Weekly genetics review: Managing mortality and reproductive performance in young heifers

YOUNG heifers characterize one of the crucial susceptible teams in Northern Australia’s beef herds, going through vital dangers of mortality and reproductive challenges. Excessive mortality charges, significantly in first-calf heifers, can drastically cut back herd productiveness and profitability.

The Calf Alive undertaking has been instrumental in figuring out the causes of those losses and recommending methods to handle each mortality and maximise re-conception charges in younger heifers.

First-calf heifers have an inherently greater danger of mortality in comparison with mature cows. This is because of a number of physiological and management-related elements, together with:

• Dystocia (calving issue): One of many main causes of mortality in heifers, significantly youthful heifers calving for the primary time, is dystocia, usually attributable to foetal-maternal disproportion. Smaller pelvic sizes make it tough for heifers to ship calves, rising dangers of damage or loss of life for each the calf and the mom.
• Dietary calls for: Heifers are distinctive as a result of they’re nonetheless rising whereas supporting each a being pregnant and lactation. This twin demand strains their power reserves, making them extra vulnerable to well being problems and, in some circumstances, loss of life.

Key Findings from the Calf Alive Challenge:

• Age-related mortality: Heifers calving earlier than two years of age have a considerably greater danger of mortality in northern Australia, with a 4.3pc greater lacking price in comparison with non-pregnant heifers of the identical age. Even two-year-olds face 2.3pc greater mortality danger, whereas three-year-olds present a 1.6pc enhance.
• Important being pregnant standing: Being pregnant is an important issue contributing to heifer mortality. Youthful heifers have a tougher time managing the power and dietary wants required for each progress and replica.

Dietary deficiencies are a number one reason for poor reproductive outcomes and mortality in heifers. Managing the weight-reduction plan of first-calf heifers is important, particularly in areas like Northern Australia the place pasture high quality declines sharply in the course of the dry season.

Heifers, significantly these in late gestation, want considerably extra protein and power to keep up physique situation, assist being pregnant, and guarantee a profitable calving and lactation course of.

Protein and Power Supplementation:

• Protein wants: Pregnant heifers want at the least 1kg of protein per day, however dry season pastures usually present solely 500g of protein, making a extreme dietary shortfall. This lack of protein can result in malnutrition, poor progress, and better charges of dystocia, rising the chance of each heifer and calf mortality.
• Power supplementation: Throughout the dry season, heifers must be given energy-dense dietary supplements to compensate for low pasture digestibility, which generally drops beneath 55pc dry matter digestibility (DMD). This ensures they keep enough physique reserves to maintain each their progress and reproductive wants.

Bettering Physique Situation Scores (BCS):

• Goal BCS: Sustaining a BCS of at the least 3 is essential for heifers. A BCS beneath 3 considerably will increase the chances of non-pregnancy and mortality. Heifers with a BCS of lower than 3 are 2.3 to 4.1 occasions extra prone to expertise non-pregnancy and calving problems.
• Guaranteeing heifers keep a BCS above 3 improves their capability to conceive after calving and reduces mortality dangers.

Aligning Calving with Dietary Peaks:

• Timing calving with the moist season (November to April) ensures that heifers have entry to higher-quality pasture in the course of the important intervals of lactation and early post-calving restoration. Aligning calving with intervals of ample forage helps keep heifer physique situation and enhances calf survival charges.
• This strategic calving interval additionally improves the probabilities of re-conception, as heifers have extra time to get better physique reserves earlier than the onset of the dry season.

The Calf Alive research emphasises the significance of utilising knowledge on animal efficiency to make knowledgeable administration choices. By monitoring elements similar to age, being pregnant standing and mortality traits, producers can establish high-risk heifers and apply focused interventions. This consists of:

• Supplementing diets throughout important intervals (e.g., late gestation and early lactation) primarily based on Physique Situation Scores and general herd well being knowledge.
• Adjusting administration practices, similar to weaning earlier, to scale back the dietary pressure on youthful heifers.
• Implementing reproductive administration methods, like delaying the age of first calving, to permit heifers extra time to develop and mature earlier than going through the stress of being pregnant and lactation.

The findings from the Calf Alive undertaking spotlight the important want for focused administration methods to enhance the survival and reproductive efficiency of first-calf heifers. Key methods embody:

• Delaying the age of first calving to permit for better progress and cut back dangers of dystocia and mortality.
• Offering ample vitamin, significantly within the type of protein and power dietary supplements, in the course of the dry season when pasture high quality is poor.
• Aligning calving with the moist season to make sure heifers have entry to higher high quality forage throughout important intervals of being pregnant and lactation.

Genetic choice utilizing Estimated Breeding Values and genomic EBVs performs a pivotal function in bettering heifer fertility and physique situation in northern herds, significantly in difficult environments.

Utilising greater accuracy info similar to Genomic Breeding Values, together with excessive accuracy EBVs provide the chance to maneuver a herd in the direction of extra beneficial efficiency in areas similar to age at puberty and post-partum anoestrus intervals.

Alastair Rayner is the Basic Supervisor of Extension & Operations with Cibo Labs and Principal of RaynerAg.  Alastair has over 28 years’ expertise advising beef producers & graziers throughout Australia.   He could be contacted right here or by his web site www.raynerag.com.au