Content and gain of macro minerals in the empty body and body tissues of growing bulls

This research aimed to generate basic data for specifying the macro mineral requirements of beef bulls. Hence, the contents of the macro minerals calcium, phosphorus, sodium, potassium, sulfur, and magnesium in the empty body and body tissue fractions of growing Fleckvieh (German Simmental) bulls with 120-780 kg live weight were determined. Results were used to calculate mineral gain rates in bulls within a wide weight range from 100 to 800 kg live weight. Calcium and phosphorus represented the largest shares in the animals' bodies. Body mineral content changed during animal growth due to progressing bone mineralization and increasing amounts of fat in all body tissues. Peak mineral gain rates were observed for calcium, phosphorus, and magnesium during the 200-400 kg live weight range. The gain rates of sodium, potassium, and sulfur declined steadily during cattle growth. The provided data allow to adjust the existing values of net mineral requirements of growing Fleckvieh bulls within the factorial requirement calculation method.

[Prevalence of metatarsal growth plate lesions in Swiss fattening bulls]

INTRODUCTION

The prevalence of osteochondral changes in the metatarsal growth plates of fattening bulls was investigated. Plantarodorsal radiographic views of the metatarsal region of 204 hind legs from 102 slaughtered fattening bulls were taken. Radiographic lesions in metatarsal growth plates were confirmed in selected cases using computed tomography (n=14) and histology (n=6). Radiographic criteria for growth plate lesions were axis deviations between the metatarsal bones and the digit, radiolucencies in the growth plate, increased bone density in the metaphysis, irregularities of the growth plate and marginal osteophytes («lipping»). The individual lesions were categorised as present/absent or 1 = slight, 2 = distinct, and 3 = severe. A weighted sum of these radiographic changes was generated for each growth plate and for each animal, and used for statistical analysis of the associations between husbandry factors and the occurrence of lesions. Almost all of the metatarsal bones had signs of osteochondral changes on the radiographs of the growth plates. The most common lesions were lipping (99,5 %), increased bone density in the metaphysis (66,6 %) and radiolucencies in the growth plates (64,1 %). Computed tomography and histology revealed hyperplasia of the margins of the epiphysis and metaphysis, focal increase in bone deposits accompanied by incomplete ossification and irregular and widened cartilage columns of the growth plate. There were statistically significant associations between the weighted radiographic changes and slaughter weight, average daily weight gain, husbandry practices and production label. The prevalence of radiographic lesions indicative for osteochondrosis of the metatarsal growth plates of fattening bulls slaughtered at a local abattoir was high. The extent to which the distinct and severe lesions are associated with reduced production and obvious clinical lameness requires further study.

Body composition and composition of gain of growing beef bulls fed rations with varying energy concentrations

Data on chemical body composition of cattle serve as a basis for recommendations on energy and nutrient requirements. Relevant data of growing dual-purpose Fleckvieh (German Simmental) bulls are scarce and originate from old trials, covering low rates of gain and live weights. Hence, the aim of the study was to analyze the body tissue distribution, chemical composition, and composition of body weight gain of growing Fleckvieh bulls within a 120–780 kg live weight range. Results showed that body composition changed during growth but was not affected by dietary energy concentration. Changes in body composition were characterized by increasing shares of fat tissue and ether extract. Body tissues as blood, organs, gastrointestinal tract, and bone proportionately decreased during growth, while muscle and tendon proportions remained constant. The bulls featured enhanced growth potential and high muscle and protein gain throughout the described weight range. The requirements for metabolizable protein in relation to energy decrease with increasing live weight of the animals.

Metabolizable amino acids and energy requirements of Nellore and crossbred Angus × Nellore bulls fed rations of different crude protein concentrations

Growth rate of cattle depends on their genetic makeup and nutrient intake. Moreover, increased growth rate may lead to increased amino acid (AA) requirements. Therefore, we evaluated the AA content of the empty body and estimated the net AA and energy requirements of purebred and crossbred beef bulls fed rations of different dietary CP concentrations. We performed a comparative slaughter experiment with 24 Nellore and 24 Angus × Nellore (A × N) bulls (8 months; initial shrunk BW: Nellore = 208.0 ± 12.78 kg; A × N = 221.9 ± 14.16 kg). Eight bulls (four Nellore and four A × N) were designated as the reference group, eight bulls (four Nellore and four A × N) were fed to maintenance level and 32 bulls (16 Nellore and 16 A × N) were fed ad libitum. The 32 bulls fed ad libitum were distributed using a completely randomized design in a 2 × 3 factorial scheme with two genetic groups (Nellore or A × N) and three dietary CP contents (100, 120 or 140 g CP/kg DM), being four groups with five bulls and two groups with six bulls. The experimental period lasted for 224 days. There were no interactions (P ≥ 0.056) between the dietary CP contents and genetic groups for any of the response variables. The dietary CP contents did not affect (P ≥ 0.062) the AA content in the empty body (g/kg empty BW [EBW]), with exception for Tryptophan (P = 0.027, linear effect). The dietary CP contents did not affect (P ≥ 0.051) AA content in the empty body (g/100 g of CP), with exception for Alanine (P = 0.013) that responded quadratically to dietary CP increase. The equations to estimate the net Lysine (Lys) and Methionine (Met) requirements (g/100 g of CP) were: Lys = 5.1 × EBW^0.0594 and Met = 1.7 × EBW^0.0255. Metabolizable Lys and Met to metabolizable energy (ME) ratios decreased as bulls EBW increased. Also, the metabolizable protein to ME ratio decreased as bulls EBW increased. In conclusion, the present study provides useful information regarding net and metabolizable requirements of AA of purebred and crossbred beef bulls. In the future, after the validation of the equations, these results can be used to calculate the AA requirements for growth of purebred and crossbred beef bulls. Nevertheless, it is important to highlight that the small sample size was one limitation of this present experiment.

Influence of dietary energy concentration and body weight at slaughter on carcass tissue composition and beef cuts of modern type Fleckvieh (German Simmental) bulls

A feeding and slaughter experiment was conducted to evaluate the carcass tissue composition and meat quality of growing modern type Fleckvieh (German Simmental) bulls. For the study, 72 bulls were customary reared and for the fattening period allocated to a normal energy and a high energy treatment group with 11.6 and 12.4 MJ ME/kg DM, respectively. Bulls were slaughtered in a serial slaughter trial with final live weights of 120, 200, 400, 600, and 780 kg. The weights of carcasses, carcass quarters, beef cuts and their tissues (muscle, tendon, fat and bone) as well as meat quality traits were recorded. Results showed that carcass fat increased during growth primarily at the expense of bone and subsidiary muscle tissue, while the tendon content remained constant. Meat quality traits like IMF, meat color and tenderness were superior in high weight groups. Feeding high energy rations did not lead to increased fat accretion, but increased daily gain during certain stages of the fattening period.