L.C. Gonçalves

Níveis de proteína em suplementos para terminação de bovinos em pastejo durante o período de transição Seca/Águas: digestibilidade aparente e parâmetros do metabolismo ruminal e dos compostos nitrogenados

The objective of this trial was to evaluate ruminal, intestinal, and total tract apparent digestibilities of nutrients as well as metabolism of ruminal and nitrogenous compounds in supplemented finishing cattle during the drought to rainy transition season. Five Holstein x Zebu steers averaging 304 kg of live weight and 24 months of age located in five paddocks (0.34 ha each) of Brachiaria decumbens were used in this trial. The supplements fed (4 kg/animal/day) contained ground corn, whole soybean, urea, ammonium sulfate, and minerals and were formulated to yield, on as fed basis, 12, 16, 20, and 24% of crude protein (CP). Four animals were assigned to a 4 x 4 Latin square with experimental periods lasting 21 days. The remaining animal was not supplemented and was used for comparative purposes (CONT). No significant differences in ruminal, intestinal, and total tract apparent digestibilities of dry matter, organic matter, and neutral detergent fiber were observed by increasing the CP contents of the supplements. Similarly, abomasal flows of total nitrogen, ammonia nitrogen, and microbial nitrogen (MICN) did not differ when the CP contents of the supplements were increased. However, concentration of ruminal ammonia nitrogen increased linearly by incrementing the CP content of the supplement from 12 to 24%. Microbial efficiency averaged 17.5 g of MICN/kg of organic matter fermented in the rumen (OMFR) across supplements and was higher than that of the CONT (10.6 g of MICN/kg of OMFR). In addition, it was observed a significant cubic effect for urinary excretion of urea by increasing the CP contents of the supplements.

Concentrados protéicos para bovinos: 1. Digestibilidade in situ da matéria seca e da proteína bruta

This work aimed to determine the in situ rumen digestibility of dry matter (DM) and crude protein (CP) using 10 protein sources. Potential degradabilities of DM and CP of soybean meal, cottonseed meal, castorbean meal and palmist coconut meal were high (around 100%), however due to higher fractional degradation rates of soybean meal (10%) and lower for cottonseed meal (4%), castorbean meal (DM:3%, CP:1.2%) and palmist meal (1.7%), the effective degradability (ED) of soybean was significantly higher despite the rates of passage, showing this protein source has the highest ruminal nitrogen availability (from 86% to 63%, as rate of passage increased from 2 to 8%). Gluten meal is a low rumen degradable protein source (ED of CP: 16% for 0.05 passage rate). Among protein sources of animal origin, the highest potential CP degradability was observed for meat and bone meal (75.5%), followed by fish meal I (58.5%), feather and viscera meal (52.3%), and blood meal (36.7%). The highest ED for a passage rate of 5% was observed for meat and bone meal (51%), followed by fish meal I (41%), feather and viscera meal (40%) and blood meal (33%). Fish meal II showed very low rumen degradability with only 22% of CP disappearance at 48 hours of incubation.

Potencial forrageiro de cultivares de girassol produzidos na safrinha para ensilagem

The objective of this study was to evaluate some important agronomic traits for silage production of 12 hybrids and a variety of sunflower (Helianthus annuus L.) participant of the national assay of sunflower, in the agricultural year of 1996/97. The experiment was conducted from February to June 1997. The experimental procedure followed a randomized block design and the means values were compared by Student-Newman-Keuls test. Significant differences among hybrids for fresh and dry matter productions, leaf, head and stem percentages, stems circumference close the head, broken plants percentage and height of the plants were observed. No significant differences among hybrids for stems circumference close the ground, diameter of the head and laying plants percentage were found. The agronomic traits indicated that some hybrids of sunflower present potential to be used for silage production in double-cropping system, or during the drought.

Nutritional evaluation of “Braquiarão” grass in association with “Aroeira” trees in a silvopastoral system

This study aimed at evaluating the influence of a silvopastoral system (SPS) composed of “Aroeira” trees (Myracrodruon urundeuva) on the nutritional value of Brachiaria brizantha cv. Marandu forage grass over the rainy season. The experiment was conducted in the SPS located in the “Cerrado” biome in Lagoa Santa County, Minas Gerais state, Brazil, in the agricultural year of 2004–2005. It was evaluated the influence of “Aroeira”, whose density in the area was 140 trees/ha, on the following parameters of the B. brizantha cv. Marandu forage grass: forage mass harvest above stubble height, morphogenic attributes, bromatological composition and nutritional value. The effects of “Aroeira” trees on the micro-climatic conditions were also evaluated. The experiment adopted a randomized block design with five blocks (cutting seasons), two treatments (a shaded pasture—B. brizantha cv. Marandu shaded by M. urundeuva—and a pasture in full sun—B. brizantha cv. Marandu in full sun), and three replicates. The tree component, composed of the tree species M. urundeuva in the experimental density adopted, increased dry matter and crude protein of the forage mass harvest above stubble height, without affecting the concentration of neutral detergent fibre or acid detergent fibre, thus causing dry matter and organic matter in vitro degradability as well as effective degradability of the forage grass to remain the same as those obtained in full sun. Therefore, the results of this study show the possibility of using trees and grass to increase both animal production and environmental services.

Relação entre pressão e volume para implantação da técnica in vitro semi-automática de produção de gases na avaliação de forrageiras tropicais

O trabalho teve como objetivo demonstrar o procedimento inicial para a instalacao da tecnica in vitro semi-automatica de producao de gases em diferentes laboratorios, ou seja, estabelecer uma equacao que estime o volume (V) de gases produzidos no interior dos frascos por meio de dados de pressao (P) e V, obtidos manualmente durante a fermentacao de diferentes substratos. Foram utilizadas sete forrageiras: feno de Cynodon dactylon (tifton 85), Brachiaria brizantha (braquiarao), Neonotonia wightii (soja perene) e silagens de quatro genotipos de sorgo (Sorghum bicolor), que geraram 1036 dados de P e V. A equacao relacionando V e P obtida foi: V = -0,004 (s.e. 0,06) + 4,43P (s.e. 0,043) + 0,051 P2(s.e. 0,007), R2 = 0,99, a qual permitiu a instalacao da tecnica in vitro semi-automatica de producao de gases no laboratorio de nutricao animal do Departamento de Zootecnia da Escola de Veterinaria da UFMG.

Características de fermentação da silagem de cana-de-açúcar tratada com uréia, zeólita, inoculante bacteriano e inoculante bacteriano/enzimático

The characteristics of fermentation of sugarcane (RB72454) submitted to the treatments control; 0.5% urea; 0.5% zeolita; 0.5% urea and 0.5% zeolita; commercial bacterial inoculant and commercial bacterial/enzymatic inoculant were studied. The material stored in silos was opened on 1, 3, 5, 7, 14, 28 and 56 days of fermentation and was analysed for grades of MS, soluble carbohydrates, PB, NNH3/NT, pH, FDN, FDA, cellulosis, hemicellulosis, lignin and DIVMS. The reduction of the MS content of the silos was observed, with average of 21.1% compared to the original material (28.7%). The concentration of carbohydrates soluble on the original material was 19.7% and, after 56 days of fermentation, it was 0.92%. The concentration of PB in the control silage and treated with zeolita, commercial bacterial inoculant and commercial bacterial/enzymatic inoculant varied between 2.1% and 3.1% and in thoses that received urea and urea+zeolita was 8.4%. The grades of NNH3/NT were lower than 10% in the control silage and treated with zeolita, commercial bacterial inoculant and commercial bacterial/enzymatic inoculant. However, they were 30.4% and 31.1% in the silage with urea and urea+zeolita, respectively. On the first day of fermentation, the pH presented average of 3.75. After 56 days of fermentation, the concentration of FDN, FDA, cellulosis and hemicellulosis increased, presenting averages considering the treatments of 68.6%, 39.6%, 34.5% and 29.1%, respectively. The coefficient of DIVMS reduced with the fermentation, in all the evaluated treatments, being of 57.6% in the original material and averaging 47.6% in the silages.

Avaliação do feno de Arachis pintoi utilizando o ensaio de digestibilidade in vivo

Six sheep were used to evaluate intake and total apparent digestibilities of dry matter (DM), organic matter (OM), crude protein (CP), ether extract (EE), total carbohydrates (CHO), neutral detergent fiber (NDF), non fibrous carboidratos (NFC), acid detergent fiber (ADF), cellulose (CEL), hemicellulose (HCEL) and energy of Arachis pintoi hay. Nitrogen balance was also determined. Animals were kept in metabolic cages and received A. pintoi hay plus mineral salt. The Arachis pintoi was harvested with approximately 100 days. The supply of the hay was ad libitum with 20% allowed refusals. The experiment had 15 days of adaptation period and five days for sampling of hay, refusals, feces and urine samples. Chromium oxide was used as external marker to estimate fecal production. The intake of DM and OM of A. pintoi was 90.17 and 85.67 g/kg0.75, respectively. The crude protein, total digestible nutrients (TDN) and metabolizable energy (EM) were, respectively, 14.3%, 66.4% and 2.0 Mcal/kg DM. The nitrogen (N) balance was 12.1 g/day and represented 40.2% of total intake N. The total apparent digestibilities of DM, OM, CP, EE, CHO, NDF, NFC, ADF, CEL, HCEL and energy were 64.4, 68.4, 70.0, 63.4, 68.2, 53.6, 93.3, 47.2, 62.8, 66.8 and 63.7%, respectively. The Arachis pintoi hay showed high intake of digestible nutrients for a tropical legume forages, what gives support for its use in the feeding of ruminants.

Concentração plasmática de uréia e excreções de uréia e creatinina em novilhos

O trabalho foi conduzido com os objetivos de determinar a concentracao plasmatica de N-ureia (NUP), a excrecao fracional de ureia (EFU) e as excrecoes de ureia (EU) e creatinina (EC), para varias condicoes experimentais; estabelecer a relacao entre NUP, excrecao fracional de ureia e excrecao de ureia com a porcentagem de proteina bruta (PB) e fibra em detergente neutro (FDN) da dieta; e avaliar as perdas urinarias endogenas, por meio da determinacao da excrecao de creatinina. Nos experimentos I e II, foram utilizadas racoes constituidas de 25,0; 37,5; 50,0; 62,5; e 75,0% de concentrado formuladas para apresentarem niveis variados de proteina de acordo com a energia da dieta e niveis semelhantes de proteina (12% de PB), respectivamente. No experimento III, o nivel de concentrado foi fixo (40%), sendo variavel a idade de corte da graminea. No experimento IV, as racoes foram constituidas de 20,0; 32,5; 45,0; 57,5; e 70,0% de concentrado com, aproximadamente, 12% de PB. Utilizou-se o delineamento experimental em quadrado latino 5 x 5 para todos os experimentos, com excecao do III (4x4). Da urina total coletada em 24 horas, foram determinadas as excrecoes de ureia e creatinina. Para os experimentos I e III, a concentracao de NUP variou linearmente com a porcentagem de PB e FDN da dieta; a excrecao fracional de ureia e a excrecao de ureia tambem variaram da mesma forma para todos os experimentos. A excrecao de ureia aumentou linearmente com a concentracao de NUP. A excrecao de creatinina nao foi influenciada pelo teor de PB dietetico e foi proporcional ao peso corporal para todos os experimentos, com valor medio diario de 27,36 mg/kg PV, podendo ser usada para estimar as perdas endogenas de compostos nitrogenados.

Consumo e digestibilidade de novilhos Nelore sob pastagem suplementados com misturas múltiplas

The effect of three multiple mixtures supplementation on intake, digestibility and performance of Nelore steers grazing pasture of Brachiaria decumbens CV Marandu was studied. The multiple mixtures (treatments - T) were defined as: T1 - 800g of supplement with urea as crude protein source, T2 - 800g of mixture in which urea was replaced by starea, T3 - 1500g of starea, and T4 - mineral salt fed ad libitum as a control group. Six animals per treatment were given chromic oxide as a marker to measure intake and 10 animals per treatment were used to evaluate their performance. Two esophageal fistulated steers were used to collect samples of extruse. The animals fed on supplement diets showed higher weight gains (335, 419, 467g/animal) than those from the control group (271g/animal). Dry matter digestibility were 56.7, 49.8, 48.9 and 45.5%, respectively, for T1, T2, T3 and T4. A positive correlation between dry matter digestibility and in vitro dry matter digestibility (P<0.05) was observed. Supplementation with multiple mixtures increased dry matter intake (P<0.05).

Comparação de substratos com diferentes quantidades de carboidratos solúveis utilizando a técnica in vitro semi-automática de produção de gases

The difference between the gas production (GP) and the dry matter degradation (DMD) of substrates with different amounts of soluble carbohydrates using the in vitro gas production technique was studied. Five substrates (sugarcane, maize silage, Panicum maximum grass, corn grain, 20% CP commercial lactating cow ration and soybean meal) and the same substrates with part of its soluble carbohydrate removed (washed materials) were evaluated. The GP was higher and DMD was lower for washed materials than for the original materials. The carbohydrate concentration affects the results of the gas production technique.