Leonardo Canali Canellas

Development and application of a bioeconomic efficiency index for beef cattle production in Rio Grande do Sul, Brazil

An index was developed to estimate the bioeconomic efficiency of production systems, identifying alternative scenarios that could improve their efficiency, and building isoefficiency relations in beef cattle production systems in Rio Grande do Sul. The concept of return on investment was used to develop the indicator. Scenarios regarded as efficient showed values higher than 3. The bioeconomic efficiency index for beef cattle production in the theoretical reference scenario was considered inefficient. At least four modifications in the variables method made it a bioeconomically efficient activity. These circumstances were studied using sensitivity analyses, with theoretical changes in the scenarios by changing variables two by two, while the others were kept constant. In Rio Grande do Sul, alternatives that make the activity efficient were identified by changing productivity, production cost, land price and product price. Isoefficiency relationships were identified in other scenarios. The application of this indicator in other agricultural activities, as well as the design of bioefficiency studies including both environmental and social welfare characteristics are recommended.

Competitividade inter-regional de sistemas de produção de bovinocultura de corte

This paper presents a methodology for evaluating production systems by measuring the intern competitiveness of in beef cattle. During the first quarter of 2010, questionnaires were administered to 65 farmers, 36 interviews in the Southern Region (State of Rio Grande do Sul) and 29 in the Northern Region (States of Para and Rondonia). Defined the key drivers that affect the international competitiveness - technology, management, market relations and institutional environment, an specific weight was assigned to each in order to get the index of competitiveness. The results were statistically analyzed by the item response theory and the correspondence analysis (ANACOR) with the SPSS® software. The South was more competitive than the North. Regardless of region, the critical factors of competitiveness were: crop-livestock integration, strategic planning, calculation of financial indicators, beef pricing, access to technological innovations and organization of farmers.

Post-weaning weight gain and pregnancy rate of beef heifers bred at 18 months of age: a meta-analysis approach

The objective of this study was to evaluate, using meta-analysis, the main factors related to post-weaning body weight and weight gain that affect pregnancy rate of heifers bred at 18 months of age. Data of 1398 beef heifers from six experiments were analyzed as a set. Information related to methodology and results of each experiment were codified in Microsoft Excel spreadsheets. The independent variables analyzed were: body weight at seven months of age (BW7M), daily weight gain from seven to 12 months (DWG7-12), body weight at 12 months of age (BW12M), daily weight gain from 12 to 15 months (DWG12-15), body weight at 15 months of age (BW15M), daily weight gain from 15 to 18 months (DWG15-18), daily weight gain from 7 to 18 months (DWG7-18) and body weight at 18 months of age (BW18M). The response variable was pregnancy rate (PR). Body weight at 18 months of age and DWG7-18 showed high correlation with PR and between each other. The other variables presented low correlation with PR. Body weight at first breeding and daily weight gain from seven to 18 months are the most important variables affecting the pregnancy rate of heifers bred at 18 months of age in the autumn. Weaning weight and weight gain during intermediate steps of the post-weaning period are not good predictors of pregnancy rate. Higher pregnancy rates can be obtained provided enough post-weaning weight gain and minimum body weight at first breeding are achieved, irrespective of when weight is gained.

Resposta reprodutiva de vacas de corte associada a marcadores moleculares relacionados à fertilidade

The association between the reproductive performance, expressed by pregnancy rate at fixed timed artificial insemination and birth rate in the subsequent season in beef cows, and molecular markers linked to genes for IGF-1 receptor, LHβ, leptin, and FSH and LH receptors were evaluated. Data from 249 Aberdeen Angus adult cows were used in this study. One hundred and ninety-nine cows were subjected to four different protocols for FTAI, followed by clean-up bulls and 50 cows formed the control group, matted only with bulls for 90 days during the mating season. Body condition score (BCS) and ovarian condition score (OCE) were evaluated at the beginning of the breeding season. The birth rate in the following year was 75.5%, with no treatments influence. The BCS has influenced the birth rate, respectively 55.6%, 75.8% and 82.4% (P<0.05) for animals with BCS less than 2.5; 2.5 to 2.9; and greater than or equal to 3.0, at the beginning of the breeding season. The markers related to IGF-1 receptor gene (AFZ-1 and HEL5) were associated with the birth rate in beef cows. Cows homozygous for AFZ-1 marker showed 84.4% of birth rate, while heterozygous cows showed 71.5% (P <0.05). The presence of allele *161 to the HEL5 marker was negative on birth rate. Cows with this allele had only 33.3% of birth rate, while cows without this allele had 76.5% of birth rate (P <0.05). These results demonstrate a significant association between the markers involved with the IGF-1 receptor and reproductive performance of Aberdeen Angus beef cows.

Desempenho e características da carcaça de novilhos terminados em pastejo rotacionado ou em confinamento

The productive performance and carcass of the 36 Brahman (Bh), Brangus (Bg) and adapted Hereford (He) steers finished on feedlot (FD) or on rotational grazing with supplementation system (GS) were evaluated. The animals were slaughtered when the subcutaneous fat thickness was over 4mm. The feedlot diet had a forage: concentrate of 60:40 (in dry matter) 13% crude protein (CP), 62% of NDT. The mombaca gras CP level was 7% and 54% of NDT. The supplement had supplied 24% of CP and 76% of NDT. A significant difference was observed for the average daily gain, being 1,200kg/head/day for FD steers and 0.675kg/head/day for GS steers. The effect of breed on slaughter weight was observed, being 445.8kg for Bh and Bg and 399.19kg for He. The hot dressing percentage was higher for Bh and Bg than for He, 58.4% vs 55.4%. The rib eye area was higher for Bg, 76.42cm2 and tenderness measured by the shear force was lower for FD steers, at 3.71 than for GS steers, at 4.89. The subcutaneous fat thickness was higher for FD steers, at 4.64 than for GS steers, at 3.39mm.

Relationships between age, weight, average weight gain and days on feed of beef steers slaughtered at 15 or 27 months of age

The main objective of this research was to evaluate the relationship between age, weight, average weight gain and days on feed of beef steers slaughtered at 15 or 27 months of age. Four hundred and thirty two beef steers were divided in two groups: 267 younger steers (YY), confined at 12 and slaughtered at 15 months old; and 165 young steers (YS), confined at 25 and slaughtered at 27 months of age. Beginning weight (BW) was 296.98 and 352.04 kg to YY and YS, respectively (p<0.01). Steers were on feedlot until reach a minimum fat percentage, resulting on seven different values for DF. In the statistical analysis the BW and the DF were calculated as co-variables. YS reach higher AWG (1.351 vs 1.004 kg/day) and higher SW (441.88 vs 388.88 kg) (p<0.01) and lower (p<0.01) DF (66.87 and 94.20 days, respectively). Steers with higher BW were sold earlier, reaching lower DF. Both groups showed a decrease tendency of AWG as the DF increased. YS reached higher AWG, resulting in lower DF compared with YY. In both groups, while the DF increases, the AWG decreases. Steers with higher BW reached lower DF