Physiology And Performance Losses

Fertility

Studies have confirmed that claw disorders and lameness can impact negatively upon fertil­ity. Lame cows eat less, lose weight, and are less mobile, thereby preventing active display of heat/oestrus and heat detection. A study found that cows with abscesses or sole ulcers had 63 more days open than healthy cows, while cows with two or more claw disorders had 76 more days open, compared to cows without claw disorders. Furthermore, a lower percentage of cows with abscesses or sole ulcers were pregnant at the end of lactation, compared to healthy cows.

Other studies also confirm that lameness may also impact fertility by lowering first service conception rates and increasing the incidence of ovarian cysts. In a study by Melendez (2002), cows that were clinically lame due to a claw disorder in the first 30 days postpartum had a 58.9 percent drop in first service conception rates, a 125 percent increase in ovarian cysts and an 8.2 percent decrease in pregnancy rates at 480 days postpartum. Early lactation lameness cre­ated significant concern. More than 30 percent of the cows that were lame during the first 30 days postpartum were culled before recording any reproductive event, compared to 5.4 percent of the control cows.

Sprecher et al (1997), found that compared to cows scoring 1 lub 2, cows scoring 3 or more were nearly three times more likely to have increased days to first service, 15.6 times more likely to have more days open and nine times more likely to have an increase in services per conception. Additionally, these cows were eight times more likely to be culled.

Dry matter intake and milk yield

Robinson (2001) compared milk production losses among locomotion-scored cows. Cows that scored 3 produced 5.1 percent less milk than cows that scored I. For cows scoring 4, the aver­age milk loss was 17 procent, while cows that scored 5 experienced an average milk loss of 36 procent.

In simple terms, one cause of reduced milk production is a lower dry matter intake because lame cows eat less. The lower percentage reductions (those associated with scores 2 and 3) for milk yield reflect the high priority need for energy to maintain body tissues; this means the full impact of reduced dry matter intake is not initially seen in reduced milk production.

Jednak, in an effort to sustain milk production at a higher level than is possible based only on the nutrients consumed in the diet, body reserves are mobilised, condition score decreases and milk production will decline to levels that can be sustained by the actual level of nutrients be­ing consumed. There is a negative correlation between locomotion scores and body condition scores, with body condition scores decreasing as locomotion scores increase.tabletable

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The effect of lameness on reproductive performance (Sprecher 1997)

Informacje dostarczone przez DeLaval UK