The graph below provides information regarding the hormonal levels during the reproductive cycle of a cow.

Question

ScanSolve AI Tutor · Accepted Answer

Here are the answers to your questions based on the provided graph:

4.3.1

Locate the "Oestrogen" (dashed line) and "Progesterone" (solid line) curves on the graph.
Find the point where these two curves intersect as they approach "Ovulation 2".
Read the corresponding "Day of cycle" value at this intersection.
The levels of oestrogen and progesterone are equal towards the onset of the second ovulation at approximately Day $\boxed{21}$ .

4.3.2
Observe the progesterone levels after Day 1.
Note the trend of progesterone levels throughout the cycle.
If the cow were pregnant, the progesterone levels would remain high to maintain the pregnancy. However, the graph shows that the progesterone level decreases significantly after Day 15-16, reaching a low point around Day 21-22, followed by a second ovulation. This drop in progesterone indicates that the corpus luteum regressed, which would not happen if the cow was pregnant.

4.3.3
Observe the trend of the progesterone level after Day 15.
Relate the progesterone level to the corpus luteum.
After Day 15, the progesterone level begins to decline sharply. This indicates that the corpus luteum has undergone luteolysis (degeneration or regression) because pregnancy did not occur.

4.3.4
Identify the events occurring around Day 0-1 (Ovulation 1).
Observe the hormone levels between Day 5 and Day 8.
Between Day 5 and Day 8, the progesterone level is rising, indicating the formation and development of the corpus luteum after ovulation. This stage of the oestrus cycle is known as $\boxed{\text{Metoestrus}}$ .

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