Metabolites and Hormones as Indicators of Postpartum Reproductive Efficiency of Supplemented Pasture- Based Friesian Dairy Cows at Kalro, Lanet, Nakuru County,Kenya
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Date
2025-10
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Kenyatta University
Abstract
High-yielding dairy cows experience a phase of substantial tissue catabolism in the
early postpartum period due to a negative nutritional balance that is partially brought
on by inadequate fodder quality and quantity. A significant obstacle to increasing cow
production is the requirement for feed ingredients during late pregnancy to sustain the
growth of the fetus and lactation following parturition. Metabolic signals and
regulatory hormones are linked to the mechanism for the restart of ovulation. The
ability of metabolites and hormone levels to predict nutritional condition and
postpartum reproductive efficiency in dairy cows in Kenya is unknown. Programs for
breeding and feed formulation may benefit from this data. The goal of the study was
to determine the role of hormones and feed metabolites as markers of postpartum
reproductive efficiency. Twenty cows were supplemented with total mixed ration feed
blocks (TMR) twice daily while grazing on Elba rhodes grass for eight hours/day.
Ten in-calf cows served as the control; they grazed on Elba rhodes grass for eight
hours without supplementation. Body condition scoring was done every fifteen days.
Gestation period, calf sex, milk production, and days to postpartum heat were
recorded. Analysis of feeds' chemical composition and digestibility were conducted.
Skimmed milk was prepared and kept at 4°C until time for laboratory analysis.
Jugular venipuncture was used to obtain blood samples into ethylene diamine
tetraacetate polystyrene tubes. The blood was spun at 1500 rpm for 15 minutes to
release plasma which was stored at -20°C until time for laboratory analysis.
Radioimmunoassay was used to track postpartum ovarian activity using skimmed
milk. Data was analyzed using statistical analysis system (2010). The results showed
that neutral detergent fibre of feeds used in this study ranged from 39.5±0.04 % to
41.7±6.7%. Nutrient components that highly positively correlated with metabolisable
energy were protein, methionine, and lysine. Supplementation significantly influenced
(p<0.05) metabolite and hormonal levels. Body condition score at calving was higher
among test cows (2.9±0.1) than the control (2.5±0.1). Test cows produced
significantly higher percentage (80%) of female calves than the control (20%). The
test cows took significantly shorter gestation period (278.4±1.0 days) than the control
(284.1±1.1 days). The test cows registered higher mean daily milk yield (9.1 L) than
the control (5.3 L). Test cows cycled earlier (50.4±0.90 days) than the control (62.7
±2.0 days). The test cows had significantly less number of insemination to conception
(1.35) than the control cows (2.7). Insulin like growth factor-1(IGF) and insulin
reduced with advanced pregnancy, with the test cows having significantly higher
values than the control. Glucose decreased with advanced pregnancy reaching
threshold day 15 postpartum with the test cows having higher values. Commencement
of luteal activity concided with low levels of non-esterified fatty acids (NEFA) and β hydroxybutyrate (BHB). Luteal activity progesterone was positively highly correlated
to IGF-1(p < 0.001, r2=0.672), and glucose (p < 0.001, r2=0.634) but highly
negatively correlated to NEFA (P=0.001, r2 = -0.689) and BHB (P=0.001, r2=0.679).
Glucose, NEFA, IGF-1, and BHB are good indicators of postpartum reproductive
efficiency. Data generated from this study is useful in reducing calving interval.
Supplementation of in calf cows with quality feed is recommended to reduce calving
intervals.
Description
A Thesis Submitted In Fulfillment Of the Requirements for the Award of the Degree of Doctor of Philosophy (Animal Physiology) in the School of Pure and Applied Sciences of Kenyatta University. October 2025
Supervisors
Michael Gicheru
Syprine Otieno