Module 22 CAT Ciara McKay

Plot the postpartum diseases pattern - incidence per month

Calculate:

a. Ovarian cysts incidence by fresh month and plot within the graph of postpartum

diseases

b. Ovsynch + CIDRsynch usage (% used at first AI) per month and plot this within the

graph of postpartum diseases

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Incidence of Post Partum Disease by Month

Metritis Incidence Milk Fever Incidence RFM Incidence

LDA Incidence Ketosis Incidence

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Incidence of Post Partum Disease by Month with Dotted Lines Indicating Ovarian Cyst Incidence and Ovsynch & CIDRsynch Usage

Metritis Incidence Milk Fever Incidence RFM Incidence

LDA Incidence Ketosis Incidence Ovarian Cyst Incidence

Ovsynch & CIDRsynch Usage

c. Over whole period: the conception rate (CR) % at first AI for Ovsynch+CIDRsynch

and for cows standing to be mounted (build a 100% stacker column graph,

indicating number of pregnant and open animals).

Reflection on results:

1. Give 1x reason for Ovarian cysts results

- Incidence of ovarian cysts first increased in January 2015, with a steady increase being seen

then on up to July 2015. This increase in ovarian cysts can be linked to the increased

incidence of ketosis and metritis postpartum, both occurring from the December 2014

onwards. It has been shown in literature that incidence of ovarian cysts is increased by

concurrent disease in the postpartum period. Interestingly, the increase in postpartum

ketosis and metritis coincides with the change in diet adopted on farm in December 2014.

Alfalfa hay which was previously used is highly digestible, high in crude protein and is also

high in energy. In comparison, the newly introduced timothy hay is lower in crude protein

and energy, and is also less digestible. It is likely that the introduction of the new diet, with

reduced protein and potentially reduced dry matter intake (DMI) has predisposed the dairy

cows to disorders of energy balance (leading to increased ketosis) and disorders of the

immune system (leading to increased metritis), and thus increased incidence of ovarian

cysts.

2. Give 2 reasons for the synchronization protocols incidence results

Reason 1:

- Ovsynch & CIDRsynch usage increased on farm from January 2015, where 54% incidence

was noted and remained high throughout the year up to September 2015. This likely relates

to a low submission rate caused by the increased incidence of postpartum disease over the

same time period, as it is proven that any transition disease has the potential to reduce

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Standing to be mounted Ovsynch & CIDRsynch

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Conception rate (CR) at first AI for cows standing to be mounted and for Ovsynch & CIDRsynch

Pregnant Non-pregnant

submission rate. Synchronisation on farm increased in order to overcome low submission

rate by timing oestrus/ovulation in all cows.

Reason 2:

- The increased incidence of ovarian cysts from January 2015 onwards can also account for

the increased use of synchronisation protocols over this same period. It is known that cystic

ovaries prolong the calving to first service interval, meaning cows with ovarian cysts will not

start cycling at the same time as their healthy herdmates. It can be noted specifically that

use of CIDRsynch increased in the months where cyst incidence increased as this is the

protocol of choice for treating ovarian cysts.

3. Analyse the conception rate results:

i. What is your subjective evaluation of CR results?

- Conception rate for cows standing to be mounted is 41% and is higher than the

conception rate for cows on the Ovsynch & CIDRsynch protocols, which is 26%. The

conception rate for those standing to be mounted is within the target range for this

type of dairy farm, but the conception rate for those on the synchronisation

protocols is below target.

ii. Do the results fit with what you know from the literature?

- Yes as literature suggests use of synchronisation protocols can reduce conception

rate.

iii. Give 1 possible reason for your evaluation of CR results.

- Ovsynch has been proven to reduce conception rate.

- In an ideal situation, the 1st GnRH injection in Ovsynch causes ovulation of an old

dominant follicle and allows a new, highly fertile dominant follicle to form. This

situation relies on administering correct doses of GnRH at 1st injection, stage of cycle

(progesterone concentration affects GnRH) and most importantly, need to have a

dominant follicle present in the first place that will ovulate following GnRH1.

- The problem with reduced conception rate occurs when the Ovsynch protocol is

started at the wrong time. If we begin the Ovsynch protocol when a follicular wave

has just emerged, there is no dominant follicle present to respond to the 1st GnRH

injection. Instead, the dominant follicle emerges days later and may become atretic.

The 2nd GnRH injection is given at a time where there is no dominant follicle present

and thus no ovulation cannot occur. Fixed time AI is scheduled for after the 2nd

GnRH injection but if the cow has not ovulated she cannot conceive and thus

conception rate will be poor.