Grazing lucerne as fattening management for young bulls: technical and economic performance and diet authentication

Abstract

Three fattening systems were evaluated from weaning to slaughter in order to find alternatives to grain feeding in young bulls, and to test the reliability of carcass subcutaneous fat colour to discriminate among them. After weaning (224 kg), one group of animals was fed concentrates and straw until they reached the target slaughter weight (450 kg; Feedlot), another group grazed rotationally on lucerne supplemented with 1.8 kg DM/day barley until slaughter (LUC), and the third group had the same management as LUC animals for 3 months (period 1) and thereafter was finished on concentrates and straw until slaughter (period 2; LUC + Feedlot). Animals were weighed weekly and sampled monthly for serum IGF-I and leptin, and plasma non-esterified fatty acids and carotenoid pigment concentration analyses. Carcass characteristics and subcutaneous fat colour were recorded after slaughter. In period 1, Feedlot animals had slightly greater weight gains than their grazing counterparts (P< 0.10), and at the end of period 1 they had 66% greater IGF-I and 35% greater leptin concentration (P< 0.01). Plasma carotenoid pigments were undetectable in Feedlot animals, but increased during grazing in LUC and LUC + Feedlot treatments. In period 2, weight gains were lowest for LUC, intermediate for Feedlot and greatest for LUC + Feedlot animals (P< 0.001), conditioning the time taken to reach slaughter weight (73, 58 and 47 days, respectively;P< 0.05). Leptin and IGF-I concentrations increased in all management systems during period 2. Plasma carotenoid pigment concentration reached its maximum at the end of period 2 in LUC animals, but it decreased sharply in LUC + Feedlot animals in this period. Management did not affect carcass traits except for subcutaneous fat colour. Yellowness, Chroma (C*) and the value of the integral of the translated reflectance spectrum (SUM), estimator of carotenoid pigment content in fat, were higher in LUC than in LUC + Feedlot and Feedlot animals (P< 0.001). Two logistic regressions were obtained to discriminate carcasses from LUC treatment: P (LUC) = (1 + e18.8–5.6 × lightness–36.9 × redness + 0.3 × SUM + 29.8 × C*)−1and LUC + Feedlot treatment: P (LUC + Feedlot)=(1 + e833.7–11.8 × lightness + 4.7 × redness + 0.2 × SUM−2.5 × C*)−1. The economic margin, calculated as income achieved minus costs, was greatest for LUC, intermediate for LUC + Feedlot and lowest for Feedlot treatment. Therefore, grazing lucerne supplemented with barley was an interesting alternative for fattening young bulls in these conditions, producing carcasses of similar quality, which could be accurately traced by measuring subcutaneous fat colour.

Economic Efficiency of Bull Fattening Operations in the Czech Republic

“…Most previous studies have concluded that feed costs represented the major component of total costs (e.g. Kvapilík, 2008;Blanco et al, 2011). In our study, feed costs accounted for 65 % of variable costs, which is somewhat lower than in the study by Norton (2005), who determined that feed costs may represent as much as 86 % of variable costs.…”

“…In contrast, total costs determined per fattened bull in Germany were as high as 28,944 CZK in 2011 (Gräfe and Eglinski, 2011) due to higher inputs, the technologies used, and different production conditions. Three fattening systems for young bulls from weaning at 224 kg to slaughter at 450 kg on average were evaluated in Spain (Blanco et al, 2011). Similarly to our study, total costs ranged from 19,440 to 22,491 CZK according to the feeding management used.…”

“…Sensitivity analysis of bull fattening operations had been carried out by Blanco et al (2011) and revealed that increasing input feed prices by 25 % resulted in 2-6 % higher total costs and 3-19 % lower profit.…”

Performance and Carcass Quality of Forage-Fed Steers as an Alternative to Concentrate-Based Beef Production

“…However, G-supp and TMR steers had costs associated to grazing and finishing, thus had 46 and 78% higher total feed costs than Control bulls, respectively. Nevertheless, young bulls finished on concentrates for 58 or 138 days had greater costs than young bulls that grazed for 164 days slaughtered with similar age and weight (Blanco et al, 2011). Finishing steers on the total mixed ration increased 18% total costs compared to G-supp steers because of the high dry matter intake during finishing and the price of the total mixed ration compared to grazing and the cost of producing the hay.…”

Effect of the winter diet on meat quality traits of steers finished on mountain pasture with a barley supplement

“…During this period different feeding strategies can be used bearing in mind that beef production systems need to be sustainable in economic terms. In order to achieve improved economic sustainability, the energy level of the diet during the winter housing period can be lowered to reduce feed costs (Blanco et al, 2011) and take advantage of the forage resources available during the grazing period. However, to date, few studies have been carried out on the effect of winter diets on steers in Mediterranean dry mountain areas.…”