Paulina Pogorzelska-Przybyłek

The Effect of Slaughter Season on the Fatty Acid Profile in Four Types of Fat Deposits in Crossbred Beef Bulls

The objective of this study was to determine the effect of slaughter season on the fatty acid profile in four types of fat deposits in crossbred (Polish Holstein Friesian Black-and-White×Limousine) beef bulls. The percentage share of fatty acids was determined by gas chromatography and were divided into the following categories of fatty acids: saturated (SFAs), unsaturated (UFAs), monounsaturated (MUFAs), polyunsaturated (PUFAs), desirable hypocholesterolemic (DFAs) and undesirable hypercholesterolemic (OFAs), n-3 and n-6. Perinephric fat was characterized by the highest SFA concentrations (59.89%), and subcutaneous fat had the highest MUFA content (50.63%). Intramuscular fat was marked by a high percentage share of PUFAs and the highest PUFA/SFA ratio. The slaughter season had a significant effect on the levels of C18:3, C20:4 (p≤0.01) and conjugated linoleic acid (p≤0.05). There was an interaction between the slaughter season and fat type for the content of C20:4 (p≤0.01) and C20:5 (p≤0.05). The results of this study show that beef from cattle slaughtered in the summer season has a higher nutritional value and more health-promoting properties.

Prediction of the carcass value of young Holstein-Friesian bulls based on live body measurements.

Abstract The aim of this study was to determine the suitability of ultrasound and zoometric measurements and visual muscle scoring for predicting the carcass value of 167 young Holstein-Friesian (HF) bulls. Zoometric and ultrasound measurements were performed and live muscle scoring was estimated before slaughter. After slaughter, hot carcass weight (HCW) was determined and carcasses were assigned to conformation and fat classes according to the EUROP system. Multiple regression equations were derived to estimate the weight, conformation and fatness of carcasses. HCW was estimated using the following equations: Ŷ = 1.507x1 + 1.103x2 + 4.043x3 + 5.53x4 + 0.379x5 + + 8.076x6 - 678.93 (R2=0.892; Sy = 16.28) and Ŷ = 2.525x4 + 0.579x7 + 0.451x8 - 134.17 (R2=0.943; Sy = 11.84); independent variables x1 - height at sacrum (cm); x2 - chest girth (cm); x3 - pelvic width (cm); x4 - pelvic length (cm); x5 - thickness of M. gluteo-biceps (mm); x6 - intravital muscle scoring (points); x7 - thickness of M. longissimus dorsi (mm); x8 - live weight (kg). Validation of the first regression equation revealed overestimation of HCW by 1.25% on average, while validation of the second equation revealed its underestimation by 1.85% on average. It was found that intravital muscle scoring and selected ultrasound and zoometric measurements of HF bulls can be used in formulating regression equations for predicting the carcass value of live animals. The proposed models enable predicting the carcass value of young bulls with satisfactory accuracy, thus contributing to an objective live beef cattle assessment

Carcass characteristics and meat quality of bulls and steers slaughtered at two different ages

Abstract This study was conducted to evaluate animal performance, carcase characteristics and meat quality of young bulls and steers (Charolais × Holstein-Friesian), fattened until 15 and 18 months of age. One half of 40 young bulls were castrated at 2 or 3 weeks of age. Starting at 7 months of age, they received grass silage supplemented with concentrates. At the end of the fattening period, the animals were slaughtered, and carcase quality and the quality of meat from Musculus longissimus thoracis (MLT) were evaluated. Bulls had a higher carcase dressing percentage, and their carcases had higher lean meat content than steers. MLT from steers had higher intramuscular fat (IMF) content (by 0.89%); it was less tough, more tender and palatable. IMF from bulls had higher concentrations of polyunsaturated fatty acids (PUFAs) and a higher n-6/n-3 PUFA ratio than IMF extracted from steer meat. Older animals had higher carcase quality than those slaughtered at 15 months of age, and slaughtering at a later age had no negative influence on meat quality.

Effects of rearing system and feeding intensity on the fattening performance and slaughter value of young crossbred bulls

Abstract The aim of this study was to determine the effects of rearing system and feeding intensity on the fattening performance and slaughter value of 38 young crossbred bull calves. The calves were raised naturally with nurse cows (NC) or were fed milk replacer (MF) until 150 days of age. During the rearing period the NC calves were healthier and had higher average daily gain (by 0.15 kg) compared to the MF calves. After a 30-day transition period, the animals were fattened in intensive (I) and semi-intensive (SI) systems from 181 to 560 days of age. During the fattening period, the bulls were fed ad libitum a total mixed ration (TMR) composed of grass silage and concentrate. The concentrate to silage ratio, on a DM basis, was 25:75 (SI) and 40:60 (I). The MF calves had lower BW at the end of the fattening period compared to the NC calves but the rearing system had no effects on daily gain during the fattening period. Compensatory growth was not observed during fattening. During the fattening period, a higher proportion of concentrate in the ration contributed to higher feed intake, higher feed efficiency and more desirable carcass characteristics. Three-rib cuts from the carcasses of the I bulls had significantly (P<0.05) higher fat content and lower bone content compared to the carcasses of the SI bulls. The longissimus thoracis muscle of the I bulls had higher (P<0.01) intramuscular fat content compared to the SI bulls.

Estimation of the intramuscular fat content of m. longissimus thoracis in crossbred beef cattle based on live animal measurements

The objective of this study was to determine the usefulness of live animal measurements in estimating the intramuscular fat (IMF) content of m. longissimus thoracis (MLT) in beef cattle. Live animal measurements were performed in young crossbred bulls (96) and steers (59), the offspring of Holstein-Friesian (HF) cows and beef bulls (Limousin, Hereford and Charolais), at the end of the fattening period. The content of intramuscular fat was determined in samples from MLT by chemical analyses. A prediction model was developed by stepwise regression. In the validation model, the values of R2=0.74, RMSE=0.37% were determined. The results indicate that selected biometric (chest width, chest girth) ultrasound measurements (thickness of subcutaneous rump and back fat) and selected blood parameters (triglycerides) can be used to predict IMF content with satisfactory precision and accuracy. The analyzed parameters could constitute a valuable tool in the process of selecting beef quality traits and determining the slaughter value of young beef cattle.

Impact of early castration and health status on the performance of Holstein-Friesian and beef crossbred calves

Abstract Introduction: This article presents the analysis of the correlation between the category and health status of calves and the results of their rearing and levels of selected blood parameters. Material and Methods: The study included 105 Polish Holstein-Friesian and beef (Limousine, Charolaise and Hereford) crossbred calves. Young bulls were purchased at the age of two to four weeks. The animals underwent quarantine, were dehorned, and 46 young bulls were castrated. The germ horns were removed by burning out. Castration was carried out with a bloodless method using a rubber band. The calves were kept in groups and fed a milk replacer administered via teats from automated milk-feeding stations. After the period of milk feeding, the calves were fed grass silage ad libitum and a concentrate at 2.5 kg/animal/day. The calves were weighed every two weeks. Blood for analyses was sampled at 43 d of age. Results: After the rearing period finished at the age of six months, young bulls and steers had similar body weights (176.17 and 176.55 kg) and approximate average daily weight gains from birth (0.756 and 0.767 g/day). The healthy calves at six months of age weighed 180.47 kg, whereas the animals which at least once suffered from some diseases during rearing were lighter by approx. 30 kg (P ≤ 0.01). A statistically significant (P ≤ 0.01) difference was found for the count of red blood cells and white blood cells. In comparison with healthy individuals, the diseased animals had less RBC (8.33 and 9.42 1012/L respectively) and more WBC (27.03 and 12.26 109/L respectively). Conclusion: Castration of young bulls did not have any impact on the results of rearing and health status of the calves. The magnitude of the analysed parameters depended on the health status of the calves. Thus RBC and WBC parameters may be used to predict the health status of calves during rearing.

Effect of fattening intensity on the fatty acid profile and mineral content of meat from Holstein-Friesian bulls

Diets high in saturated fatty acids (SFAs) and n-6 polyunsaturated fatty acids (PUFAs) at the expense of n-3 PUFAs have been shown to increase the risk of cardiovascular disease, obesity and cancer. Animal fat is considered to be the major source of unhealthy saturated fats. However, beef fat has a high nutritional value owing to the presence of minerals, PUFAs, vitamins and selected protein fractions. The aim of this study was to determine the effect of fattening intensity on the fatty acid profile and mineral content of meat from Holstein-Friesian bulls. Holstein-Friesian bulls aged 11 to 19 months were fattened under semi-intensive (SI, 10 animals) and intensive (I, 10 animals) systems. The bulls were fed maize silage, rapeseed meal and premix ad libitum. The diets for group I animals were supplemented with 2.5 kg ground triticale provided in an automatic feeding station. Meat samples were collected from m. longissimus dorsi (MLD). The samples were mineralized and assayed for mineral content. Fat was extracted from each sample, and the fatty acid profile of beef was determined by gas chromatography. Dietary supplementation with ground triticale increased the average daily gains of bulls and carcass dressing percentage, and contributed to higher carcass conformation and fat cover scores. Beef was found to be a rich source of valuable mineral compounds. The meat of group I animals was characterized by higher potassium levels and lower sodium levels, which points to its higher nutritional value. Semi-intensive (SI) fattening increased PUFA concentrations and decreased the n-6/n-3 PUFA ratio in beef.