With regard to pullet body weight and layer performance, sexual maturity is directly correlated with the onset of the production cycle. Flock uniformity at sexual maturity allows producers to have a sooner start of production, higher peak lay, and better persistency of egg production. Another advantage of having flocks with uniform body weights is the ability to easily meet the nutrient requirements for the entire flock with one diet. Ideally, the uniformity of body weights within a particular flock should be close to 85%. Pullets with body weights that are too low tend to reach sexual maturity later and produce less eggs over their lifetime than heavier birds. Furthermore, pullets not achieving target body weight could demonstrate poor physiological and anatomical conformation particularly in the gastrointestinal and reproductive systems.

Off target

There are several consequences of having body weights that exceed the target during the growing period. Obese hens do not have normal vaginal mucosa retraction and often prolapse, thus exposing them to pecking by other birds. This abnormality leads to increased mortality and early reduction of egg production. Other undesirable consequences, such as increased basal nutritional requirements and higher production of non-marketable eggs, may consequently reduce profitability.

Phytogenic Feed Additives

Phytogenic feed additives (PFA) have shown positive effects on gastrointestinal anatomy and physiology and nutrient digestion and absorption. These positive effects are due to increased production of pancreatic enzymes, improvement in intestinal integrity, and augmented bile secretion. Pancreatic enzymes aid in the digestion of nutrients such as lipids, carbohydrates, and amino acids in the intestinal lumen. By optimising nutrient digestibility and improving intestinal morphology, nutrient absorption is also enhanced. Overall, phytogenic feed additives improve nutrient utilisation, thus allowing more nutrients to be utilised by the bird to reach the ideal body weight. Phytogenics are also able to decrease the amount of pathogens in the gastrointestinal tract. The increased digestibility when phytogenic are used leads to a decrease in the free protein in the lumen of the intestine, diminishing the pathogens prevalence.

Probiotics

Probiotics stabilise the gastrointestinal microbiota by preventing the colonisation of pathogens such as Escherichia coli, Salmonella, and Clostridium, supporting immunity against microbial and environmental insults, and enhancing intestinal integrity. The efficacy of probiotics may be modified by the amount and kind of strains being utilised. Often times, several strains used in conjunction can be more effective than a single one. Some of the beneficial effects caused by probiotics include enhanced nutrient absorption due to increased length and width of the intestinal villi and augmented secretion of important digestive enzymes such as amylase. Additionally, several studies have demonstrated that birds fed diets supplemented with probiotics display an enhanced immune response against pathogens and better performance than supplemented birds.

Figure 1. Ideal body weight uniformity.

Source: Hy-Line International, Technical Update: Growing Management of Commercial Pullets www.hyline.com/userdocs/pages/TB_PULLET_MGMT_ENG.pdf

Organic Acids
Animal feed has been identified as a notable carrier for numerous bacteria that can cause health issues not only for the animal ingesting the contaminated feed, but also humans who may come in contact with products from those infected animals. Feed can become contaminated by pathogens during harvest, handling processes, transportation, processing, and storage. Once ingested, bacterial pathogens can gain access to the gastrointestinal tract and cause tremendous investment of metabolic energy and loss of performance. For many years, science has shown that organic acids can reduce bacterial load in animal feed. The mechanisms by which organic acids exert their beneficial effects include their ability to disrupt intracellular pH regulation, thus causing cell death, reduce intestinal pH, creating an environment unsuitable for pathogenic growth, and enhance digestive enzyme activity. Through these mechanisms, organic acids reduce pathogenic burden in the intestine and promote growth and improved performance in birds.

Pullets with body weights that are too low tend to reach sexual maturity later and produce less eggs over their lifetime.

Costs of Inflammation

Intestinal health is fundamental to achieving and maintaining ideal body weight. Intestinal health may be disrupted by several situations such as pathogenic challenge, poor quality feed ingredients, and environmental stressors. These insults may trigger intestinal inflammation, which results in expensive costs in the physiological economy. When challenged with inflammatory processes, the body has less energy to spend because of lowered energy intake due to anorexia; on the other hand, energy expenditure is higher because of the increased metabolic rate caused by inflammation. Fortunately, nature offers some tools that are able to counteract the negative effects of inflammation. Phytogenic feed additives and probiotics have shown to be effective in optimizing nutrient digestibility and absorption and feed conversion.

Phytogenic feed additives, organic acids, and probiotics in combination are able to optimise nutrient digestion and absorption, reduce pathogenic load in the intestine, modulate the immune response, and improve gastrointestinal integrity.

Summary

Effective digestion, absorption, and investment of nutrients leads to the achievement of target pullet body weight and increased flock uniformity. Optimal production onset, peak, and persistency will occur only in pullets with ideal and uniform body weights. Furthermore, appropriate body structure and physiology lead to the production of more marketable eggs. Overall, these features ultimately determine the production cycle profitability.

Phytogenic feed additives, organic acids, and probiotics in combination are able to optimise nutrient digestion and absorption, reduce pathogenic load in the intestine, modulate the immune response, and improve gastrointestinal integrity. Thus, these novel feed additives may allow the relocation of resources from immunological responses against insult towards anatomical development and ideal body weight in pullets.