Prevalence and Clinico-Pathology of Ketosis in Dairy Cows in Tigray Region of Ethiopia

An investigation to study the prevalence and clinico-pathology of ketosis in dairy cows was undertaken from November 2007 to May 2008 at Kalamino, Agazi and Mekelle University dairy farms in and around Mekelle town of Tigray region of Ethiopia. Recentlycalved cows were screened for ketosis by subjecting urine and milk sample to strip (URS-10) and Rothera’s tests. An overall prevalence of 12.29% was recorded with highest prevalence during January and February. Age-wise, the highest prevalence was noticed at 8-9 years of age (73.34%). Cows in their 4th lactation (46.67%) and those in 1-2 months (53.35%) of lactation had significantly higher prevalence (p< 0.005). The clinical observations in ketotic cows were anorexia, refusal to take concentrate and decrease in milk yield. There was 30-100% decrease in milk yield in most of the cases. The body temperature, pulse and respiration rates were within normal range with decreased rumen motility. Feces were scanty, mucoid and dry; and urine, breath and fresh milk had characteristic smell of acetone. Ketotic animals were treated with dextrose and insulin.


INTRODUCTION
Ketosis, (acetonemia) has been recognized as one of the main important metabolic disorders in dairy cows.It is caused by impaired metabolism of carbohydrate and volatile fatty acids that lead to excessive production of ketone bodies: acetoacetic acid, beta-hydroxybutric acid and their decarboxylation product such as acetone and isopropanol (Radostits et al., 2000).
A high prevalence of clinical and sub-clinical ketosis has been recorded in recently-calved highyielding dairy cows in many countries (Mcsherry, 1977).But little work has been done on ketosis in dairy cows in Ethiopia which comprise about 42% of the total cattle herds and any disease related to production causes a heavy loss to the farmers (FAO, 1993).Therefore, the present investigation was under-taken to record the prevalence and clinico-pathology of clinical ketosis in cattle dairy farms in and around Mekelle town of Tigray region of Ethiopia.

Study Design
The study involved a cross-sectional observation in a multi-stage sampling technique to estimate the prevalence of bovine ketosis in recently calved dairy cows.A total of 122 milking cows were screened for clinical ketosis from November 2007 to May 2008.

Study Animals
In this study, Holstein-Friesian (HF) cross-bred cows were examined.Questionnaire data such as age, lactation number, stage of lactation, milk-yield, nutritional condition (feeding), symptoms observed including by owners and the past and present history of illness.Clinical examination of cows such as body temperature, respiration and pulse rates including ruminal motility were thoroughly carried out.The systems examined and how they performed is indicated in table.2.

Assay of Ketone bodies
Fresh urine and milk samples were collected and tested for ketone bodies.The diagnosis of clinical and subclinical ketosis was confirmed with the help of different qualitative and quantitative tests with urine and milk (Kaneko, 1989).The ketone bodies in urine were detected using reagent strips (URS-10) which react with aceto-acetic acid but not with acetone and betahydroxybutyric acid.Rothera's test was performed with both urine and milk and their sensitivities were compared.Rothera's test detects acetone and aceto-acetate but not betahydroxybutyric acid (Kaneko, 1989).
The clinical observations in ketotic cows are shown in tables 1 and 2. The first characteristic clinical signs observed were partial or complete anorexia, refusal to concentrate and decrease in milk yield.The decrease in milk yield was 36-100% in 5 cases followed by 30-36% in 5 cases and less than 30% in another 5 cases.
The body temperature, respiration and pulse rates were within normal range with decreased ruminal motility.On rectal examination feces were scanty, mucoid and dry in most cases.The cows appeared dull and depressed with a smell of acetone in breath, urine and fresh milk.The mucous membranes were slightly congested.Nervous signs were seen in one case which showed salivation, licking of body and inanimate objects and grinding of teeth (Table 2).Ketotic animals were treated with 50% dextrose intravenous and insulin and resulted in the disappearance of ketone bodies from the milk and urine post treatment.

DISCUSSION
Among the production diseases in dairy animals, ketosis occupies an important place as it mostly affects the high-yielding animals causing a heavy loss to the farmers, particularly during recently calving stage.In Ethiopia the study of epidemiology, clinico-pathologhy, diagnosis and treatment of ketosis in cows has not been well-documented and literature on ketosis is still scanty.Hence the present investigation was undertaken to study the prevalence, clinicopathologhy and diagnosis of clinical and sub-clinical ketosis in dairy cows.
In the present study an overall prevalence of 12.29% was recorded for clinical ketosis from November 2007 to March 2008.This might be due to the highest calving rates of the animals during period as reported by the farm management personnel.A prevalence of 10.4% and 13.1 % has been reported for clinical ketosis and 33.8% for sub-clinical ketosis by Flemming (1996).
Age-wise, highest prevalence of ketosis was recorded in cows of 8-9 years (73.34%)The present observation is in agreement with the findings of Turner (2008) who reported a high prevalence during advanced age.
Lactation-wise the highest prevalence of ketosis was recorded during 4th lactation with greater frequency in 1-2 month post-partum.The Data showed a significant correlation (P< 0.05) and difference between prevalence of ketosis with age, lactation number and stage of lactation.This is due to maximum productivity of animals during this period (Baird, 1982;Turner, 2008).
Analysis of sensitivity indicated that in the first few days of lactation the rate of nonesterified fatty acid utilization had a greater effect on ketone body concentration in periparturient cows than the other parameters tested in a model (Guo and Kohn, 2008).The present investigation showed highest prevalence during 1-2 month (53.3%) post-partum followed by 0-1 month (20%), 2-3 month (13.3%) and 3-4 and 4-5 (6.67% each).This is because in this stage the cows are in negative energy balance from calving until the peak lactation is reached, the demand on endogenous nutrient store for energy which increases the susceptibility to ketosis (Radostits et al., 2000).
Clinical ketotic cows showed anorexia, refused to take concentrate, decrease in milk yield and rapid loss of condition.Baird (1982) reported that the decrease in body weight could be caused by rapid mobilization of adipose tissue and also production stores.Milk production of ketotic cows decreased by 36-100% in five cases and followed by 30-36% in another five cases and less than 30% in five cases.It may be due to heavy drainage of lactose through milk to meet the demand of heavy lactation and depends on endogenous nutrient stores and so milk-yield becomes decreased.Anderson and Lundstrom (1985) suggested that increase in ketone bodies in blood may cause a decrease in milk yield.Clinical cases were treated with dextrose and insulin.
As a result, no ketone body was found in milk and urine samples post treatment.This is in line with the results of Otto et al. (2007) who reported a marked improvement in ketotic cows.The body temperature, respiration and pulse rates were within normal range while ruminal motility was decreased.These observations are similar to the studies reported by other workers (Baird, 1982;Turner, 2008).The present communiqué conclude that recently calved cows should be routinely examined for ketosis so as to avoid production losses to dairy owners.

ACKNOWLEDGEMENT
The authors would like to acknowledge the college of Veterinary Medicine, Mekelle University, for enabling them to do this research.Thanks are also due to the reviewers whose constructive comments have improved the paper.

Table 1 .
Clinical observations (lactation) in cows suffering from clinical ketosis. S.

Table 2 .
Clinical observations (lactation) in cows suffering from clinical ketosis.