Substituição parcial do farelo de soja por uréia e palma forrageira (Opuntia fícus indica Mill) em dietas para vacas em lactação: I. Desempenho

Abstract

RESUMO -O objetivo desse trabalho foi avaliar a substituição parcial do farelo de soja por nitrogênio não protéico no desempenho de vacas holandesas em lactação. Oito animais com 90 dias de lactação e 600 kg de peso vivo, no início do experimento, foram distribuídos em dois quadrados latinos (4X4). A uréia representou 0,0; 0,8; 1,54; e 2,40% da matéria seca (MS) da dieta, correspondente a 2,32; 4,65; 6,66; e 8,02% de proteína bruta (PB) na forma de compostos nitrogenados-não-protéicos (NNP), que representaram os tratamentos experimentais. O consumo de PB apresentou comportamento quadrático, com valor máximo de 3,3 kg/dia para o nível de 4,71% de NNP. O consumo de cálcio (Ca) aumentou e o de matéria seca (MS); matéria orgânica (MO); extrato etéreo (EE); carboidratos totais (CHT); carboidratos-não-fibrosos (CNF); fibra em detergente ácido (FDA) e nutrientes digestíveis totais (NDT) diminuíram linearmente, enquanto os consumos de fibra em detergente neutro (FDN) e de fósforo (P) não foram influenciados pelos tratamentos experimentais. As produções de leite sem e com correção para 3,5% de gordura diminuíram linearmente com a inclusão de uréia e palma forrageira nas dietas. A produção de gordura, proteína, a composição do leite, e a eficiência alimentar (kg de leite/ kg de MS consumida) não foram afetadas pelos níveis de NNP.Palavras-chave: consumo, composição e produção do leite, NNP, proteína Partial Replacement of Soybean Meal for Urea and Forage Cactus in Lactating CowsDiets. I. Performance ABSTRACT -The work was carried out to evaluate the partial replacement of soybean meal by urea and forage cactus on the performance of lactating dairy Holstein. Eight cows with 90 days in milk and 600 kg of initial average LW, were assigned in a two 4 X4 latin square design. The urea represented 0.0, 0.8, 1.54 and 2.40% of dry matter (DM) of the diets, correspondent to 2.32, 4.65, 6.66 and 8.02% of crude protein (CP) levels in the form of non protein nitrogen compounds (NPN), that represented the experimental treatments. There was a quadratics effect of levels of NPN on the intake of CP, with maximum intake of 3.3 kg/day with 4.71 % of NPN. The calcium (Ca) intake increased, and dray matter (DM); organic matter (OM), ether extract (EE), total carbohydrates (TCH), non fibercarbohydrates (NFC), acid detergent fiber (ADF) and total digestible nutrients (TDN) intakes decreased linearly. The intakes of neutral detergent fiber (NDF) and Phosphorus (P) was not affected by NPN levels. The milk production and fat corrected milk (3,5%) decresed linearly as levels of urea and forage cactus increased. The yield of fat, protein, milk composition and feed:eficiency ration was not affected by NPN levels. IntroduçãoA exploração pecuária da região Nordeste é afetada pelas constantes secas e irregularidade das chuvas, impedindo uma exploração racional da atividade leiteira, uma vez que exige uma constância na produção e oferta de alimentos, deste modo, inviabilizando os sistemas tradicionais de produção, restando aos produtores a utilização de...

Urea in sugarcane-based diets for dairy cows

“…The PUN value in this study was, however, smaller than values observed in studies in which intake reduced as UAs were increased (from 19.90 to 23.08 mg/dL) (Silva et al 2001a,b;Oliveira et al, 2001;Oliveira et al, 2004). The lower PUN value observed in the present study in relation to those of Silva et al (2001a,b), Melo et al (2003) and Oliveira et al (2004) is possibly related to the nature of the dietary carbohydrates present in the sugarcane, which are mostly soluble in neutral detergent, especially those rich in sugars, of higher rumen degradation rate in relation to the amylaceous fractions, and the ones insoluble in neutral detergent, which are typical in silages of corn and sorghum (Lanzas et al, 2007). A higher rumen degradation rate of the fraction of sugars propitiates greater synchrony with the rate of rumen ammonia availability through urea, allowing for lower accumulation of rumen ammonia (Nocek & Russell, 1988).…”

“…This result is consistent with Rangel et al (2008), who, utilizing the same levels of urea in the sugarcane, but with a lower roughage:concentrate ratio in relation to the present study, also did not observe effect on the performance of dairy cows with production above 20 kg/day. However, it is not in line with other researchers, who observed linear decrease in the milk yield of cows fed increasing levels of urea (up to 21 to 24 g/kg DM of the diet), but utilizing corn or sorghum silage or a mixture of corn silage and forage cactus as exclusive source of forage (Silva et al, 2001a;Melo et al, 2003;Oliveira et al, 2004).…”

“…This result is consistent with Rangel et al (2008), who did not observe effect of the source of nitrogen (soybean meal vs. urea) and of the level of UAs in the sugarcane (4, 8 and 12 g/kg of sugarcane, as fed) on the intake of dairy cows with milk production above 20 kg/day. However, it contradicts other researchers who observed linear decrease in the DMI of dairy cows with increase in urea up to the level between 21 and 24 g/kg DM of the diet, but utilizing corn or sorghum silages or a mixture of corn silage and forage cactus (Silva et al, 2001a,b;Melo et al, 2003;Oliveira et al, 2004). In spite of the elevated level of urea in the diet (up to 30 g/kg DM), the absence of effect on intake is probably related to the pool of ammonia in the blood circulation, which probably remained at thresholds lower than the necessary to cause malfunctioning of the body tissues by energy deficit, especially the brain tissue, with consequent reduction of intake (Detmann et al, 2007).…”

“…For the analysis of the neutral detergent fiber (NDF), samples were treated with thermostable alpha-amylase without the use of sodium sulfite, corrected for the ash residue (Mertens, 2002) and for the residue of nitrogen compounds (Licitra et al, 1996). Analyses of NDF and ADF were performed in an Ankom ® system using TNT (non-woven textile) bags with dimensions 5 × 5 cm, keeping average ratios of 14 mg DM/cm 2 fabric and neutral detergent at 100 mL/g of airdried sample.…”

“…However, the addition of up to 20 g urea/kg DM in the diet to diets based on corn or sorghum silage has been show to decrease intake and performance of dairy cows (Melo et al, 2003;Oliveira et al, 2004).…”