Monika Sobczuk-Szul

The effect of carcass conformation class (EUROP system) on the slaughter quality of young crossbred beef bulls and Holstein-Friesians.

Abstract The objective of this study was to determine the effect of genotype and carcass conformation class on the slaughter quality of 200 young bulls, including 108 crossbred beef bulls and 92 Holstein- Friesians (HF), aged 21-22 months, selected in the lairage. The lean meat content was estimated and body measurements were taken before slaughter. After slaughter, the carcasses were graded according to the EUROP system, and carcass quality parameters were determined. Intramuscular fat was extracted from samples of m. longissimus dorsi, and the fatty acid profile of extracted fat was determined by gas chromatography. 61.11% carcasses of crossbred beef bulls were graded in the conformation class R, and 56.53% carcasses of Holstein-Friesians were classified as O. The majority of carcasses belonged to fat class 2, which was not consistent with intramuscular fat content. Within the same conformation classes, crossbred beef bulls were characterized by higher slaughter quality than Holstein-Friesian bulls. Meat from hybrid beef bulls had a higher (by 0.42% on average) content of fat with a more desirable composition. Since the population size of beef cattle will probably not increase in the nearest future, efforts should be continued to optimize the production of high-quality beef from dairy cattle herds. Streszczenie Badano wpływ genotypu i klasy uformowania tuszy na wartość rzeźną 200 buhajków. W magazynie żywca wybrano sztuki w wieku 21-22 miesięcy, z czego 108 były to mieszańce mięsne a 92 holsztyno- fryzy (ho). Przed ubojem oceniano ich umięśnienie i wykonano pomiary zoometryczne ciała. Po uboju sklasyfikowane tusze według systemu EUROP poddano szczegółowej ocenie wartości rzeźnej. Z próbki mięśnia najdłuższego grzbietu wyekstrahowano tłuszcz śródmięśniowy, w którym metodą chromatografii gazowej określono udział kwasów tłuszczowych. W klasyfikacji EUROP tusze buhajków mieszańców mięsnych w 61,11% uzyskały klasę uformowania R, a tusze holsztyno-fryzów w 56,53% oceniano jako O. W ocenie otłuszczenia dominowała klasa 2. i ocena otłuszczenia nie była zbieżna z zawartością tłuszczu śródmięśniowego. W obrębie jednakowych klas uformowania, mieszańce mięsne charakteryzowały się wyższą wartością rzeźną, w porównaniu z holsztyno-fryzami. Ponadto mięso ich zawierało średnio o 0,42% więcej tłuszczu o korzystniejszym składzie procentowym. Wobec braku realnych perspektyw na szybkie zwiększenie się wielkość populacji bydła ras mięsnych, należy prowadzić badania w kierunku opracowania metod optymalnej produkcji wołowiny o podwyższonej jakości w oparciu o stada mleczne.

The Effect of Body Energy Reserve Mobilization on the Fatty Acid Profile of Milk in High-yielding Cows

We investigated the effect of the amount of body condition loss in the dry period and early lactation in 42 high-yielding Holstein-Friesian cows on milk yield and the share of fatty acids in milk fat. Energy reserves were estimated based on the body condition scoring (BCS) and backfat thickness (BFT). Milk yield and milk composition were determined over 305-d lactation. From d 6 to 60 of lactation, the concentrations of 43 fatty acids in milk fat were determined by gas chromatography. Cows were categorized based on body condition loss from the beginning of the dry period to the lowest point of the BCS curve in early lactation into three groups: low condition loss group (L) ≤0.5 points (n = 14); moderate condition loss group (M) 0.75 to 1.0 points (n = 16) and high condition loss group (H) >1.0 points (n = 12). Cows whose body energy reserves were mobilized at 0.8 BCS and 11 mm BFT, produced 12,987 kg ECM over 305-d lactation, i.e. 1,429 kg ECM more than cows whose BCS and BFT decreased by 0.3 and 5 mm, respectively. In group H, milk yield reached 12,818 kg ECM at body fat reserve mobilization of 1.3 BCS and 17 mm BFT. High mobilization of body fat reserves led to a significant (approx. 5%) increase in the concentrations of monounsaturated fatty acids-MUFA (mostly C18:1 cis-9, followed by C18:1 trans-11), a significant decrease in the levels of fatty acids adversely affecting human health, and a drop in the content of linoleic acid, arachidonic acid and docosahexaenoic acid in milk fat. In successive weeks of lactation, an improved energy balance contributed to a decrease in the concentrations of unsaturated fatty acids (UFA) and an increase in the conjugated linoleic acid (CLA) content of milk fat.

The Effect of Slaughter Weight and Fattening Intensity on Changes in Carcass Fatness in Young Holstein-Friesian Bulls

The objective of this study was to determine the effect of body weight (BW) at slaughter and fattening intensity on carcass fatness and meat fatty acid profile in young Holstein-Friesian bulls. One-hundred bulls fattened on two levels of intensity a semi-intensive (SI) and an intensive (I) were used. Fattening was carried out to BW of 500, 550, 600, 650 and 700 kg. Live ultrasound measurements were performed to determine back fat thickness. Carcass dressing percentage, carcass conformation and fatness, intramuscular fat content of m. longissimus dorsi and fatty acid profile (by gas chromatography) were determined after slaughter. Intensively fattened bulls were characterised by a greater carcass dressing percentage – by 1.17% on average, greater carcass conformation scores, greater external fat thickness and a greater intramuscular fat content than bulls SI fattened. Fat from intensively fattened bulls contained higher levels of polyunsaturated fatty acids (PUFAs) – by 0.96/100 g on average. Semi-intensive fattening contributed to a decrease in the n-6/n-3 PUFA ratio and to a significant increase in the concentrations of C18:2 and C20:4 fatty acids. Regardless of the fattening intensity, the n-6/n-3 ratio was greater in heavier animals. The best results were achieved when young Holstein-Friesian bulls were fattened intensively to BW of 650 kg.

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.

Fatty acid profiles of intramuscular, intermuscular, external and internal fat in Polish Holstein-Friesian × Hereford bulls and steers fed grass silage-based diets supplemented with concentrates

This paper determined the impact of gender and feeding intensity on the profile of fatty acids in different types of fat deposits. The studies were conducted with 20 young bulls and 20 steers, which were Polish Holstein-Friesian and Hereford crossbreds fattened intensively – grass silage ad libitum and concentrate covered 50% of the net energy requirement in fattened cattle or semi-intensively – concentrate covered 30% of the net energy. The fatty acid profile in intramuscular, intermuscular, external and internal fat was determined. The content of intramuscular fat was lower (P < 0.001) in the longissimus muscle in the bulls (1.74%) than in the steers (3.71%). In fat of steers, the proportion of monounsaturated fatty acids was higher whereas in fat of bulls, the content of polyunsaturated fatty acids was higher. Generally the impact of the location of fat depots on the profile of fatty acids was statistically significant (P < 0.001) but there was no effect of feeding intensity.

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.

Fattening performance of crossbred (Polish Holstein-Friesian x Hereford, Limousin or Charolais) bulls and steers offered high-wilted grass silage-based rations

7 CHILEAN JOURNAL OF AGRICULTURAL RESEARCH 76(1) JANUARY-MARCH 2016 3 ULY-SEPTEMBER In Poland beef cattle are usually fed high-wilted grass silage offered ad libitum and supplemented with concentrate, whereas ‘Limousin’, ‘Charolais’ and ‘Hereford’ bulls are the most frequently crossed with dairy cows to produce beef hybrids. The aim of this study was to determine the fattening performance of hybrids produced by crossing ‘Polish Holstein-Friesian’ (PHF) cows with ‘Hereford’ (HH), ‘Limousin’ (LM) and ‘Charolais’ (CH) bulls, fed silage made from high-wilted grass and supplemented with a small amount of concentrate, depending on sire breed and category. The experimental materials comprised 24 bulls and 24 steers, including 8 PHF × HH, 8 PHF × LM and 8 PHF × CH crosses with initial body weight of approximately 300 kg in each group. The animals were fed grass silage with a DM content of 417 g kg-1, supplemented with concentrate at 35 g DM kg-1 W0.75, for 250 d. Steers were characterized by higher total DM intake per unit of metabolic body weight (P < 0.05): 92.8 vs. 87.0 g; 94.1 vs. 84.6 g; 88.6 vs. 87.0 g (PHF × HH; PHF × LM; PHF × CH, respectively) and bulls – by higher average carcass weight gains (P < 0.01): 700 vs. 631 g; 654 vs. 579 g; 633 vs. 574 g and carcass dressing percentage (P < 0.01): 60.0 vs. 56.4%; 60.2 vs. 58.9%; 60.2 vs. 56.6% (PHF × HH; PHF × LM; PHF × CH, respectively) and better (P < 0.01) silage DM, total DM, crude protein, and net energy utilization. Sire breed had no significant effect on the analyzed parameters of fattening performance but numerically PHF × HH crosses had the highest productivity parameters.

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.