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Temporal trends in reproductive performance in Irish dairy herds and associated risk factors.

Mee JF - Ir Vet J (2004)

Bottom Line: The principal components of this trend have been an increased incidence of postpartum endocrinopathies, reduced expression of oestrus and a fall in conception rate.Significant risk factors associated with these trends have been strain substitution within the Holstein-Friesian breed and single trait selection for milk production.These phenotypic trends were attributed to both genetic and environmental factors and their interactions.

View Article: PubMed Central - HTML - PubMed

Affiliation: Teagasc, Dairy Production Research Department, Dairy Production Research Centre, Moorepark, Fermoy, Co Cork, Ireland. jmee@moorepark.teagasc.ie.

ABSTRACT
: Irish dairy herd fertility has been declining since the 1980s. The extent, nature and causes of this decline in fertility and the current status of Irish dairy herd fertility were described. An increase in calving interval of approximately one day per year has been recorded. The principal components of this trend have been an increased incidence of postpartum endocrinopathies, reduced expression of oestrus and a fall in conception rate. Both submission rate and calving-to-service interval have increased slightly over time. Significant risk factors associated with these trends have been strain substitution within the Holstein-Friesian breed and single trait selection for milk production. Critically, these changes have been reflected in loss of body condition. Contributory factors included increased herd size and possibly increased use of DIYAI. The most recent Irish study showed that 48% of cows conceived to first service and 14% of cows were not pregnant at the end of the industry-average 15-week spring breeding season. However, the top quartile of herds achieved a first-service conception rate of 59%, illustrating the wide variation between herds. These phenotypic trends were attributed to both genetic and environmental factors and their interactions. Recent Irish dairy herd fertility performance falls short of the targets set for seasonal compact calving.

No MeSH data available.


Related in: MedlinePlus

Genetic merit for milk yield in Irish dairy cows between 1989 and 1999. (Source: [30]).
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Figure 5: Genetic merit for milk yield in Irish dairy cows between 1989 and 1999. (Source: [30]).

Mentions: Although selection for milk production alone had traditionally been practised in Irish dairy herds, the rate of genetic gain was low (0.5% per year) up to the mid-1980s. However, since 1985, with accelerated strain substitution, this has increased markedly to over 1% per year [22]. There is a qualified genetic relationship between increasing genetic merit for higher milk yield (Figure 5) and reducing fertility whereby management and environment affect the relationship. For example, relatively higher-producing cows tend to be inseminated later than their lower-producing herdmates [54]. In Ireland, this relationship is affected not merely by genetic merit for milk production but also by concurrent strain substitution. Hence, the decline in fertility cannot solely be attributed to the increase in yield (Figure 6). In Ireland, the introduction of the milk quota resulted in excess dairy cows being retained in herds with consequent lower phenotypic milk yields per cow than their genetic potential might indicate as reflected in the temporal trend in genetic and phenotypic yield during the 1980s (Figure 5 and 6). Introduction of the milk quota also resulted in a low culling rate (15%) by international standards but infertility is the most common reason for culling (24%) and has increased significantly over time [43,51]. Selection for milk production alone has consistently been accompanied by reduced herd fertility due to the negative genetic correlations at cow level between these variables [22,55].


Temporal trends in reproductive performance in Irish dairy herds and associated risk factors.

Mee JF - Ir Vet J (2004)

Genetic merit for milk yield in Irish dairy cows between 1989 and 1999. (Source: [30]).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3113820&req=5

Figure 5: Genetic merit for milk yield in Irish dairy cows between 1989 and 1999. (Source: [30]).
Mentions: Although selection for milk production alone had traditionally been practised in Irish dairy herds, the rate of genetic gain was low (0.5% per year) up to the mid-1980s. However, since 1985, with accelerated strain substitution, this has increased markedly to over 1% per year [22]. There is a qualified genetic relationship between increasing genetic merit for higher milk yield (Figure 5) and reducing fertility whereby management and environment affect the relationship. For example, relatively higher-producing cows tend to be inseminated later than their lower-producing herdmates [54]. In Ireland, this relationship is affected not merely by genetic merit for milk production but also by concurrent strain substitution. Hence, the decline in fertility cannot solely be attributed to the increase in yield (Figure 6). In Ireland, the introduction of the milk quota resulted in excess dairy cows being retained in herds with consequent lower phenotypic milk yields per cow than their genetic potential might indicate as reflected in the temporal trend in genetic and phenotypic yield during the 1980s (Figure 5 and 6). Introduction of the milk quota also resulted in a low culling rate (15%) by international standards but infertility is the most common reason for culling (24%) and has increased significantly over time [43,51]. Selection for milk production alone has consistently been accompanied by reduced herd fertility due to the negative genetic correlations at cow level between these variables [22,55].

Bottom Line: The principal components of this trend have been an increased incidence of postpartum endocrinopathies, reduced expression of oestrus and a fall in conception rate.Significant risk factors associated with these trends have been strain substitution within the Holstein-Friesian breed and single trait selection for milk production.These phenotypic trends were attributed to both genetic and environmental factors and their interactions.

View Article: PubMed Central - HTML - PubMed

Affiliation: Teagasc, Dairy Production Research Department, Dairy Production Research Centre, Moorepark, Fermoy, Co Cork, Ireland. jmee@moorepark.teagasc.ie.

ABSTRACT
: Irish dairy herd fertility has been declining since the 1980s. The extent, nature and causes of this decline in fertility and the current status of Irish dairy herd fertility were described. An increase in calving interval of approximately one day per year has been recorded. The principal components of this trend have been an increased incidence of postpartum endocrinopathies, reduced expression of oestrus and a fall in conception rate. Both submission rate and calving-to-service interval have increased slightly over time. Significant risk factors associated with these trends have been strain substitution within the Holstein-Friesian breed and single trait selection for milk production. Critically, these changes have been reflected in loss of body condition. Contributory factors included increased herd size and possibly increased use of DIYAI. The most recent Irish study showed that 48% of cows conceived to first service and 14% of cows were not pregnant at the end of the industry-average 15-week spring breeding season. However, the top quartile of herds achieved a first-service conception rate of 59%, illustrating the wide variation between herds. These phenotypic trends were attributed to both genetic and environmental factors and their interactions. Recent Irish dairy herd fertility performance falls short of the targets set for seasonal compact calving.

No MeSH data available.


Related in: MedlinePlus