Milk yield estimation during suckling using the double oxytocin injection-milking and the double weighing-suckling methods in dairy goats

Abstract

The aim was to verify the validity of the double oxytocin-milking (DOT) method as milk yield estimator during the suckling period of lactating dairy goats. To this end, it was necessary to determine whether the weighing suckling weighing (WSW) and DOT methods of milk yield estimation satisfied the criteria to be considered valuable, the accuracy between both methods and the suitability of DOT to evaluate actual milk. At parturition, sixty lactating Murciano Granadina breed goats were separated into 2 groups, in mixed (MS; n = 24) and artificial rearing (ARS; n = 36) management systems. Until the sixth week of lactation (weaning), MS goats suckled one kid while kids from ARS goats were artificially reared; moreover, goats in both systems were submitted to once-a-day milking. Once per week, actual milk yield for ARS goats and potential milk yield were recorded using DOT method for all goats, except for 12 goats in ARS which remained as a control. Twelve goats from each management system were used to evaluate diurnal variation in milk production (DVM) by DOT method for 6 consecutive days in week 4 of lactation. No difference in DVM was found by DOT method in 4-h milk production of goats in MS (P = 0.099) or ARS (P = 0.220), which allowed sixfold multiplication of milked milk volume to obtain potential milk per day. ARS goats subjected to a weekly DOT and control group goats showed a similar (P = 0.379) lactation curve for the first 6 weeks of lactation. The DOT method slightly overestimated (3.4%, P = 0.005) the milk yield evaluated by WSW method for goats under an MS, but fitted the actual milk obtained by common milk records for the group of goats in an ARS submitted to the DVM test (P = 0.357) and the group in ARS alone (P = 0.163). The DOT method applied for 8 consecutive days led to a drop of 6 12% in milk yield during the following week for both production systems. In conclusion, DOT was an accurate method to estimate milk yield during the first weeks of lactation both in MS and ARS under the conditions of this experiment. © 2013 Elsevier B.V. All rights reserved.