# In-Class Activity: New Born and Calf Nutrition

*Part I - Instructor's notes:*

- Colostum is not milk. As opposed to the definition of colostrum presented in the reading, calf experts have recently revised its definition as the mammary gland secretion collected at the first milking after calving.
- Intestinal “openings” really refers to the passage of macro-molecules through the intestinal epithelial cells.
- By the way, if the concentration of IgG in colostrum averages 59.8 mg/ml (or 0.0598 g/ml) and colostrum specific gravity is 1.05, (i.e., 1.05 g/ml), then colostrum contains 0.0598 g of IgG per 1.05 g of colostrum; or 0.0569 g per g; or 5.69 g per 100 g. In other word colostrum contains 5.7% IgG.
- Notice that there were some discrepancies between the “extension publication (Ch 3) and the NRC, as to the amount of starter consumption recommended to wean a calf successfully.
- Contrarily to the statement at the bottom of page 26, a calf is NOT born a ruminant. Chewing activity in a calf begins when the rumen has developed to a point at with the ingestion of solid feeds contributes to nutrient supply.
- Average numbers are “dangerous” to use. The study of Levieux and Ollier (1999) showed the colostrum IgG in 60 Holstein cows averaged 59.8 mg/ml, but the standard deviation was 28.5 mg/dl. Large variations were recorded for IgG concentrations (15.3–176.2 mg/ml) and yields (0.2–925 g).

*Part II - Understanding Variation (Importance of understanding a standard deviation):*

__Question 1:__ What is the probability that a colostrum sample contain more than the average of 59.8 mg/ml of IgG?

__Question 2:__ What is the probability that a colostrum sample contain less than 25 mg/ml of IgG?

__Question 3:__ What is the probability that a colostrum sample contain more than 100 mg/ml of IgG?

__Question 4:__ Compare the probability for a colostral IgG test to return a value of 59.8 (say 60) mg/ml (i.e., the mean) when the standard deviation is either 28.5 mg/dl (about half the mean) or 5.98 mg/ml (i.e., about one tenth of the mean)? Explain your finding.

__Question 5:__ Compare the probabilities of finding a colostrum with less than 40 mg/ml if the standard deviation is 5.98 mg/ml versus 28.5 mg/ml)

__Question 6:__ Given the standard deviation of 28.5 mg/ml, what the expected range that will include 68% of the samples?