Feed efficiency and maternal productivity of Bos indicus beef cows

Author(s)

Broleze, Danielly Fernanda ^[1] ; Souza, Luana Lelis ^[1] ; Zorzetto, Mariana Furtado ^[1] ; Savegnago, Rodrigo Pelicioni ^[1] ; Negrao, Joao Alberto ^[2] ; Bonilha, Sarah Figueiredo Martins ^[1] ; Mercadante, Maria Eugenia Zerlotti ^[1]

Affiliation

^[1] Ctr Avancado Pesquisa Bovinos Corte, Inst Zootecnia IZ, Sertaozinho, SP - Brazil

^[2] Univ Sao Paulo, Fac Zootecnia & Engn Alimentos, Pirassununga, SP - Brazil

• Document type: Journal article
• Source: PLoS One; v. 15, n. 6 JUN 3 2020.
• Web of Science Citations: 0

Abstract

This study evaluated 53 primiparous cows (36.8 +/- 1.23 months old and 484 +/- 40.9 kg of body weight) performance tested (GrowSafe (R) System) from 22 +/- 5 to 190 +/- 13 days of lactation in order to obtain daily dry matter intake (DMI). The animals received a high-forage diet (forage-to-concentrate ratio of 90:10). Milk production of the cows was evaluated three times by mechanical milking and the energy-corrected milk yield (ECMY) was calculated. Energy status (through the indicators glucose, cholesterol, triglycerides, and beta-hydroxybutyrate), protein status (indicators albumin, urea, and creatinine), mineral status (indicators calcium, phosphorus, and magnesium), and hormonal status (indicators insulin and cortisol) were estimated four times throughout lactation. The residual feed intake (RFI) of cows was calculated considering DMI, average daily gain (ADG) and mid-test metabolic weight (BW0.75) obtained in early lactation (from 22 +/- 5 to 102 +/- 7 days), and the animals were classified as negative (most efficient) or positive RFI (least efficient). The RFI model explained 53% of the variation in DMI. The mean DMI, ADG, ECMY, and calf weight as a percentage of cow weight were 12.47 +/- 2.70 kg DM/day, 0.632 +/- 0.323 kg/day, 10.47 +/- 3.23 kg/day, and 36.6 +/- 5.39%, respectively. Negative RFI cows consumed 11.5% less DM than positive RFI cows, with performance and metabolic profile being similar to those of positive RFI cows, except for a lower milk protein content and higher blood cholesterol concentration. In conclusion, negative (most efficient) and positive RFI (least efficient) Nellore cows, fed an ad libitum high-forage diet, produced similar amounts of milk, fat and lactose and had similar subcutaneous fat thickness, weight, calf weight as a percentage of cow weight, and blood metabolite concentrations (except for cholesterol). Therefore, there are economic benefits to utilizing RFI in a cow herd since cattle had decreased DMI with similar overall performance, making them more profitable due to lower input costs. (AU)

• FAPESP's process: 15/02066-4 - PHENOTYPIC EVALUATION OF FEED AND PRODUCTIVE EFFICIENCY, AND METABOLIC PROFILE OF NELLORE COWS
• Grantee: Maria Eugênia Zerlotti Mercadante
• Support Opportunities: Regular Research Grants