Date of Graduation

2016

Document Type

Thesis

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Animal and Nutritional Sciences

Committee Chair

Robert A Dailey

Committee Co-Chair

Scott A Bowdridge

Committee Member

Ida Holaskova

Abstract

The aim of this study was to use leukocyte counts and haptoglobin concentrations in blood, milk, and uterine luminal secretion as biomarkers of health status and to associate those biomarkers and milk yield with reproductive success in dairy cattle. The study used a commercial dairy milking three times daily. One hundred and twenty six (25 primiparous and 101 multiparous) Holstein dairy cows were used. Reproductive success was evaluated with variables measured at three time points: [20-26 (prebreeding), 54-60 (breeding), and 90-96 (pregnancy diagnosis) days in milk (DIM)]. Variables included concentrations of leukocytes from blood, milk [measured by QScout Farm Lab MLD Slides (Advanced Animal Diagnostics, Morrisville, NC)], and uterine endometrium, culture of endometrial cells; Hp concentrations in plasma and milk; health status; and milk yield. Changes occurred in concentrations of biomarkers in blood, the uterus, and the mammary gland; however, concentrations showed no significant correlation between variables from the mammary gland and uterus (p > 0.05) or blood and the uterus (p > 0.05). Incidence of health disorders at 0 to 26 DIM was negatively related to conception to the first service (p = 0.0387). Reproductive diseases, including positive uterine culture for bacteria, negatively affected conception to first service (p = 0.0430). Both calving difficulty (p = 0.0223) and positive uterine culture (p = 0.055) negatively affected conception to first service; however, there was no interaction between the two. Plasma Hp concentration was affected by time (p < 0.0001), QScout Farm Lab udder diagnosis (p < 0.0001), and illness (p < 0.0001), and time by lactation interaction (p = 0.0384), with differences between primiparous and multiparous animals 20-26 DIM (p = 0.043). Illness status was associated with plasma Hp and milk yield (low41.96 kg) with higher plasma Hp concentrations having higher illness rates at 54-60 DIM (p < 0.0001) but not at 20-26 DIM (p = 0.0615). Mastitis negatively affected conception to first service with numbers of milk lymphocytes (p = 0.0357) and neutrophils (p = 0.0259) being elevated in mastitis positive animals. Milk neutrophils were positively correlated with milk Hp concentration (p < 0.0001). Logistic regression determined that illness status between 0-26 DIM was the most predictive variable (p = 0.0408) on conception to the first service with positive uterine culture (p = 0.0764) as the second most predictive. Plasma Hp concentration was not associated with illness status at 20-26 DIM but was a valuable marker of illness after the transition period, 54-60 DIM. The combination of calving difficulty, clinical signs of illness, uterine culture, and Hp plasma concentration (after 26 DIM) produced in the most predictive model of fertility. Hence, evidence of disease at the postpartum herd check was the most predictive of fertility in this herd of Holstein cows.

Download

Share

COinS