Gabriel Cipriano Rocha

Produção de forragem e desempenho de novilhos de corte em um sistema silvipastoril: efeito de doses de nitrogênio e oferta de forragem

O estudo foi realizado com o objetivo de avaliar a producao forrageira e o desempenho de bovinos de corte pastejando sub-bosque de um sistema silvipastoril com eucalipto, adubado com fertilizante nitrogenado e duas ofertas de forragem. Os tratamentos consistiram de tres doses de fertilizante nitrogenado (0, 75 e 150 kg ha-1 de N, na forma de ureia), e duas ofertas de forragem (10 e 15% PV). O estudo foi conduzido sob delineamento inteiramente casualizado, com quatro repeticoes e tres periodos de avaliacao. Foi observado aumento no ganho de peso, apenas no primeiro periodo de avaliacao, a medida que se elevaram as doses de fertilizante nitrogenado. A variacao na oferta de forragem nao influenciou os ganhos medios individuais. O ganho por unidade de area aumentou a medida que foram adicionadas doses crescentes de fertilizante nitrogenado. A oferta de forragem de 15% e mais adequada quando se utilizam menores doses de nitrogenio na pastagem. Para doses mais elevadas, a intensificacao da utilizacao resulta em maiores ganhos por unidade de area. A fertilizacao do sub-bosque e eficiente e necessaria para a intensificacao do uso de sistemas integrados eucalipto-pastagem.

Evaluation of Laboratory Procedures to Quantify the Neutral Detergent Fiber Content in Forage, Concentrate, and Ruminant Feces.

A comparison was made of measurements of neutral detergent fiber concentrations obtained with AOAC Method 2002.04 and modified methods using pressurized environments or direct use of industrial heat-stable α-amylase in samples of forage (n=37), concentrate (n=30), and ruminant feces (n=39). The following method modifications were tested: AOAC Method 2002.04 with replacement of the reflux apparatus with an autoclave or Ankom(220®) extractor and F57 filter bags, and AOAC Method 2002.04 with replacement of the standardization procedures for α-amylase by a single addition of industrial α-amylase [250 μL of Termamyl 2X 240 Kilo Novo Units (KNU)-T/g] prior to heating the neutral detergent solution. For the feces and forage samples, the results obtained with the modified methods with an autoclave or modification of α-amylase use were similar to those obtained using AOAC Method 2002.04, but the use of the Ankom220 extractor resulted in overestimated values. For the concentrate samples, the modified methods using an autoclave or Ankom220 extractor resulted in positive systematic errors. However, the method using industrial α-amylase resulted in systematic error and slope bias despite that the obtained values were close to those obtained with AOAC Method 2002.04.

Evaluation of Acid Digestion Procedures to Estimate Mineral Contents in Materials from Animal Trials

Rigorously standardized laboratory protocols are essential for meaningful comparison of data from multiple sites. Considering that interactions of minerals with organic matrices may vary depending on the material nature, there could be peculiar demands for each material with respect to digestion procedure. Acid digestion procedures were evaluated using different nitric to perchloric acid ratios and one- or two-step digestion to estimate the concentration of calcium, phosphorus, magnesium, and zinc in samples of carcass, bone, excreta, concentrate, forage, and feces. Six procedures were evaluated: ratio of nitric to perchloric acid at 2:1, 3:1, and 4:1 v/v in a one- or two-step digestion. There were no direct or interaction effects (p>0.01) of nitric to perchloric acid ratio or number of digestion steps on magnesium and zinc contents. Calcium and phosphorus contents presented a significant (p<0.01) interaction between sample type and nitric to perchloric acid ratio. Digestion solution of 2:1 v/v provided greater (p<0.01) recovery of calcium and phosphorus from bone samples than 3:1 and 4:1 v/v ratio. Different acid ratios did not affect (p>0.01) calcium or phosphorus contents in carcass, excreta, concentrate, forage, and feces. Number of digestion steps did not affect mineral content (p>0.01). Estimated concentration of calcium, phosphorus, magnesium, and zinc in carcass, excreta, concentrated, forage, and feces samples can be performed using digestion solution of nitric to perchloric acid 4:1 v/v in a one-step digestion. However, samples of bones demand a stronger digestion solution to analyze the mineral contents, which is represented by an increased proportion of perchloric acid, being recommended a digestion solution of nitric to perchloric acid 2:1 v/v in a one-step digestion.

Avaliação técnico-econômica de suínos machos imuno e cirurgicamente castrados

This study was conducted to evaluate the technical and economic performance and determine profitability through the economic sensitivity analysis of immune (IM) and male pigs surgically castrated (SC). Two experiments were conducted in a completely randomized design, consisting of two treatments (IM and SC) with eight replicates of 10 animals each, totaling 160 pigs per experiment. It was found that IM pigs have lower feed intake and feed conversion during the growth phases in relation to SC. In the finishing phases, IM have better weight gain, feed conversion, carcass yield and lean meat percentage in relation to SC. The use of IM increases the profitability in pig production. The analysis of profitability differential between IM and SC should consider all stages of creation, since the differential performance of not castrated pigs during growth influences economic results of production.

Nutritional plans of digestible lysine for growing-finishing gilts

This experiment was conducted to evaluate nutritional plans of digestible lysine (DLys) for growing-finishing gilts. Eighty gilts with 63 days of age and an initial weight of 24.2±1.52 kg were distributed in a completely randomized block design, with five nutritional plans of DLys (9-8-7, 10-9-8, 11-10-9, 12-11-10, and 13-12-11 g/kg, from 63 to 103, 104 to 133, and 134 to 153 days of age, respectively) and eight replicates. Pigs were housed in pairs and fed their respective diets ad libitum throughout the experimental period (90 days). To monitor the animal development along the experiment at 103 and 133 days, gilts were weighed and subjected to analysis of ultrasound for evaluation of loin depth (longissimus dorsi) and backfat thickness. At the end of the experiment (153 days of age) the animals were weighed, and after slaughter carcasses were evaluated individually using a typifying pistol to evaluate the percentage and the content of carcass meat, loin depth and backfat thickness. From 63 to 133 days, there was no effect of the nutritional plans on daily feed intake, performance, or backfat thickness; however the loin depth was greater in the gilts that received plans with high levels of DLys (12-11; 13-12 g/kg) compared with the plan with the lowest level (8-7 g/kg). For the entire period (63 to 153 days), no influence of the nutritional plans was observed on the daily feed intake, performance variables, or carcass characteristics. A nutritional plan containing 9-8-7 g/kg of digestible lysine fed from 63 to 103, 104 to 133 and 134 to 153 days, respectively, meets the requirements for performance and carcass characteristics of growing-finishing gilts.

Collaborative study to evaluate the mineral content in feeds

Objetivou-se conduzir estudo colaborativo para avaliação do teor de matéria mineral em alimentos em sete laboratórios de análise de alimentos de instituições integrantes do Instituto Nacional de Ciência e Tecnologia de Ciência Animal (INCT-CA). Avaliaram-se seis alimentos: feno de capim-braquiária, cana-deaçúcar, silagem de milho grão, farelo de soja, milho e polpa cítrica. Solicitou-se a cada laboratório que as amostras fossem analisadas por seis dias, consecutivos ou não, sendo realizadas três repetições por amostra por dia de avaliação. Foi observado variação entre laboratórios, dias de análise e efeito de interação de material e laboratório. A variação dos resultados entre laboratórios correspondeu de 33,5 a 78,2% da variação aleatória total. Verificou-se que a repetibilidade representou de 8,5 a 51,6% da reprodutibilidade. Observou-se razões de Horwitz superiores a dois para três dos materiais avaliados. Foi constatado que 42,9% das avaliações apresentaram variações das estimativas em função do dia no qual a análise foi realizada. Também foram verificadas diferenças entre procedimentos de avaliação de matéria mineral em função dos diferentes laboratórios. Os teores de matéria mineral estimados pelos laboratórios participantes deste estudo apresentam baixa reprodutibilidade, o que é agravado pela presença de efeito de interação do material avaliado e do laboratório.

Evaluation of methods for the quantification of ether extract contents in forage and cattle feces

The objective of this study was to compare the estimates of ether extract (EE) contents obtained by the Randall method and by the high-temperature method of the American Oil Chemists Society (AOCS; Am 5-04) in forages (n = 20) and cattle feces (n = 15). The EE contents were quantified by using the Randall extraction or AOCS method and XT4 filter bags or cartridges made of qualitative filter paper (80 g/m²) as containers for the samples. It was also evaluated the loss of particles, and concentration of residual chlorophyll after extraction and the recovery of protein and minerals in the material subjected to extraction. Significant interaction was observed between extraction method and material for EE contents. The EE estimates using the AOCS method were higher, mainly in forages. No loss of particles was observed with different containers. The chlorophyll contents in the residues of cattle feces were not affected by the extraction method; however, residual chlorophyll was lower using the AOCS method in forages. There was complete recovery of the protein and ash after extraction. The results suggest that AOCS method produces higher estimates of EE contents in forages and cattle feces, possibly by providing greater extraction of non-fatty EE.

Lisina digestível para leitoas em fase de crescimento

Eighty gilts (24.2±1.52kg) with high genetic potential for lean gain were used in a randomized complete block design to evaluate five digestible lysine levels (9, 10, 11, 12 and 13g kg-1) during the growing phase (63 to 103 days of age). Gilts were housed in pair and fed their respective diets ad libitum. At the begging and the ending of the experimental period, gilts were weighed and scanned by ultrasound to measure loin area, as well as fat depth. The digestible lysine levels linearly increase (P 0.05) of the treatments on the fat depth and feed intake. The digestible lysine levels of 12 and 12.5g kg-1, corresponding to the intake of 23.6 e 24.6g dia-1, provide the best results of performance and loin area of growing gilts (63 to 103 days old).