± 25kg and age of 14 ± 1months, were used in this study. Five animals were slaughtered at the beginning of the experiment (control group), and the remaining 28 were divided into 4 groups, each slaughtered at 42-day intervals. Their diet was composed of corn silage and concentrate (55:45). The power model was used to estimate muscle tissue, bone tissue, crude protein (CP), mineral matter (MM), and water present in the empty body, while the exponential model was used to estimate adipose tissue and ether extract (EE) present in the empty body. When expressed in kilograms per day, differences were observed (P < 0.05) only for the intake of EE and neutral detergent fiber as a function of feedlot time periods. Although there was a difference in relation to nutrient intake, it did not affect (P > 0.05) digestibility, with the exception of EE digestibility. The equation suggested by BR CORTE correctly estimates the DMI of Nellore bulls. ADG was not affected (P > 0.05) by time spent in the feedlot. No differences were observed (P > 0.05) for microbial efficiency; a mean value of 142g microbial crude protein/kg total digestible nutrients was achieved. The muscle and bone tissues, CP, MM, and water present in the empty body increased as the animal grew, although at a lower rate. The adipose tissue and EE present in the empty body increased their deposition rate when the animal reached its mature weight. Maturity is defined as when an animal reaches 22% EE in the empty body, which corresponds to 456kg of EBW in Nellore bulls. Therefore, this study can conclude that the feedlot time period does not affect DMI, nutrient intake, ADG, or microbial efficiency. The equation proposed by BR CORTE (Azevêdo et al. 2010) correctly estimates the DMI of Nellore bulls, which reach maturity when an EBW of 456kg is attained.

Carcass characteristics of Criollo Cordobés kid goats under an extensive management system: Effects of gender and liveweight at slaughter

Thirty males and thirty females suckling Criollo Cordobes kid goats of approximately 60 to 90 days old were used in this study. Kids were slaughtered at <9.5 kg, >9.5<11 kg and >11 kg of empty body weight. The carcasses showed a medium conformation index. The meat and fat colour, and internal subcutaneous fatness were mainly scored as either pink, cream, slight and low-medium, respectively. The shoulder comprised 66-67% muscle, 24-27% bone and 4-6% fat. The slaughter weight had significant effects on the following characteristics: dressing yield, carcass measures and indices, subcutaneous fatness, meat colour, and muscle/fat ratio. The effect of gender was smaller: the female kids presented the highest fatness values for all parameters studied. Also, these animals displayed the lowest percentage of joints of extra class. The meat of female kids contained significantly less muscle and bone and a higher proportion of fat than that of male kids. The allometric analysis displays an early growth in the carcass measures and indices, fifth quarter, joints and bone proportion of shoulder. Internal and dissectible fats show a late growth. Principal component (PC) analysis was performed to study the relationship between carcass quality variables. The six first PC's explained about 85% of the total variability. The weight and yield of the carcasses were more effective to define the first PC. The projection of the carcass quality data in the first two PC's allowed distinguishing between carcass weight and carcass conformation groups, but not between gender and fatness.

Body composition and nutritional requirements of protein and energy for body weight gain of lambs browsing in a tropical semiarid region

This study evaluated body fat, protein and energy contents and nutritional requirements for body weight (BW) gain of lambs in tropical semiarid conditions. Thirty-two castrated Santa Inês 3-to-4-month old lambs (initial BW: 15.8 kg ± 1.4 kg) were used. Eight lambs were initially slaughtered to serve as the reference for initial body weight composition. The remaining 24 animals were placed in a randomized block with three treatments and eight replications. Each one of the eight experimental blocks consisted initially of three 15 kg lambs to which treatments (daily supplement levels: 0.0, 1.0, and 1.5% of body weight of a corn, soybean and minerals concentrate mixture adjusted for a daily 200 g BW gain at 1.5% level) were randomly assigned. As one of the lambs reached 30 kg all three were slaughtered. Body composition (per kg of empty body weight - EBW), ranged from 171.59 to 145.84 g protein, from 0.53 to 319.00 g fat, and from 2,06 to 3,90 Mcal energy, for lambs from 15 to 30 kg EBW, respectively. Net requirements for 200 g BW gain/day ranged from 25.99 to 22.09 g protein and from 0.311 to 0.591 Mcal energy for lambs from 15 to 30 kg EBW, respectively. Santa Inês lambs browsing in tropical semiarid regions require more protein and less energy than lambs raised in temperate regions or kept in feedlots in tropical areas, as reported in the literature.

Body composition and energy and protein requirements of grazing Nelore steers

This experimentwas carried out with the objective of determining the energy and protein requirements of grazing Nellore steers. Twenty four Nellore steers (average 371 ± 14 kg of BW and 26 months old) were used. Four steers were slaughtered at the beginning of the experiment (reference group), serving as a reference for the subsequent study. The remaining 20 animals were weighed and distributed in a randomized complete block design with four levels of supplementation offers: 0.0 (mineral mixture - control), 0.3, 0.6 and 0.9% BW, with five replications. The supplements, based on ground corn, soybean meal and/or urea, were previously balanced to achieve an average daily gain of 350, 650 and 850g, respectively, for the different levels of supplementation offers. The protein, fat and energy contents retained in the animal body were determined by regression equations of the logarithm of the protein, fat and energy in the animal body contents, in function of the logarithm of empty body weight (EBW). Net requirements of protein and energy for a gain of 1kg of EBW were obtained by deriving the prediction equations of the animal body content of protein, fat, or energy in function of the EBW logarithm. The net energy requirements for weight gain of Nellore steer can be obtained by the equation: NEg = 0.05764 × EBW0,75 × DEBWG0.8328. The following equation was obtained to estimate the retained protein (RP), in function of the average daily gain (ADG) and retained energy (RE): RP = 28.9199 + 85.7301 FBWG + 8.0669 RE. The net protein requirement for Nellore steers decreased as the body weight increased, with values of 174.62 and 163.10 g/kg EBG for animals of 300 and 450 kg BW, respectively.

Composição corporal e exigências de macrominerais para ganho de peso de caprinos em pastejo

An experiment was conducted to estimate the body composition and nutritional requirements of macrominerals for the weight gain of &frac12; Boer and &frac12; mixedbreed kid goats, in the phase of growth on pasture in the semi-arid region. The experiment was developed at ‘Nupeárido’ farm, in Patos, Paraíba State. Twenty-four kids were used, with average initial body weight of 15 kg, distributed into four treatments with increasing levels of concentrate supplementation (0, 0.5, 1.0 and 1.5% of body weight). The animals, maintained under semi-confinement system, received feeding supplementation in individual stalls when they were gathered daily. When one of the animals of each group reached 30kg of body weight, all other animals in the group were slaughtered after a 16-hour fast. Body composition varied from 15.36 to 17.17 g of Ca; 8.16 to 8.24 g of P; 1.00 to 1.42 g of Na, and 1.23 g of K per kg of empty body weight. The net requirements of Ca, P and Na varied, respectively, from 13.96 to 15.61 mg, 6.55 to 6.62 mg and 1.16 to 1.65 mg, and is of 0.98 mg of K by gram of weight gain for animals between 15 and 30 kg of body weight.

Body composition and net protein and energy requirements for weight gain of crossbred dairy cattle in grazing

The body composition and net protein and energy requirements for weight gain of 5/8 Hostein-Zebu crossbred cattle raised in Brachiaria decumbens Spaft pasture were evaluated. In total, 16 bulls with 10 months of age and body weight (BW) of 180 ± 19.95 kg were used. The animals were kept with free access to pasture or with restricted grazing (from 6 to 10 h). Four animals were slaughtered at the beginning of the experimental period to estimate the empty body weight (EBW) and the initial body composition of the remaining animals. The other animals were slaughtered at the end of the 84-day trial period. The logarithm equations of the protein and energy body content were adjusted according to the logarithm of the empty body weight EBW. From these equations, the net protein and energy requirements for weight gain were estimated. There was an increase in fat (from 37.17 to 59.08 g/kg EBW) and energy (from 1.68 to 1.94 Mcal/kg EBW) concentrations, with increase in body weight from 150 to 250 kg. The protein and energy requirements for gaining 1 kg of EBW increased with the increase in body weight or empty body weight. The relationship between fat concentration in gain and protein requirements also increased, indicating that as the BW or EBW increase, more fat deposition in the gain is observed.

Distribuição de gorduras internas e de descarte e componentes externos do corpo de novilhos de gerações avançadas do cruzamento rotativo entre as raças Charolês e Nelore

Foram avaliados os efeitos de heterose e grupo genético na distribuição das gorduras internas e de descarte e dos componentes externos do corpo de novilhos puros, Charolês (C) e Nelore (N), e mestiços de segunda (¾C × ¼N e ¾N × ¼C), terceira (5/8C × 3/8N e 5/8N × 3/8C) e quarta gerações (11/16C × 5/16N e 11/16N × 5/16C) de cruzamento terminados em confinamento. Em comparação à média dos puros, os novilhos de segunda geração apresentaram maior peso absoluto das gorduras renal, intestinal e total, resultando em heterose de 39,88; 43,96 e 31,80%, respectivamente. A gordura ruminal dos novilhos da quarta geração foi 41,48% maior que a média dos puros. Quando expressa em porcentagem do peso do corpo vazio (PCV), os animais da segunda geração foram superiores aos puros somente em relação à gordura intestinal, apresentando heterose de 28,06%. Os animais de quarta geração foram 21,67% inferiores aos puros quando a gordura de toalete foi expressa por 100 kg de PCV. Novilhos Charolês tiveram maior peso absoluto de gordura de descarte em relação aos novilhos Nelore (2,85 vs 1,30 kg). Nos novilhos ¾C × ¼N, a gordura intestinal foi maior que nos ¾N × ¼C, em pesos absoluto (10,15 vs 7,83 kg) e relativo (2,59 vs 2,02%). O peso de gordura ruminal nos animais 11/16N × 5/16C foi maior que nos 11/16C × 5/16N (6,93 vs 4,94 kg). A heterose para o peso relativo da cabeça foi significativa na terceira (-15,54%) e quarta (-13,12%) gerações de cruzamento, enquanto a heterose para o peso relativo das patas foi significativa apenas na terceira geração (-11,08%). O peso relativo das patas nos novilhos Charolês foi maior que nos Nelore (2,18 vs 1,88%). As gorduras não-integrantes da carcaça apresentam heterose significativa no cruzamento rotativo entre as raças Charolês e Nelore.

Developmental patterns of digestive enzyme activity in the stomach and pancreas of growing Jinhua and Landrace gilts

The activities of amylase, trypsin and lipase in pancreas and the activity of pepsin in cardiac mucosa were measured in Jinhua and Landrace gilts at 35, 80 and 125 days of age, respectively. Jinhua gilts had lower total trypsin and total pepsin activities compared with Landrace gilts (P<0.01), and lower pepsin activity (per g of cardiac mucosa) at 80 days (P<0.05) and 125 days of age (P<0.01). In contrast, Jinhua gilts had higher amylase activity (per g of pancreas) and lipase activity (per kg of empty body weight) compared with Landrace gilts (P<0.001), and higher total amylase activity at 35 days (P<0.05) and 125 days (P<0.01) of age. Jinhua gilts had higher lipase activity (per g of pancreas) at 35 days (P<0.05), 80 days (P<0.01) and 125 (P<0.001) days of age.

Órgãos internos e trato gastrintestinal de novilhos de gerações avançadas do cruzamento rotativo entre as raças Charolês e Nelore terminados em confinamento

Foram avaliados os efeitos de heterose e de grupo genético nos órgãos internos e no trato gastrintestinal de novilhos puros (Charolês - C e Nelore - N) e cruzados da segunda (G2) (3/4C 1/4N e 3/4N 1/4C), terceira (G3) (5/8C 3/8N e 5/8N 3/8C) e quarta (G4) (11/16C 5/16N e 11/16N 5/16C) gerações de cruzamento terminados em confinamento e abatidos com 23 meses de idade. Os animais cruzados da G2, G3 e G4 foram, respectivamente, 14,95; 17,25 e 18,46% superiores aos puros quanto ao peso de corpo vazio (PCVZ). A heterose para o rendimento de carcaça fria em relação ao PCVZ (RCFCVZ) foi positiva em todas as gerações. Os mestiços apresentaram menor peso relativo (ao PCVZ) de coração, pulmões e rins, de modo que a heterose foi significativa para peso de coração (-18,29%) e rins (-14,29%) na G3 e para pulmões (-13,45%) na G4. Novilhos mestiços apresentaram valores inferiores à média dos puros para todos os componentes do trato gastrintestinal quando o peso destes componentes foi expresso em relação a 100 kg de PCVZ ou de peso vivo ao abate (PVA), com exceção do rúmen na G2. A heterose retida foi positiva e significativa para PCVZ, RCFCVZ e para peso absoluto do fígado. Entretanto, foi negativa para a quantidade de sangue para os pesos de coração, intestino delgado + grosso e trato gastrintestinal quando expressos em relação a 100 kg de PCVZ e de PVA. Entre os animais puros, os novilhos Nelore tiveram maior RCFCVZ (57,09 vs 61,64%). O peso absoluto de rúmen, abomaso, intestino delgado + grosso e o trato gastrintestinal foram maiores nos novilhos Charolês em relação aos Nelore, o que também foi observado quando estes componentes foram expressos em relação ao PCVZ e PVA, com exceção para o intestino grosso + delgado. Estas diferenças explicam, em parte, o maior rendimento de carcaça dos novilhos Nelore.

Composição do ganho e exigências de energia e proteína para ganho de peso em bovinos Nelore puros e mestiços

Objetivou-se estimar a composição do ganho e as exigências de energia e proteína para ganho de peso em bovinos Nelore puros e mestiços. Utilizaram-se 60 bovinos machos (Nelore, F1 Nelore x Angus, F1 Nelore x Pardo-Suíço e F1 Nelore x Simental) não-castrados, com 10 a 11 meses de idade e peso médio inicial de 286, 309, 333 e 310 kg, respectivamente. O delineamento utilizado foi o inteiramente casualizado, com quatro grupos genéticos, submetidos a quatro níveis de concentrado na ração (30, 40, 60 e 70%). Três animais de cada grupo genético foram abatidos ao início do experimento e serviram como referência na determinação da composição corporal inicial. As exigências líquidas de proteína e energia para ganho de 1 kg de peso corporal vazio (PCV) foram estimadas pela equação Y' = a. b. X (b-1), em que a e b são os coeficientes das equações de regressão dos conteúdos de energia e proteína e X, o PCV dos animais. O teste de identidade de modelos não-lineares indicou não haver diferenças entre grupos genéticos para as exigências de energia e proteína para ganho de peso. Verificou-se decréscimo de 10,6% nas exigências de proteína e elevação de 37,8% nas exigências de energia para ganho de peso entre 250 e 550 kg, o que está relacionado à elevação do teor de gordura e à redução no teor de proteína com o acréscimo no PCV. As exigências líquidas de proteína e energia para ganho de peso foram estimadas em 143,5 g e 4,7 Mcal para o peso vivo de 450 kg.

Composição corporal e exigências nutricionais de proteína e energia para cordeiros Morada Nova

Este trabalho foi realizado objetivando-se determinar a composição corporal de proteína, gordura e energia e as exigências nutricionais de proteína e energia para mantença e ganho de peso de ovinos Morada Nova. Foram utilizados 30 cordeiros com peso vivo (PV) médio inicial de 15 kg. Para determinação da composição corporal, pela metodologia do abate comparativo, seis cordeiros (animais-referência) foram abatidos aos 15 kg, seis aos 20 kg (abate intermediário) e os demais foram distribuídos em seis grupos (um para cada dieta) de três animais, de acordo com a relação volumoso(V):concentrado(C): 40:60, 55:45 e 70:30. Os cordeiros em cada grupo foram abatidos quando o que recebia a dieta com maior teor de concentrado atingiu 25 kg de PV. A composição corporal variou de 181,53 a 178,74 g de proteína; 72,37 a 131,11 g de gordura e 1,81 a 2,34 Mcal de energia por kg de peso de corpo vazio (PCV). As exigências líquidas de ganho variaram de 222,30 a 218,6 g de proteína e de 3,30 a 4,28 Mcal de energia por kg de PV ganho. As perdas endógenas de nitrogênio foram de 0,332 g/kg0,75/dia. A exigência líquida de energia para mantença, estimada pela produção de calor em jejum, foi de 52,49 kcal/kg0,75 de PCV. As exigências de proteína e energia metabolizável para cordeiros dos 15 aos 25 kg de PV, com ganho de peso diário de 100 g, oscilaram de 53,46 a 60,19 g/dia e de 1,47 a 2,00 Mcal/dia, respectivamente.