Extended Lactation Persistency in Dairy Goats

Extended Lactation Persistency in Dairy Goats

Clive Pickering Clive Pickering

Clive Pickering

Dairy Goat Breeding Acceleration Program to Improve Genetic Quality and Milk Production in Indonesia

发布日期: 2024年9月21日
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Lactation persistency refers to the ability of a dairy goat to maintain consistent milk production throughout the lactation period, after reaching peak milk yield. Unlike standard lactation cycles where production declines sharply after peak, goats with high lactation persistency show a more gradual reduction in milk yield. This trait is particularly valuable in dairy goat production systems, where extended lactation can reduce labor, breeding costs, and overall herd management complexity.

Lactation cycles in Indonesian dairy goats typically last around 220 days. However, with extended lactation, this period can stretch to 400 days or more without a significant drop in production. The ability to maintain milk yield for extended periods offers both biological and economic advantages.

Mechanisms Behind Extended Lactation Persistency

  1. Hormonal Regulation During lactation, various hormones regulate milk production, with prolactin, oxytocin, and growth hormone playing central roles. Prolactin is key to initiating and sustaining lactation, while oxytocin is responsible for milk letdown. Goats with genetic variants that enhance the response to prolactin and other lactogenic hormones tend to show greater lactation persistency. For instance, mutations or polymorphisms in the prolactin receptor (PRLR) gene can alter the sensitivity of mammary glands to prolactin, allowing them to continue producing milk longer (Azzarelli et al., 2021).
  2. Genetic Contributions

Kappa-casein (CSN3) gene: This gene influences the production of casein proteins in milk. Specific variants of this gene are associated with not only higher milk production but also extended lactation cycles (Sharma et al., 2020).

Growth hormone receptor (GHR) gene: Variants of the GHR gene enhance the metabolic efficiency of dairy goats, promoting prolonged milk production by improving the energy balance of the animal (Zhang et al., 2019). This gene regulates tissue growth and milk production, with specific alleles linked to higher lactation persistency.

Oxytocin receptor (OXTR) gene: Responsible for the sensitivity of mammary tissues to oxytocin, this gene influences milk ejection. Goats with certain OXTR gene variants show improved letdown efficiency throughout extended lactations (Leroy et al., 2020).

  1. Milk Production and Energy Balance The ability of a goat to maintain a positive energy balance is essential for lactation persistency. After the peak of lactation, energy demands for milk production remain high. Goats with extended lactation persistency tend to have a better ability to metabolize nutrients efficiently. Variants of the growth hormone receptor (GHR) gene and other Extended Lactation Persistency in Dairy Goats: A Detailed Breakdown

Introduction to Lactation Persistency

Lactation persistency refers to the ability of a dairy goat to maintain consistent milk production throughout the lactation period, after reaching peak milk yield. Unlike standard lactation cycles where production declines sharply after peak, goats with high lactation persistency show a more gradual reduction in milk yield. This trait is particularly valuable in dairy goat production systems, where extended lactation can reduce labor, breeding costs, and overall herd management complexity.

Lactation cycles in dairy goats typically last around 300 days. However, with extended lactation, this period can stretch to 400 days or more without a significant drop in production. The ability to maintain milk yield for extended periods offers both biological and economic advantages.

Mechanisms Behind Extended Lactation Persistency

  1. Hormonal Regulation During lactation, various hormones regulate milk production, with prolactin, oxytocin, and growth hormone playing central roles. Prolactin is key to initiating and sustaining lactation, while oxytocin is responsible for milk letdown. Goats with genetic variants that enhance the response to prolactin and other lactogenic hormones tend to show greater lactation persistency. For instance, mutations or polymorphisms in the prolactin receptor (PRLR) gene can alter the sensitivity of mammary glands to prolactin, allowing them to continue producing milk longer (Azzarelli et al., 2021).
  2. Genetic Contributions
  3. Milk Production and Energy Balance The ability of a goat to maintain a positive energy balance is essential for lactation persistency. After the peak of lactation, energy demands for milk production remain high. Goats with extended lactation persistency tend to have a better ability to metabolize nutrients efficiently. Variants of the growth hormone receptor (GHR) gene and other metabolic-related genes may contribute to a more stable energy balance, preventing the typical decline in milk production seen in shorter lactations.
  4. Mammary Gland Involution In most dairy goats, mammary gland involution (the process by which the mammary glands shrink and reduce milk production) begins after peak lactation, leading to a rapid decline in milk yield. However, goats with higher lactation persistency experience a delayed or less pronounced involution process, allowing them to maintain production for longer periods. The STAT5 signaling pathway, activated by prolactin, plays a critical role in delaying mammary gland involution, and polymorphisms in genes affecting this pathway have been linked to extended lactations (Watson et al., 2022).

Economic Advantages of Extended Lactation Persistency

  1. Reduced Breeding Frequency and Reproductive Costs Goats with extended lactation persistency do not need to be bred as frequently to maintain high milk yields. This reduces the costs associated with breeding, including the expenses for semen, veterinary care, and the resources required to manage pregnancies and young kids.
  2. Lower Replacement Costs Frequent culling of goats that experience early declines in milk production can be a major financial burden. Extended lactation persistency allows producers to retain productive goats for longer periods, reducing the need for constant herd replacement. This lowers replacement costs, including the expense of raising new kids to reproductive maturity.
  3. Increased Milk Yield per Lactation Cycle Dairy goats with high lactation persistency produce more milk over a single lactation cycle compared to goats with shorter, less persistent lactations. For instance, a goat that can maintain 85% of its peak production for an additional 100 days will generate significantly more milk, leading to higher total milk output without the need for additional animals.
  4. Feed Efficiency Goats with extended lactation cycles tend to use feed resources more efficiently over time. Instead of using feed primarily for reproduction and growth of kids, more energy from feed is directed toward milk production. This improved feed conversion ratio reduces the overall cost per liter of milk produced.
  5. Labor and Management Efficiency Farms that adopt a strategy of extended lactation cycles often experience lower labor demands. With fewer breeding and kidding events, farm staff can focus on other operational tasks, streamlining herd management. The reduced need for reproductive management can also free up resources for genetic selection and improvements in milk quality.

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Practical Considerations for Implementation

  1. Genetic Selection Selective breeding programs should focus on identifying and propagating goats with favorable genetic markers for lactation persistency. Genomic selection tools can help farmers identify the best candidates for breeding. Crossbreeding programs may also introduce beneficial traits for extended lactation from other breeds known for high persistency, such as the Saanen or Alpine breeds.
  2. Nutrition Management Goats with extended lactation cycles require careful nutritional management to ensure they maintain a positive energy balance. High-quality forage, combined with concentrates rich in energy and protein, is essential to sustain prolonged milk production. Balancing macronutrients is critical to prevent metabolic disorders, which can lead to premature declines in milk yield.
  3. Monitoring and Record-Keeping Regular monitoring of milk yield and body condition is essential to track persistency and overall health. Record-keeping systems that document lactation curves, feed intake, and reproductive events will help producers make informed management decisions. Data-driven approaches to managing extended lactation can further enhance profitability by identifying trends and improving herd performance over time.

The future of Extended Lactation

Extended lactation persistency in dairy goats is a valuable trait that can significantly improve both biological efficiency and economic returns. By understanding the genetic mechanisms involved and adopting best management practices, dairy goat producers can benefit from increased milk yields, reduced costs, and improved herd health. Future research into the specific genetic markers and physiological processes that influence persistency will further enhance the ability to select and manage goats for extended lactation cycles.


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