Milk quality Evaluation in improved collection centres. A Case study of Sululta and Chacha collection centres in Ethiopia

Abstract

The current study was carried out to investigate the quality of raw milk in highlands around Addis Ababa Ethiopia in the two collection centres: Sululta (in Amhara Region 20 kilometers north west of Addis Ababa) and Chacha( in Oromya Region 100 kilometers north east of Addis Ababa) during three different seasons (long rainy, short rainy and dry season) in farms different sizes: large farm (more or equal 10 milking cows),medium farm (between 5-10 milking cows) and small scale farms (less than 5 milking cows). Milk samples were collected and transported in ice-boxes to the laboratory of the Ethiopian Meat and Dairy Technology Institute (EMDTI) in Debre-Zeit (45 kilometers south west of Addis Ababa) and for microbial examination, while the other tests were carried out at the farm level and compared with the conventional procedures in the laboratory. Milk samples in the study were evaluated for chemical composition (fat, protein, solids non-fat and acidity), physical properties (specific gravity, freezing point degree and adulteration%) and microbiological examination(ten minutes resazurin test, total bacteria counts, gram negative bacteria counts, somatic cell counts and coliform bacteria count) . Chemical composition (fat, protein and SNF) of milk from Chacha area was higher in large scale farms during the long rainy season, while TA wasn’t significantly different (P<0.05) in all farms during the long rainy season. Regarding physical properties of milk produced in the two collection centres, there was a slight increase in specific gravity values in milk iv from Chacha during the short rainy season and dry season, while values were higher in milk from Sululta during all seasons as well as adulterations. The total bacterial counts in the dry season were higher in both collection centres (Sululta and Chacha). Whereas the values of gram negative bacteria revealed highest counts in Chacha during the long rainy season and highest somatic cell counts in the same collection centre in the short rainy season. The screenings check of coliforms revealed higher counts in Sululta than Chacha collection centre. Large scale farms revealed high protein content, SNF, acidity, specific gravity and low freezing point in all seasons, while small scale farms showed high fat content and slightly adulteration compared to other farms. Total bacterial counts were slightly higher in milk from small scale farms, while gram negative bacteria were higher in large scale farms in long rainy season and medium scale farms during the dry season, whereas somatic cell counts were slightly higher in large scale farms in the long rainy season. Season’s effect revealed the lowest fat, protein and SNF in the dry season in the different farm scales, while TA was not significantly different in the three seasons. Specific gravity and freezing point were slightly higher in milk from large scale farms during all seasons, while milk from medium scale farms was more adulterated in all seasons compared to other farms. The lowest total bacteria and higher gram negative bacteria counts was affected during long rainy season in the milk produced from large and v medium scale farms respectively, while coliforms revealed highest counts during dry season from the milk produced in the small farm scale. The results indicated that there's a significant difference (P<0.05) of total bacterial count in the interaction between the milk produced from different locations and different farm sizes and also significantly different (P<0.01) counts in the interaction between seasons× farm sizes and also in the interaction between seasons×locations ×farm sizes.The milk produced from different locations during different seasons revealed the TBC (= better quality) of the milk produced from large farm scales than the milk produced from small farms scale milk which declared a lower TBC quality, whereas the milk produced during dry season revealed a better quality than that produced in short rainy and long rainy season which ranged between (7×106 , 3×107 and 2×108 ) respectively. The gram negative bacteria in the raw milk obtained a significant (P<0.05) counts of the milk in the interactions of (seasons×farm sizes, locations×farm sizes and seasons×locations×farm sizes) where it was a better quality in the milk produced from large farm scales compared with that produced from medium and small farm scales which ranged between (6×104 , 7×104 and 7×104 ), respectively.