Abstract:
The dairy characteristics of small-holder agropastoral goats were evaluated using records obtained from a total of 250 does at Jigawa and Katsina States over a period of one year. The data collected included milk yield, udder characteristics, body conformation traits, blood metabolites profile, haemoglobin and potassium gene and genotypic frequencies. The potential of using these polymorphic genes and coat colour variations as markers for milk yield was also determined. The effects of location, parity and breed on milk yield, udder and conformation traits were also evaluated. The data obtained in this work were analysed using General Linear Model of SAS. The results show that total milk offtake was 29.35kg, average daily yield 248.22g, initial yield 243.57g, peak day 33.04 days, peak yield 358.72g, lactation length 118.26days and last test day yield 100.68g. The milk yield characteristics, udder and body conformation traits were significantly (P< 0.05) influenced by age, parity, coat colour and breed. The correlations amongst milk yield characteristics were significantly positive (P<0.01-0.05; r=0.005-0.926). The average udder characteristics were; udder Height (UH) 12.39cm, udder circumference (UC) 31.86cm, distance between teat (DT) 8.76cm, teat length (TL) 3.52 and teat circumference (TC) 5.00cm. The correlations between udder and milk yield characteristics were positive and ranged from moderate to high ((P<0.01-0.05; r =0.07-0.52). The means of the conformation traits were: body weight (BWT), 28.83kg; stature (ST), 65.43cm; Body depth (BD), 79.04cm; Height at withers (HW), 60.82cm; Heart girth (HG), 69.83cm; and Body length (BL), 60.68cm. The correlation between body conformation traits with milk yield characteristics were low to moderate (P<0.01-0.05; r = 0.01-0.39). Two haemoglobin variants HbA and HbB with three genotypes were identified, HbAA, HbAB and HbBB, Gene frequencies were 0.683 and 0.316 for HbA and HbB, respectively while their genotypic frequencies were 0.467, 0.431 and 0.099 for 9 HbAA, HbAB and HbBB, respectively. Two potassium types were identified HK and LK, their gene frequencies were 0.844 and 0.156; their genotypic frequencies were 0.91 and 0.01 for HK and LK, respectively. Milk production traits varied significantly (P< 0.05) with Hb-types. HbAA and HbAB were superior on ADY and PY to HbBB. Potassium types had no significant (P>0.05) influence on milk yield characteristics. Hb-types significantly (P<0.05) influenced packed cell volume (PCV) and Haemoglobin concentration (HB) in the blood while K-types significantly (p<0.05) influenced Na concentration. The mean values of blood biochemical profiles were 28.47% PCV, 9.49g/dl HB, 136.40mmol/l Na, 64.44g/L Total protein, 31.12 g/L Albumin, 33.12 g/L globulin and 4.44 g/L glucose. Animals with combination of haemoglobin AA, and high potassium (HK) with brown/white coat colour (AAHKBW) were superior in most of the milk production characteristics, while those with combination of HbAA, HK and white coat colours (AAHKW) were superior to other combinations in body conformation traits. It was concluded that the high preponderance of allele HbA and HK in the study area suggests that these alleles are favored by natural selection in North West zone of Nigeria and should be explored as indirect selection criteria for milk yield characteristics in goats.
RELATIONSHIP OF HAEMOGLOBIN AND POTASSIUM POLYMORPHISM WITH CONFORMATION, MILK PRODUCTION AND BLOOD BIOCHEMICAL PROFILES IN AGROPASTORAL GOAT
