The influence of flushing diet composition on the reproductive performance of Dohne Merino (Ovis aries) ewes

Date
2020-12
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Abstract
ENGLISH ABSTRACT: The study investigated the influence of different flushing diets on the live weight, back-fat thickness, and follicle development in semi-intensively managed Dohne-Merino ewes. The different flushing diet treatments consisted of a flushing diet consisting of sweet lupins (L) only, a commercially available industry-standard flushing (SFD) diet, and a commercially available super-fertility flushing diet (SUFD). A total of 48 sexually mature Dohne Merino ewes were allocated to four treatment groups, including to the control group that received no flushing diet. The flushing diets were fed at 250g/day/ewe for 6 weeks, i.e. three weeks prior to the introduction of the intact ram until three weeks after the rams was introduced. Parameters recorded include live weight, back-fat thickness (BT), number of follicles observed on ovaries, and mean follicle size. Treatment diet significantly influenced the ADG of the ewes and accumulated in a dynamic effect of flushing, where SFD-fed ewes gained 0.125g/day (SE ± 0.018), followed by SUFD-fed ewes (0.122g/day, SE ± 0.023), L-fed ewes (0.098g/day, SE ± 0.024), and the control group ewes (0.015g/day, SE ± 0.026). The change in BT measured at the end and beginning of the trial, respectively, was significantly influenced by ewe age, with the biggest difference in BT for ewes aged three years (0.316mm, SE ± 0.025), followed by ewes aged four years (0.198mm, SE ± 0.030), ewes aged six years (0.063mm, SE ± 0.030), ewes aged two years (0.034, SE ± 0.017), and the ewes aged five years that lost backfat (-0.011mm, SE ± 0.038). Ewe age significantly contributed to the variation in follicle size, with average follicle size the largest for ewes aged two (SE ± 0.079)- and three years respectively (4.412mm, SE ± 0.101), followed by ewes aged six years (4.408mm, SE ± 0.092), ewes aged four years (4.271mm, SE ± 0.085), and the ewes aged five years had the smallest average follicle size (4.097mm, SE ± 0.094). The interaction between treatment and age was significant for SUFD-fed ewes 5 years of age, and SFD-fed ewes 6 years of age. No correlation was observed between ewe live weight and mean follicle size.
Description
Thesis (MScAgric)--Stellenbosch University, 2020.
Keywords
Diet, Dohne Merino, Sheep -- Breeding -- Cost effectiveness, Merino sheep -- Breeding -- South Africa, Sheep breeds -- Genetics aspects -- South Africa, Sheep farming -- South Africa, Ewes, UCTD
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