Magali Floriano da Silveira

Características da carcaça de novilhos de gerações avançadas do cruzamento alternado entre as raças Charolês e Nelore, terminados em confinamento

The objective of this work was to evaluate the carcass characteristics of feedlot finished steers, straightbreds (Charolais - C and Nellore - N), and crossbreds from second (G2) (¾C ¼N and ¾N ¼C), third (G3) (5/8C 3/8N and 5/8N 3/8C) and fourth (G4) (11/16C 5/16N and 11/16N 5/16C) generations of rotational crossbreeding. Crossbreds showed higher slaughter, hot and cold carcass weights than the average of the purebreds, being the total heterosis, respectively, 14.95; 18.72 and 18.39% in G2, 19.98; 24.16 and 24.59% in G3 and, 18.38; 22.55 and 22.88% in G4. Total heterosis for the three characteristics followed the fluctuation of individual heterozygosis. Heterosis for hot and cold carcass dressing percentage was significant in all generations, being the retained heterosis, respectively, 3.22 and 3.71%. Carcass chilling loss in G2 did not differ from purebreds, but was significantly lower in G3 (-16.73%) and G4 (-12.84%). For carcass physiological maturity, heterosis was negative and significant in G3 and G4. Subcutaneous fat thickness was higher for the crossbreds of the three generations, however, was only significant in G4. For the characteristics related to carcass muscling, heterosis was significant in the three generation for conformation and Longissimus dorsi area, for cushion thickness and arm perimeter, although positive in the three generations, reached significance only in G3 and G4, being the retained heterosis, respectively, 8.09; 11.33; 7.45 and 5.95%. The characteristics related to corporal development showed significant heterosis in all generations, being the retained heterosis 8.55; 5.73 and 4.99%, respectively, for carcass, leg and arm length. The proportion of commercial cuts of the carcass was not affected by heterozygosis, but for their absolute values, heterosis was significant following the carcass weight behavior.

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

The objective of this trial was to investigate the effect of heterosis and genetic group on the yield and weight of internal organs and gastrointestinal tract (GIT) of feedlot purebred (Charolais C and Nellore N) and crossbred steers from second (G2) (¾C ¼N and ¾N ¼C), third (G3) (5/8C 3/8N and 5/8N 3/8C) and fourth (G4) (11/16C 5/16N and 11/16N 5/16C) generations of rotational crossbreeding slaughtered at 23 month of age. Crossbred steers from G2, G3 and G4 had, respectively, 14.95, 17.25 and 18.46% higher empty body weight (EBW) than that from purebred animals. A positive heterosis for cold carcass yield expressed as a proportion of EBW (CCYEBW) was observed in G2, G3, and G4. Weights of heart, lungs, and kidneys adjusted for EBW were lower on crossbred compared to purebred steers; the heterosis was significant for the weights of heart (-18.29%) and kidneys (-14.29%) in G3 and for that of lungs (-13.45%) in G4. Weights of all organs of the GIT either expressed as 100 kg of EBW or as proportion of slaughter body weight (SBW) were lower on crossbred than on purebred steers with the exception of rumen weight in G2. Retained heterosis was positive and significant for EBW, CCYEBW and liver weight. However, it was negative for amount of blood and weights of heart and small plus large intestines when expressed as 100 kg of EBW and SBW. Within purebred animals, N showed greater CCYEBW (61.64%) than C (57.09). Conversely, weights of rumen, abomasum, small plus large intestine, and GIT were all higher on C than N steers; excepting for small plus large intestine, the same was observed when weights of the remaining GIT components were expressed as proportion of EBW and SB. These differences partially explain the increased carcass yield on N steers.

Produção e composição do leite de vacas de quatro grupos genéticos submetidas a dois manejos alimentares no período de lactação

The objective of this work was to evaluate the production and composition of milk of beef cows of four genetic groups, including Charolais (C), Nellore (N), CN crossbreds daughters of C bulls, and NC crossbreds, daughters of N bulls, maintained on native pasture and submitted to different managements during pre-weaning: supplemented with rice bran (.7% of the body weight) and weaned at 42 or 63 days postpartum, or non supplemented and weaned at 63 days. The cow age varied from 3 to 12 years, being classified as: first calf, young, adult and old cows. The data were submitted to variance analysis, the statistic model included management, cow genetic group, cow age and period effects and the interactions among these factors. Lactose and fat contents were not influenced by the factors studied. There was a significant interaction between cow age and period for milk production and between management and cow age for protein content. Supplemented cows showed higher milk production (3.85 vs 3.25 L/day), total dry extract content - EST (12.18 vs 11.83%) and nonfat dry extract content - ESD (8.75 vs 8.57%). The milk production declined as the lactation period advanced, and the reduction was more accentuated in the non supplemented cows. CN crossbred cows produced more milk (4.17 L/day) than the straigthbreds, not differing from the NC crossbred (3.76 L/day). N cows showed milk production similar to the C cows, respectively, 3.16 and 3.11 L/day. However, N cows milk was of better quality, including protein (3.16 vs 2.86%), EST (12.52 vs 11.46%) and ESD (8.87 vs 8.49%). Adult cows showed higher ESD content, followed by the young cows, first calf and old cows, being 8.86; 8.62; 8.62 and 8.54%, respectively.

Ingestive behavior of feedlot finished young bulls fed different concentrate levels in the diet

This study was developed to evaluate the ingestive behavior of beef cattle finished in feedlots with different concentrate levels in the diet. Sixteen bulls fed 22, 40, 59, or 79% of concentrate in the diet were assigned to a complete randomized design, with four replicates each. The supplied diets were isoproteic and the roughage used was corn silage. Data collection was carried out during the finishing period, with a total of six days. The time given to food intake, rumination, the number of bouts per meal and neutral detergent fiber rumination efficiency decreased linearly as the concentrate levels in the diet increased. Idle time increased linearly accordingly to the increment of concentrate in the diet. The animals have greater feed intake and rumination efficiency when fed higher levels of concentrate (79%).

Composição física da carcaça e aspectos qualitativos da carne de bovinos de diferentes raças alimentados com diferentes níveis de energia

The objective of this trial was to study the physical composition of carcass and the qualitative characteristics of the meat of 16 finishing young bulls, eight Aberdeen Angus (AA) and eight Hereford (HE), fed diets with two energy levels (lower: 3.07 Mcal/kg of digestible energy - 12% of concentrate; or higher: 3.18 Mcal/kg of digestible energy - 32% of concentrate). Animals were feedlot fed since 9 months of age and an average body weight of 220.31 kg and were slaughtered when the estimate carcass weight reached at least 190 kg. A completely randomized design with a 2 x 2 factorial arrangement of treatments (two breeds vs. two energy levels) was used. Within breed, meat from HE showed the lowest loss of liquid during thawing and cooking. Meat from HE animals also showed the greatest tenderness when evaluated either by a panel or by the Shear force technique. Animals fed the higher energy diet had greater proportion of muscle, lower loss of liquid at thawing (2.54 vs. 7.22%), and a more tender meat (Shear force) than those fed the lower energy diet. A significant interaction was observed between breed and energy level for both meat flavor and color; AA bulls fed the higher energy diet had meat with greater flavor and better color.

Partes não-integrantes da carcaça de tourinhos alimentados com diferentes níveis de concentrado na dieta

The objective of this trial was to evaluate the non-integrant body components of the carcass from young bulls slaughtered at 14-16 months of age, fed different concentrate levels in the diet. The animals were feedlot finished until reaching 400 kg of body weight. Sixteen bulls were randomly distributed into four treatments: 22; 40; 59 or 79% concentrate in the diet. The initial average age and weight were 9.3 months and 192.4 kg, respectively. The empty body weight (EBW) and carcass dressing ajusted for empty body weight were similar among the different concentrate levels. The increase in the concentrate level in the diet promoted linear decrease for intestine absolute weight, and linear increase for ruminal and abomasum absolute fat weight. When the components were expressed as adjusted EBW values and slaughter weight (SW), linear increases were observed for weight of feet, heart, intestine, trim fat, ruminal fat, gastrintestinal tract content and internal fat, and linear decreases were observed for weight of head and omasum as the concentrate level increased. The response of the abomasum weight according to the concentrate level was quadratic, with the minimum values estimated for the concentrate levels of 68.0, 66.7 and 69.2%, in relation to the absolute weight, adjusted for EBW and SW, respectively. The increase in the concentrate level from 22 to 79% increased the ajusted weights of gastrintestinal tract content and internal fat; however, it did not affect the total internal organs, empty body weight and carcass dressing ajusted for empty body weight of bulls slaughtered at 14-16 months of age with 400 kg.

Efeitos da frequência de fornecimento do volumoso e concentrado no comportamento ingestivo de vacas e novilhas em confinamento

ABSTRACT - The present study was conducted with the objective of evaluating the influence of frequency ofroughage and supplement supply and/or animal category on the ingestive behavior of cattle. Sixteen heifers and sixteencows, with average initial age of 20 and 66 months and average initial weight of 338 and 432 kg, respectively, were used.Treatments were represented by the frequencies of roughage and concentrate supply: 2 R/C – roughage and concentratetwo times per day; 1 R/C – roughage and concentrate one time per day; 1 R/2C – roughage one time per day and concentratetwo times per day; 1 R/3 C – roughage one time per day and concentrate three times per day, offered to cows and heifers.Diet was composed of 60% maize silage and 40% concentrate, on a dry matter basis (DM). The complete randomizedexperimental design was used, with a 4 × 2 factorial arrangement (frequencies × category). The data were submitted tovariance analysis and averages were compared by “t” test. The interaction between supply frequencies and animal categorywas significant for rumination and idle times, efficiencies of dry matter rumination and of neutral detergent fiberrumination, number of ruminated bolus and daily time of chew. Heifers showed longer idle periods and daily time of chewwhen compared with cows that received food once in a day. Duration of feed intake did not vary with frequencies. Cowsshowed longer period of feed intake and ingestive rate in relation to heifers (4.38 vs. 4.09 hours and 2.91 vs. 2.35 kgof DM/hour of intake, respectively). The increase in food frequency stimulated animals to intensify feed intake at themoment of supply.Key Words: animal category, chews, food handling, food intake, idleness, rumination

Órgãos vitais e trato gastrintestinal de vacas de descarte mestiças Charolês x Nelore abatidas com pesos distintos

The objective of this experiment was to study the development of vital organs and gastrointestinal tract of culling crossbred cows from the second (G2: 3/4Charolais (C) Nellore (N) and 3/4NC) and third (G3: 5/8CN and 5/8NC) generations of C x N rotational crossbreeding. Animals were feedlot finished and slaughtered with 465 (T465), 507 (T507), and 566 kg (T566) of body weight (BW). At the beginning of the trial, age, BW, and body condition averaged respectively, 8.5 years, 388.6 kg and, 2.35 points. Animals were fed a 48:52 forage:concentrate ratio diet containing 12.5% crude protein and 2.99 Mcal of digestible energy per kg of dry matter. Liver showed the greatest development among the studied organs. Lungs and spleen showed high development until animals reached 507 kg BW (T507) but reduced at 566 kg BW (T566). Increasing slaughter weight reduced the proportion of internal organs and gastrointestinal tract in the total BW and empty body weight (EBW). G3 animals had heavier reticulum-rumen and stomach (reticulum-rumen+omasum+abomasum) (14.29 vs. 12.30 kg and 24.43 vs. 22.28 kg, respectively) compared to G2 cows. However, when expressed as proportion of BW and EBW only the reticulum-rumen weight differed between G2 and G3 cows. The greater contribution of C in the genotype resulted in increased volume of blood and development of lungs and all vital organs together when expressed as proportions of EBW.

Carcass and meat characteristics from young Devon steers finished in different feeding systems

Avaliaram-se as caracteristicas de carcaca e da carne de novilhos Devon terminados em confinamento, em pastagem temperada (pastagem de azevem -Lolium multiflorum Lam) ou em pastagem tropical (milheto, Pennisetum americanum (L.) Leeke + capim-papua, Bracharia plantaginea). No inicio da terminacao, os novilhos apresentaram em media 320 kg e 15 meses de idade. Os animais em confinamento foram alimentados com relacao volumoso:concentrado de 60:40 e abatidos com pesos semelhantes, de 388,3; 391,5 e 375,8 kg, respectivamente. A terminacao em pastagem tropical elevou a idade ao abate de 17 para 19 meses, como resultado do menor ganho de peso medio diario observado em relacao ao confinamento e a pastagem temperada. O sistema de alimentacao nao influenciou os pesos de carcaca quente e fria, nem seus rendimentos, mesmo que as carcacas dos animais terminados em pastagem tropical tenham apresentado maior quebra ao resfriamento em comparacao aos da pastagem temperada. A espessura de gordura subcutânea e a conformacao nos animais terminados em pastagem temperada foram maiores que naqueles terminados em pastagem tropical, enquanto os animais terminados em confinamento mantiveram-se em posicao intermediaria. Animais terminados em pastagem tropical apresentaram carcacas com maior porcentagem de ossos e menor porcao comestivel/osso. Os animais terminados em pastagem temperada apresentaram carcacas com maior espessura de coxao em relacao aqueles do confinamento. A carne dos animais terminados em pastagem temperada foi mais escura, apresentou maior forca ao cisalhamento e textura mais grosseira, com menor maciez, avaliada pelo painel de degustadores, em comparacao a carne daqueles terminados em confinamento ou em pastagem tropicale. Animais terminados em pastagem tropical apresentam carne menos palatavel que a de animais terminados em confinamento.

Composição física da carcaça e qualidade da carne de novilhos Charolês e Nelore que receberam diferentes proporções de concentrado na dieta

Avaliaram-se a composicao fisica da carcaca e a qualidade da carne de 22 novilhos contemporâneos, com media de idade de 22 meses, das racas Charoles ou Nelore, terminados em confinamento, e que receberam diferentes proporcoes de concentrado na dieta. A fracao volumosa da dieta foi composta pelas silagens de milho e sorgo em partes iguais. Os animais foram distribuidos em tres tratamentos constituidos por 35, 50 ou 65% de concentrado na materia seca. Nao houve efeito (P>0,05) da porcentagem de concentrado na dieta sobre a composicao fisica da carcaca. A proporcao de inclusao do concentrado influenciou (P=0,0013) positivamente a maciez da carne, aumentando em 0,026 pontos a cada ponto percentual de aumento do concentrado. As demais caracteristicas qualitativas da carne nao foram influenciadas (P>0,05) pelo aumento do concentrado na dieta. A carne dos novilhos Charoles apresentou textura mais fina, 4,15 x 3,14 pontos, foi mais macia, 6,85 x 5,71 pontos, mais suculenta, 7,17 x 5,77 pontos, e apresentou menor resistencia das fibras ao cisalhamento, 3,79 x 5,79kgF. A carcaca dos novilhos Charoles apresentou maior deposicao muscular, 65,5 x 61,5%, e a dos novilhos Nelore apresentou maior percentagem de gordura, 23,3 x 20,3%.