Lab Test Flashcards
What is one of the best tools available for the dairy fieldman?
The microscope
The microscope is used to study bacterial types in milk.
What can careful study of bacterial types in milk tell you?
Much about its bacterial quality
This analysis is important for assessing milk safety and quality.
What type of reference have dairy fieldmen often requested?
A collection of photomicrographs
These images assist in the microscopic evaluation of milk.
What do stained smears indicate in milk evaluation?
The history of a milk sample
They are useful but should not be the sole criterion for quality.
True or False: No single test can provide a complete picture of the bacteriological history of milk.
True
Multiple tests are necessary for thorough evaluation.
What can affect the meaningfulness of deductions about milk quality?
Accurate sampling and proper care of milk samples
Poor practices can lead to misleading results.
What are vacuoles in milk caused by?
The removal of fat droplets from the dried milk solids
They appear as white circular areas against a blue background.
What should good quality milk never show in large numbers?
Leucocytes or bacterial cells
Occasional presence is acceptable, but not in large quantities.
What is a characteristic of mastitis milk?
Presence of long-chain Streptococcus agalactiae and associated leucocytes
These indicate infection and poor milk quality.
What can the use of a strip cup reveal in mastitis milk?
Flaky particles (garget)
This is a sign of milk quality issues due to udder damage.
Fill in the blank: Good quality milk may contain an occasional _______ or bacterial cell.
leucocyte
Good quality milk should not have large numbers of these cells.
What type of streptococci is associated with massive numbers of leucocytes in milk?
Short-chain streptococci and long-chain Streptococcus agalactiae
These organisms indicate an infection that may affect milk production in cows.
What is phagocytosis?
The actual engulfing of bacterial chains by leucocytes
This process is part of the immune response to destroy pathogens.
In mastitis-infected cows, how many quarters may yield infected milk?
One or two quarters
The remainder of the udder may still produce normal milk.
What characteristic grouping is typical of staphylococci?
Irregular groupings resembling a clump of grapes
This morphology is indicative of staphylococcal infection.
What are the common sources of staphylococci contamination in milk?
Contact with residues in open seams and crevices of utensils
Poor sanitation practices lead to contamination from milking equipment.
What may cause the presence of clumps of staphylococci in milk?
Improperly cleaned milking machines or rubber parts
Hygiene practices are crucial to prevent bacterial contamination.
What type of cell growth is associated with contaminated utensils?
Mixed cell growth
This includes clumps of staphylococci, diplococci, yeasts, rods, and chains.
What can cause the same bacterial picture as contaminated utensils in milk?
Contamination by dust
Environmental factors can also contribute to milk contamination.
What do paired round cells (diplococci) or short chains of round cells (streptococci) indicate in milk?
Poor cooling
This is typically associated with Streptococcus lactis, the sour-milk organism.
What does a milk sample on the verge of souring show under the microscope?
Many pairs of cells, double pairs, and short chains with a high bacterial count
This indicates that the milk is almost sour.
What does a mixed bacteria field in milk suggest?
Poor production methods
It shows clumps of micrococci, short chains, and paired bacilli, indicating contamination.
What impact does contamination have on milk quality?
It can ruin the quality of a large volume of milk
The lowered quality persists in pasteurized or manufactured products.
Fill in the blank: The presence of _______ in milk usually indicates poor cooling.
paired round cells (diplococci)
