Cana-de-açúcar ensilada com diferentes graus Brix com ou sem óxido de cálcio e silagem de milho em dietas para bovino de corte

• Autor(a) principal: Magalhães, Felipe Antunes
• Data de Publicação: 2010
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5670
• topic: Bovinos de corte; Cana-de-açúcar; Desempenho; Silagem; Beef cattle; Sugar cane; Performance; Silage; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL

The sugar cane is a type of forage very used to feed ruminants, but its use in nature becomes difficult in larger production systems. Thus, the ensilage would be a way to contour this problem and these difficulties. However, the alcoholic fermentation that occurs in the sugar cane silage reduces its nutritional value. In this way, two studies were conducted: the first one evaluated the fermentation pattern of sugar cane silage with different Brix degrees, treated or not with 0.5% of calcium oxide; the second study consisted in four different treatments, which were used to compare the sugar cane silage with the corn silage. In the first study aimed to evaluate the effect of sugar cane ensilage with different Brix degrees (10.8, 12.0, 13.7, 14.5, 15.3, 16.3, 17.6, 18.7 and 20.9), with or without the addition of 0.5% calcium oxide on the chemical composition and fermentation losses of silage. The trial was conducted in a randomized design in factorial 9x2, making 18 treatments with three replicates. The material was ensiled in experimental silos every 15 days, and they were opened after 30 days of fermentation. As the Brix degree of the ensiled material was increased, there was an increase (P<0.05) of dry matter (DM) and decreased (P<0.05) of ash (CZ), crude protein (CP) and fibers (NDFcp and ADFcp). After fermentation, the DM content of the silage presented linear increase in comparison to the Brix concentration, and this increase was positively correlated with the lime amount; on the other hand, the CZ, CP, and NDFcp levels were reduced (P<0.05) with the Brix increase. Amongst the treated silages there were higher levels of CZ and EE, but the NDFcp and CP contents were lower in the silages with lime. The FDAcp content suffered linear reduction for treated silage, while in the untreated silage, there was a quadratic answer. The ethanol production, according to the Brix degree, presented a quadratically reply (P<0.05) for the silages without lime, and cubically (P<0.05) in silages with lime. The silages without lime as compared to those treated showed average levels of ethanol of 3.92 and 0.69% in the DM, respectively. The N-NH3 levels for silage with lime showed a linear increase (P<0.05) related to the Brix degree increasing, while in the control silage this effect did not occur (P>0.05). The treated or untreated silages presented an average pH of 3.98 and 3.50, respectively. The acetic and butyric acid levels were not affected (P>0.05) by the lime content and Brix degree. The untreated silages had a linear decreasing effect (P<0.05) for propionic acid levels as the Brix degree were increased. The higher the Brix degree value were, the higher the total losses of dry matter in treated or not treated sugar cane silage were (P<0.05). Silage without calcium oxide presented average losses of DM, gases and effluent by 18.3%, 12.9% in the DM and 137.7 kg/t of FF, and for the treated silages these losses were 11.3%, 5.3% in the DM and 106.0 kg/t of FF, respectively. In the second study were done three experiments. In experiment 1, which aimed to evaluate the effect of diets containing sugar cane silage with low (SCBB) and high Brix degree (SCAB), with (T) or without addition of 0.5% of calcium oxide, and corn silage (CS), with concentrate offered on the base of 1% of body weight (BW) on the intake, performance and commercial cuts income of feedlot beef cattle. In this experiment were used 35 steers, European-Zebu crossbred, with an average initial body weight (BW) of 350 ± 32.96 kg, five of whom were slaughtered at the beginning of the experiment (reference group), and the other 30 were distributed in randomized blocks, with five treatments and six blocks (replicates), considering the body weight as a criterion for blocks. In experiment 2 were used five steers, European-Zebu crossbred with an average initial body weight (BW) of 350 ± 18.99 kg, distributed in a 5x5 design incomplete Latin square, with the same five treatments of the first experiment, five animals, and four periods, with the objective to determine the digestibility of the constituents of the diets and the microbial protein production. Each experimental period had 21 days, eighteen of which to adaptation to the diets and three for data collection. At the end of experiment 1, all of the animals were slaughtered and their gastrointestinal tracts were emptied to determine the empty body weight (EBW). Apart from the neutral detergent fiber (NDFcp) intake in % BW, the diet containing corn silage (CS) showed better (P<0.05) intake of other nutrients from the diet and better weight gain (WG). For the carcass features, only the carcass income in relation to the BW and EBW was not affected (P>0.05) by the diets, and the other carcass features were higher (P<0.05) for the diets containing CS. It did not occur any difference (P>0.05) between the diets containing sugar cane silage (SC) for the carcass features. The DM intake and the ADG of animals fed with the diets containing CS and SC were 9.82 and 1.48 and of 7.65 and 0.93 kg/day, respectively. The animals that received the diet containing sugar cane silage with high Brix (SCAB) had (P<0.05) lower intake of indigestible neutral detergent fiber (iNDF) and NDFcp (% BW), than those that received the diet containing SCBB. The animals that received the diet containing sugar cane silage treated with high Brix (SCTAB) had less intake (P<0.05) of NDFcp and iNDF (% BW), than those that received the one containing SCAB. There was lower (P<0.05) access number and greater time of stay for access to the trough, for the diet containing CS. The diet containing CS had higher digestibility (P<0.05) for all the nutrients, except for the crude protein (CP) and the non-fiber carbohydrates (NFC) which did not differ in comparison to the diets containing sugar cane silage. Among the diets containing sugar cane silage, there were no (P> 0.05) difference in the digestibilities, with the exception for the diet containing SCTAB which had the higher NDFcp digestibility (P<0.05) compared with the diet containing SCAB. There were not any effect (P>0.05) of the diets containing SC on the excretion of nitrogenous compounds in urine. However, the diet containing CS showed lower excretion (P<0.05) of these compounds. There was higher (P<0.05) synthesis of microbial crude protein in the diet containing CS in comparison to the diets containing SC. There were no differences (P>0.05) among the treatments for microbial efficiency. In experiment 3 the aim was to evaluate the effect of diets containing sugar cane silage with low and high Brix degree, with or without 0.5% of calcium oxide and corn silage on the totals and partials digestibilities, the ruminal parameters (pH, ammoniacal N, rates of digestion and passage) and the balance of nitrogenous compounds. There were used five steers, European-Zebu crossbred, ruminally and abomasally cannulated with average BW of 180 ± 31.81 kg, distributed in a 5x5 Latin Square, with the five treatments (arranged in a 2x2 factorial+1) consisting of diets containing sugar cane silage with two levels of calcium oxide (0 or 0.5% on the basis of natural materia) and two Brix degrees (15 and 20o) and corn silage, with the concentrate being offered on the basis of 1% of the BW. There were done five experimental periods of 14 days each, with seven days for diets adaptation and seven days for data collections. The animals submitted to the diet containing corn silage (CS) had higher (P<0.05) intake of dry matter and nutrients in comparison to those animals that received the diets containing sugar cane silages. There were no differences (P>0.05) for the intakes between the diets containing sugar cane silage, except for the NDFcp intake (% BW), in which case the animals submitted to a diet containing treated sugar cane silage with low Brix (SCTBB) showed a lower intake (P<0.05) compared to those whose diet contained sugar cane silage with low Brix (SCBB). Apart from the total apparent digestibility of NFC, there was greater total apparent digestibility (P<0.05) for the DM and other nutrients for cattle fed with diet containing CS as compared with those receiving diets containing sugar cane silage. There was no difference in the total apparent digestibility (P>0.05) of the DM and nutrients between the diets containing sugar cane silage, except for the NDFcp digestibility that was lower for the diets containing SCAB in comparison to the diets containing SCBB. There was no difference (P>0.05) for the ruminal and intestinal digestibilities of the nutrients between the diets containing sugar cane silage. The diet containing CS had higher (P<0.05) ruminal digestibility of the DM and intestinal for the EE. It was possible to be observed that the ingestion rates (ki) and digestion (kd) (P<0.05) were higher for the DM and NDFcp for the diet containing CS in comparison to the diets containing sugar cane silages. The ingestion rates of iNDFcp did not differ (P>0.05) between the diet containing CS and those containing sugar cane silages. There was no difference (P>0.05) for the rates (ki, kp and kd) of DM and NDFcp between the diets containing SC. The ki rates of the iNDFcp were lowers (P<0.05) for the diet containing SCTAB when compared to the diet containing SCAB. There was no difference (P>0.05) among the treatments for urea nitrogen concentrations in serum, except for the diet containing CS which showed the lowest value in comparison to the diets containing SC. There was no difference (P>0.05) for the microbial nitrogen compounds synthesis and rumen microbial crude protein synthesis in the diets studied. The animals that received CS presented lower (P<0.05) microbial synthesis efficiency than those with the diets containing SC. It is possible to be concluded that the treatment of the sugar cane with 0.5% calcium oxide at the natural material base was effective to reduce the unwanted fermentation resulting in a greater conservation of the ensilage material. The diet containing CS provided higher intake, digestibility of the most of nutrients and performance in comparison to the diets containing SC. The lime utilization during the sugar cane ensilage or the use of sugar cane with 15 or 20 Brix degrees did not alter the intake, the digestibility and the performance of beef cattle, so it suggests that the sugar cane can be ensiled with Brix degrees varying from 15 to 20.