Substituição de palma miúda por palma orelha de elefante mexicana para vacas em lactação

Abstract

The aim was to evaluate the replacement effects of using Nopalea cochenillifera Salm Dyck cv (“Miúda”) by Opuntia stricta (Haw) Haw (“Orelha de Elefante Mexicana” (OEM)) in diets for dairy cows on intake, nutrient digestibility, nitrogen balance, microbial protein, blood parameters, and milk performance, composition and fatty acid profile of lactating cows. Ten cows (569 kg od body weight (BW)) with an average milk yield of 20 kg/day were assigned to a double 5 × 5 Latin square. The experimental period lasted 105 days, with five consecutive periods of 21 days, that 14 were used to animal adaptation to diets and seven to data and samples collection. The experimental diets consisted of five replacement levels of “Miúda” by “OEM” (0, 25, 50, 75, and 100% on a dry matter (DM) basis) and were formulated considering the ingredients’ composition. The roughage: concentrate ratio was 70: 30 on a DM basis. The replacement of “Miúda” by OEM did not change intakes (kg/day) of DM (18.0), organic matter (OM = 16.3), crude protein (CP = 2.8), total digestible nutrients (TDN = 11.59), non fiber carbohydrates (NFC = 7.63), neutral detergent fiber (NDF = 5.7), apparent digestibility (g/kg) of DM (655), OM (694), CP (739), and NFC (950). On the other hand, apparent digestibility of total carbohydrates (Ŷ = 661 + 0.476x) and NDF (Ŷ = 273 + 1.108x) increased linearly. Microbial protein production (1,484 g/day), microbial protein efficiency (129.20 g CP/kg TDN), plasma ureic nitrogen (21.4 mg/dL), nitrogen balance (123 g/day), feed efficiency (1.12), nitrogen efficiency (0.23), milk production (19.98 kg/day), fat corrected milk production (20.12 kg/day), and milk composition were not influenced by the replacement. The most abundant fatty acids in milk fat are palmitic acid (C16:0) followed miristic acid (C14:0). The concentration of C16:0 tended to decrease (P<0.1) and C14:0 (11.811g 100-1 AG) did not change with the replacement of “Miúda” by “OEM”. The experimental diets did not influence the concentration of short-chain fatty acids (SCFA) as medium-chain fatty acids (MCFA). However, the branched chain FA (15:0 iso e 15:0 anteiso) decreased. C16:1 trans12, C18:0 iso, C18:1 trans-10, C18:1 trans-16 tended to increase (P<0.1) and C16:1 trans12, C18:0 iso, C18:1 trans-10, C18:1 trans16 tended to increase (P<0.10), and the concentration of C18:1 cis-11, C18:1 cis-13, C18:2 n-6 (linoleic acid - LNA), C18:3 n-6, C18:3 n-3, C23:0, the total concentration of C18:2, polyunsaturated fatty acid (PUFA), ω-6 and ω-3 increased (P<0.05) with addition of OEM. The concentration of others fatty acids did not change. We therefore recommend the use of OEM in the diets of lactating cows with an average milk yield of 20 kg/day.