Health management, reproductive hormones and productive performance of dairy cattle in hot-humid and coastal environments, Ghana

Abstract

The objectives of this study were to (1) assess prevalence of tick and tick-borne diseases (TBDs) and factors influencing their management in dairy cattle herds in hot-humid and coastal environments of Ghana, (2) find out effect of breed physiological state and feed supplementation on haemato-biochemical indices of cows, (3) assay gonadotrophic and reproductive steroid hormones using commercial enzyme immunoassay (EIA) and (4) assess factors influencing productive performance and milk quality of dairy cows in the study areas. The study was conducted in Ashanti, Eastern and Greater Accra Regions of Ghana from July, 2015 to August, 2018. Twenty eight (28) farms were purposively chosen, from which a total of 1052 dairy cattle breeds were used for the study. Tick identifications were done as described in literature whereas determination of prevalence of TBDs were done through culturing, microscopy and molecular (PCR) confirmation. Haematology of dairy cows was determined using fully automated BC 5800 haematology system. Serum biochemical indices were assessed using Mindray BS 130 fully automated blood chemistry analyser. Blood glucose level was determined using portable glucometer. Reproductive hormones were assayed using commercial EIA (ELISA). Data on milk yield were measured with 1 litre graduated beaker after hand milking. Milk composition analysis was carried out as decribed in literature. Lactometer, pH meter, haemocytometer and standard plate count were used for milk quality assessment. Data were analysed using IBM SPSS version 25 for windows. Analysis of data showed that, the most prevalent tick species was Amblyomma variegatum, followed by Boophilus decoloratus, Rhipicephalus spp. and Hyalomma rufipes in descending order. Effect of breed, farm and location on Log10 (X +1) + 0.5 total tick loads/infestations were masked by management regimes and level of biosecurity practices observed by farmers. Jersey cattle had the least (P<0.01) tick load. Dairy herds kept under exclusive zero grazing had the least (P<0.01) tick infestation, followed by partial zero gazing and range grazing in descending order. Dermatophilosis was the most prevalent (27.37 %) tick-borne disease (TBD), followed by anaplasmosis (21.40%) and heartwater/cowdriosis (7.41%). PCR assay showed a prevalent rate of 92.50 %, 33.75 % and 10.00% for Dermatophilus congolensis, Anaplasma marginale and Ehrlichia ruminantium, respectively. Dairy cattle herds reared under exclusive zero grazing, insect proof barns and moderate level of biosecurity practices had no prevalence of the TBDs whereas cattle kept on range grazing had the worst. In post tick infestation, University of Education, Winneba http://ir.uew.edu.gh

weekly application of acaricide resulted in the lowest (P<0.01) tick infestations and incidence of TBDs. Red blood cells, HGB and HCT were highest (P<0.01) in Sanga while Friesian-Sanga crossbreds and Jersey cows had similar (P>0.05) values. Values of MCV and MCH were highest (P<0.01) in Jersey, followed by the crossbreds and Sanga in descending order. Breed had little (P>0.05) effect on mean values of MCHC, RDW, PLT, MPV, PDW and PCT. Breed also influenced (P<0.01) serum concentration of hepatic enzyme ALP but had insignificant effect on ALT, AST and γGT. Sanga had the highest (P<0.01) concentrations of serum mean total protein (TP) and globulin. Direct bilirubin, urea/BUN, cholesterol, HDL, ketone, and chlorine, potassium, and phosphorus ions/cations concentrations were dependent on the type of breed. Nevertheless, breed was not a good determinant of serum levels of Na+, Ca2+, HCO3-, and Mg3+. Physiological state influenced erythrocytes indices such that values were generally high during gestation. Haematocrit (HCT) was higher (P<0.01) in heifers and dry cycling cows than those observed in gestation periods. Higher (P<0.01) level of WBC, neutrophils, lymphocytes, eosinophils and basophils were noticed in first trimester of gestation (GE). Physiological state had high (P<0.01) effect on serum ALT, AST, GGT GGT, triglycerol, cholesterol, and NEFA levels. Slight (P>0.05) elevation in serum ALP was observed in non-cycling heifer. Heifers and Cycling cows (CC) had higher (P<0.01) protein profile than cows in gestations. Physiological states had little (P>0.05) effect on most serum electrolytes but influenced (P<0.05) HCO3- and potassium. Cows in GL had the lowest (P<0.01) serum phosphorus (P) concentration. Haemato-biological indices generally improved with regular feed supplementation. Progesterone (P4) concentrations during pre-pubertal stages ranged from 0.21 to 0.96 ng/mL. Physiological onset of impending cyclicity marked by a P4 rise of ≥ 1.0 ng/mL occurred at the 415th, 295th and 285th day in Sanga, crossbred, and Jersey heifers respectively. The first overt heat in Sanga, crossbred, and Jersey heifers occurred in 435th, 340th and 320th day respectively. Feed supplementation led to early onset of cyclical activity, and conception with increased (P<0.01) in P4 levels with increasing level of feed supplementation. There were significant positive correlations of 0.92, 0.90, 0.71, and 0.93 between serum and milk concentrations of oestradiol, progesterone, testosterone, and FSH, respectively, during 45 days postpartum. Serum and raw milk concentrations of LH were moderately and negatively correlated (- 0.38). Testosterone concentration increased with increasing age of bulls from one year and peaked at age four. The highest (P<0.01) level of oestradiol was observed in 1 year old bulls, whereas bulls of up to 6 months, and 2, 3, 4 and 12 years old had similar (P>0.01) oestradiol concentrations. Insect proof farm housing, regular feed supplementation, good body condition score 3 to 4, cows of parity 2 to 5, wellset big udder with medium teat size and milking twice a day had high (P<0.01) milk yield with normal composition at lengthier (P<0.01) lactation length. Quality assessment of milk and udder health through milk somatic cell count (MSCC) gave an overall mean of 134000 ±7498.7 cells/mL. Milk of Jersey cows had the highest (P<0.01) MSCC followed by Friesian-Sanga crossbred and Sanga cows in descending order. The MSCC increased (P<0.01) with increasing parity from 1 to 3. The overall total bacterial count (TBC) was 3.0×106 ± 7.4×105 CFU/mL. Cows kept in good sanitary premises had the least (P<0.01) TBC and vice versa. The overall mean for total coliform count (TCC) was 2.9×104 ± 1.4×104 CFU/mL. Jersey cows, good sanitary management and early stage of lactation (1 - 30 days) had significantly (P<0.01) reduced TCC. It is concluded that control and prevention of tick and tick-borne diseases can be enhanced for effective dairy production provided productive breed, improved farm facility, grazing management, zero grazing, enforcement of biosecurity practices, feed supplementation and weekly tick checks are given paramount attention. Commercial EIA could be used for assaying of reproductive hormones in dairy cattle. Key words: Dairying, Friesian-Sanga crossbreds, Jersey cows, tick control, tick-borne diseases prevention, cowdriosis, dermatophilosis, anaplasmosis, haemato-biochemical indices, enzyme immunoassay, reproductive hormones assay, productive traits, milk quality standards, milk somatic cell count, total bacterial count, coliform count