Raising the genetic potential of livestock

By Leonel Leal, Cibelle Torres and Sandra Paredes, Trouw Nutrition R&D

How an animal is managed in early life has an effect on the expression of its genetic potential for the rest of its productive life. That, in short, is the basis of the recently launched LifeStart program philosophy. How does it work in practice?

Since its inception, the LifeStart programme has been associated with attaining high performance in animal production, helping farms make the vital connection between neonatal animal nutrition and increased health, performance and convenience.

As a science-based company, Trouw Nutrition is extending the benefits of its programme performance to a number of species. Behind this progress are innovations and insights related to the specific metabolic functions of animal species including ruminants, swine and poultry, confirming along the way that the theoretical underpinnings of the concept translate to real advantages on farm.

Explosive population

One need only look at the explosive global population growth and the direct, and indirect, pressures it brings to people and the planet to understand the need for more efficient and sustainable farming practices. Over the next 40 years, the world will have to produce more food than it has over the last 8,000 years combined. What is more, each year, we consume 50% more resources than the planet can replenish. Even if the farming industry could keep up with this growth through traditional farming methods, environmentally it would be unsustainable. To meet the growing food needs, the industry must find ways to double food production while halving the impact on the planet.

The good news is, for much of the world, agricultural productivity is growing. For the last 20 years, this growth has come not from the intensification of inputs (increased labour and investment per ha), but from getting more output from existing resources. The chart (Figure 1) shows the sustainable advances reached in the Netherlands. In spite of these gains, the full genetic potential of livestock remains an untapped resource. Presently, the productivity of farm animals is estimated to be 30‐40% below their genetic potential due to suboptimal conditions and health status. Innovations aiming to narrow the gap between genetic potential and performance, on farm level, are needed. LifeStart is dedicated to reducing the gap to 20% by providing farmers with natural and sustainable solutions to help improve the health and performance of animals. Practice meets science How can the industry tap into this potential? In many cases, it is a matter of practice catching up with science. Take the example of dairy farming. For many years typical calf rearing practices consisted of putting newborn calves on a restricted liquid feed diet up until weaning. This helped the farmer to reduce feed costs while facilitating the transition to dry feed. It was considered, and continues to be considered in many places, if not a best practice, at the very least a 'best compromise'.

In the 1960s, however, research began to emerge suggesting that restricted diets could actually have a life-long negative impact on an animal's overall productivity. In this new light, restricted feeding was actually creating an undetected negative trade-off for the farm. Parallel situations can be found in the case of swine, poultry and other livestock –that is, nutritional shocks that were the result of logistical, economic or other external considerations were deemed acceptable, often with the notion that any early losses could be compensated for later in the animal's life.

Today, the relationship between neonatal nutrition and genetic potential has been established. Nutritional insults that were once tolerated as an inevitable part of the livestock farming process now provide us with a GPS indicating where practices must change in favour of early nutrition. The rise of epigenetics In different species, numerous research studies show that increasing nutrient supply in early life results in increased first lactation milk yields, improved performance and life span. The answer to this lies in the science of epigenetics, which refers to changes in gene expression that do not involve changes to the DNA sequence. An epigenetic change is a common and natural phenomenon induced by environmental factors. In simple terms, how an animal is managed in early life has an effect on the expression of its genetic potential for the rest of its productive life. The studies underpinning these conclusions are part of a wider body of research drawn from a broad number of species including humans, rodents, bees, swine and ruminants. In numerous situations, early nutrition, either pre-natal or post-natal, can have a programming effect on the phenotype of the offspring. The socalled 'thrifty phenotype' hypothesis, a case of 'metabolic programming' that has been validated across a large number of studies, establishes the relationship between low birth weights in human babies and a heightened incidence of type 2 diabetes. It is believed that this may be an adaptation in which malnutrition in the mother programs the offspring for a nutrient-poor future. If that future does not come about, the body is poorly adapted to handle it, particularly the processing of glucose.  

Super powered organs in dairy

Those phenotypic changes can include modifications to the size and productivity of key organs in offspring. Dr Fernando Soberon of feed and health company Shur-Gain USA, part of Nutreco, suggests: "When we compare calves fed a specific diet that enables a higher plane of nutrition pre-weaning to calves fed at a normal feeding level we find a significant difference in the development of key organs." Animals benefitting from higher nutrition prior to weaning had larger livers, kidneys and mammary glands as a percentage of body weight. "Most significantly," says Soberon, "the weight of parenchyma, the essential functional elements of the mammary gland also increased, laying the permanent foundation for a more productive life as an adult." Indeed, in a calf study measuring the effects of liquid feed intake during the first 60 days, calves fed increased levels of milk replacer registered mammary parenchymal tissue weights that were six times greater than those of calves whose milk intake was restricted. This indicates a direct effect of nutrient intake with parenchymal proliferation in the first months of life. 

High performance in pigs

Pig farming has provided an ideal test-bed for the systematic application of metabolic programming as the results are relatively easy to measure and compare. The pig industry faces unique challenges as farm and litter size expand in the relentless search for sustainable efficiency. The  aforementioned LifeStart programme has the potential to help the global swine industry take a quantum leap forward by better preparing piglets for optimal growth. To start with, the uterine environment during gestation is fundamental to optimal development of a sow's offspring. This is reflected even during embryo development, as well as later, when foetal muscle development is affected by the dam's nutritional status. Nutrition of the peri-parturient sow, and her body condition, impacts the farrowing process and colostrum production. This, in turn, provides the neonate with optimal conditions. During the first days of a piglet's life the stomach and intestines grow rapidly. To support this process, the sow's colostrum and early nutrition are essential in promoting the desired intestinal development. Moreover, pre-weaning supplements can induce accelerated maturation of the digestive system to prepare the piglet for greater and healthier growth.

In early life, the newborn pig has very few immune relevant cells in the gut and its associated lymphoid tissues. Initially, they are protected only by maternal immune factors provided through sow milk and at the moment of weaning its immune system is not yet mature. Therefore, the impact of an abrupt removal of maternal protection, coupled with stress and infection pressure, results in an immunity gap. Through the addition of functional nutrients, the immune system of the young pig can be augmented to ease transition, while reducing the need for antibiotic interventions and allowing the pig to focus all energy and nutrients for growth. Trials conducted by Trouw Nutrition show that nutrition in the early life of pigs affects overall performance. By offering milk replacer in addition to sow milk in the first two weeks after birth together with high quality diets up to six weeks of age, pigs accrue short, medium and longterm benefits. Pigs are heavier at the end of the nursery phase, advantage maintained up to slaughter; batches are more homogenous and there is a reduction in the number of days to reach slaughter weight, with higher quality carcasses. Light weight pigs, which are more prone to disease and mortality in early life, especially benefit from this strategy, with enhanced within-batch homogeneity. The impact on farm economics is significant as it leads to higher throughput and more meat produced per m2

Breakthroughs in poultry performance

In the area of poultry, the variable time between hatching and first feed means that those important nutritional windows are frequently missed, compromising the growth of chicks. While first access to feed occurs on the broiler farm, the path to that moment can be long, such that a so-called day-old chick can actually be well within their third day before feeding.

Trouw Nutrition R&D is developing different nutritional strategies in order to improve the performance of chicks starting at the earliest stages. In the hatchery, immediate access to feed in the post-hatch period has been shown to enhance tissue development (i.e., gastro-intestinal tract and immune system development). Figure 3 shows the results of different feeding strategies for recently hatched chicks. While metabolic programming and the epigenetic adaptations that underpin it have been part of scientific knowledge for some years, only now is it beginning to have practical and widespread application in the area of production animal performance. But metabolic programming requires another level of adaptation: on the part of livestock professionals. They must adapt their techniques, farm management practices, logistics and economics to a new guiding principle - that any compromise in early nutrition is ultimately a compromise in farm performance.

References available on request.