Olfactory Imprinting Effect:

The “Innate Navigation SystGiven the current state of swine production, considerable attention has been directed toward enhancing sow reproductive performance and fostering post-weaning growth in piglets; however, the intricate interplay between sows and their offspring has often been overlooked. This oversight frequently results in heightened stress responses and diminished disease resistance in piglets following weaning. In reality, the sow-piglet bond constitutes a complex biological process, involving profound physiological, behavioral, and emotional connections between the mother and her offspring.

Taking the practice of cross-fostering as an example, the congruity of olfactory signals emerges as a pivotal factor determining the success rate of the procedure. Metabolic byproducts—such as secretions from sebaceous glands on the piglet’s skin, saliva, and urine—combine with maternal substances—including milk and reproductive tract secretions—to form a distinct “parent-offspring olfactory recognition system.” These biologically active, trace chemical signal molecules are classified as pheromones; they facilitate signal transmission through two primary pathways—airborne diffusion or direct physical contact—thereby precisely modulating the organism’s physiological state and behavioral responses. During the cross-fostering process, sows rely primarily on olfactory cues to verify parentage; the unfamiliar scents emanating from non-biological piglets often trigger maternal rejection behaviors, manifesting as aggressive stress responses such as head-butting, biting, and driving the piglets away.

From a fundamental biological perspective, the mechanisms of pheromone-mediated mother-offspring interaction permeate the entire lactation cycle. This not only represents a survival adaptation strategy forged by animals over the course of long-term evolution but also provides critical technical targets for industrial sectors such as feed research and development and the optimization of livestock rearing practices; as such, it holds significant theoretical and practical value for enhancing production efficiency in swine farming.

Imprinting is a form of rapid, irreversible learning unique to critical periods in an animal’s life; it refers to a pivotal biological process wherein an individual, upon exposure to specific stimuli during a particular developmental stage or physiological state, forms a permanent memory that subsequently shapes its future behavior (Hudson, 1993). As a core branch of the imprinting phenomenon, olfactory imprinting describes the process by which an animal, following exposure to specific scents during a sensitive early-life phase, establishes long-term memories that continue to modulate its subsequent behavioral responses (Hudson, 1993).

Immediately after birth, a piglet’s olfactory system begins to develop, rendering it highly sensitive to the scent cues of its mother. Olfactory uniformity is critical to the success of cross-fostering piglets. The secretions from a piglet’s sebaceous glands, along with its saliva and urine—combined with the sow’s milk and vaginal secretions—collectively constitute a “parent-offspring scent system.” The pheromones within this system can be transmitted via air or direct contact, directly regulating the physiological states and behavioral responses of both the sow and the piglets; conversely, the presence of unfamiliar scents can easily trigger rejection behaviors in the sow, such as nudging, biting, or driving the piglets away.

Pheromones serve as key cues enabling piglets to locate teats and achieve effective nursing, making them vital for establishing the maternal-offspring bond. For pigs—highly social animals—early olfactory imprinting exerts a long-term influence on foraging behaviors, the establishment of social hierarchies, and the regulation of stress responses. Australian experts have confirmed through research (Campbell, 1976) that the simultaneous addition of flavoring agents to the feed of both lactating sows and nursing piglets can significantly boost the piglets’ feed intake and daily weight gain during the three weeks following weaning; compared to a control group, daily feed intake and weight gain increased by 12.2% and 24%, respectively.

**Pheromone-Mediated Imprinting Effects**

Stimulating an animal’s appetite by mimicking or enhancing scents and flavors it naturally prefers is a key strategy for increasing feed intake and improving feed utilization efficiency. Sow pheromones—particularly the volatile compounds associated with milk secretion and let-down—act as pivotal environmental signals during the early stages of piglet development. Operating through an interconnected pathway involving “neural mechanisms,” the “gut-brain axis,” and “long-term behavioral impacts,” these pheromones effectively stimulate nursing behaviors in piglets. Consequently, they influence growth rates and weaning weights, playing a critical role in boosting feed intake in weaned piglets, mitigating weaning-related stress, promoting intestinal health, and enhancing overall growth performance.

Valor Chemical has conducted an in-depth analysis of the specific pheromone components found in sows and, based on these findings, has developed a novel feed attractant: **[Fresh Milk Flavor]**. At its core, the product functions by mimicking the pheromones associated with a sow’s scent to stabilize piglet emotions, alleviate weaning stress, and stimulate feed intake. Furthermore, it incorporates pig milk-flavored components to create a synergistic effect, establishing a “mother-offspring integration” imprinting effect designed to enhance the piglets’ feed intake and overall production efficiency.em” for Early Behavioral Development in Piglets