SERUM HORMONE LEVELS AND MILK YIELD AMONG FRIESIAN CATTLE AT DIFFERENT PARITIES – THIRTY DAYS POST - PARTURIENT

Abstract

The study examined the interactions between feeds, parity, milk-yield and hormonal profile of Friesian cows during the 30- day into lactation. The study objective included: to investigate the impact of parity on weight change and milk yield of post - parturient Friesian Cows; to examine the effect of serum hormone levels on feed intake of post – parturient Friesian Cows; and to determine the effect of parity on serum hormone levels of post – parturient Friesian Cows in Uasin Gishu County, Kenya. Three farms namely Elfam, Elso and Betan in Uasin Gishu County were purposively selected with nine pedigree Friesian cows in three parities (2, 3 & 4) whose milk production averaged 20 litres/day. The study utilized a randomized complete block design and adopted a natural on–field experiment while adopting their nutritional diets. Each cow was fed daily on 40 kg of forage, mineral licks and water ad libitum. The daily milk yield was recorded. Feed intake was determined daily and blood samples collected at parturition and on 7- day interval and tested for cortisol, prolactin, oestrogen, and IGF-α1 levels. Resulting data were entered into Microsoft Excel application and analysed using Genstat 14 to generate descriptive statistics and ANOVA, and results presented in tabular and graphical formats. All the lactating cows irrespective of parity progressively lost weight daily with cows in parity 2 having the highest average daily weight loss. Milk yield significantly differed with cows in parity 2 having the lowest daily milk yield at 21.66 Kgs/day while cows in parity 4 had the highest daily milk yield at 24.99 Kgs/day. All the cows had on average low feed intake at parturition and progressively increased the feed intake to 35 Kgs/day. Serum cortisol levels gradually declined while serum IGFα1, prolactin and oestrogen levels progressively rose. Parity had a significant effect on weight change (p < 0.05) and milk yield (F = 8.27, p < 0.05). Serum hormone levels; prolactin (r = 0.760, p < 0.05), Oestrogen (r = 0.785, p < 0.05) and IGF-α1 (r = 0.692, p < 0.05) significantly and positively correlated with feed intake which negatively correlated with serum cortisol (r = -0.613, p < 0.05). Only serum cortisol levels differed significantly with parity levels. The study concluded that a correlational and causal linkages exist between parity, serum hormonal profile, feed intake and milk yield of post-parturient Friesian cows in Uasin Gishu County. The study recommends that farmers improve herd management techniques for managing and sustaining the cow’s physiological state (weight loss and milk yield) during the immediate post – parturient period. Further, there is need for the farmers to intensify the feed intake through improve feed palatability to support and maintain the growth profiles of the dairy cows and that farmers improve the nutritional diets by proper feed formulation to accommodate the changing physiological needs of the post – parturient lactating cow.