Thesis

ABSTRACT: Teat w i s e screening of individual m i l k s a m p l e s f r o m 16 c o w s situated a t college dairy and 69 crossbred c o w s sltuated a t TTD farm w e r e done using CMT and SLST test. B a s e d upon gel f o r m a t i o n m i l k samples w e r e graded into negative, doubtful, 1+. 2+ and 3+. The proportion of ~verall'ne~ativt eea t s i n the population w e r e 57.8, 67.96% and doubt w e r e 9.58 and 8.53% as revealed by CMT 1 and SLST test respectively. Irrespective of the position of teats the frequency of negativee i n the population w e r e h i g h e s t , next i n the descending order w e r e I+, f and the least w e r e 2+ or 3+. Breed w i s e studies showed that jersey breed was highly resistant t o subclinical mastitis being maximum proportion of population showed negative followed by HF and miscellaneous breeds and the lowest were FB crosses of the college dairy farm. Somatic c e l l count between CMT and SLST t e s t in different grades of subclinical mastitis milk showed no difference concluding any one - t e s t was equally good. Highly significant differences were observed between grades in a l l the parameters namely SCC, SPC, chloride content and pH and a l l are showing ascending with increase in grade of milk. However COB t e s t showed no coagulation and RRT showed significant difference between the grades both in college as well as TTD farm. The milk samples graded 1+ and abwe exceeded the l i m i t s of quality in a l l the parameters requiring rejection of milk samples salvaging doubtful cases t o some extent. The parameter studies of t e a t w i s e samples showed no significant differences between the position of teats and breeds similar were the cases with age wise studies, lactation numbers, stage of lactation and farms indicating these factors were not influencing the parameters to a signi f ican t extent. There was no correlation between two parameters stuaied so f a r except i n two cases i n college dairy farm. Shelf l i f e studies of different grades of subclinical mastitis milk and control milk samples stored a t room temperature showed no significant variation i n the levels of acidity be tween a torage timing but significant dif f erences i n RRT between timings and tendency to coagulate on heating i n 9th hour storage onwards indicating the pattern of quality of milk stored a t room temperature. Refrigerated storage samples showed significant degradation of quality from 36 hour storage onwards. Mixed milk samples stored a t room temperature showed significant difference between different grades as well as between storage timing in the estimates of t i t r a t a b l e acidity and only between storage timings i n the estimates of RRT the pattern of variation revealed mixing of each grade of milk into normal milk decreased the tendency of acid production beyond 9th hour storage i n a l l proportions. Refrigerated storage of mixed milk samples showed the lowering acidity a t 72 hour of incubation to a level a t 12 hour storage w i t h decreasing RRT. A definite reduction of acidity was indicated as storage time advances 48 hour and above with s l i g h t decrease i n RRT due to possible proliferation of Psychrophilics and s i m u l - taneous reduction of acid producing mesophilics. . Shelf .life..of curd samples of d i f f e r e n t grades of subclinical mastitis milk and normal milk kept a t room temperature reveals s i g n i f i c a n t t o highly siqnificant differences i n the means of a c i d i t y between grades as well as between t i m e intervals. The finding that decrease i n a c i d i t y a t 12th hour indicated the upper l i m i t of shelf l i f e of curd at room temperature. Curd samples stored a t r e f r i g e r a t i o n temperature showed s i g n i f i c a n t &iff erence in a c i d i t y between grades and intervals and highly s i g n i f i c a n t r e s u l t s in curd tension between grades only indicating the pattern of quality of milk curd was good upto 24 hour storage as long as the a c i d i t y was increasing phase irrespective of the grades. It would be concluded that the grades of subc l i n i c a l mastitis milk 1+ and above require t o t a l rb jsction on par with mastitis milk samples. Routine t e s t i n g of the t e a t with milk samples is necessary using e i t h e r CMT or SLST t e s t which ever i s available i n addition t o s t r i p cup t e s t t o eradicate the daily Samples showing 1+ and above grades of subclinical mastitis. Only 50-60% of population showing negative quarters i n the population showing negative could be milked safely and those doubtful cases salvaged i f necessary and others should be discarded outrightedly. Proper package practices should be restored for improving the udder health and the milk quality i n the present production systems for the supply of milk and i n the preparation of fermented milk and milk products. Further studies are necessary t o find out exact. bacteriological picture of different grades of milk t o come up with further conclusions.

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