Abstract

Nutrition of weanling pigs remains a key topic of interest in pig production because a good start in the post-weaning period is critical in the subsequent growth, development and survival of pigs through to market. The overriding aim of nutritional programmes is to transition pigs from relatively high-cost diets eaten in smaller quantities to less expensive diets that weaner pigs consume in greater quantities, without detriment to the health and welfare of the animals. Nutritional programmes for weanling pigs are still largely based on the inclusion of antimicrobial compounds such as antibiotics and ZnO, however there is some recognition, even in countries where these compounds are still permitted for use, that sentiment is changing and there is a need to search for other products/strategies to enable pigs to handle the post-weaning period.

Introduction

The types of feeding programmes for weanling pigs differ around the world, and the nature of these programmes predominately reflect differences in ingredient price/availability (hence diet cost), management considerations (eg. age at weaning), and the general nature of the production system (eg. restrictions on use of antimicrobials in the diet). A plethora of papers, reviews and articles have been written concerning the nutrition of newly weaned pigs, and it is not my intention to reiterate this information. There is no doubt, however, that diet formulation and ingredient selection are critical factors in the successful implementation of nursery feeding programmes, although the age and weight of pigs at weaning are major determinants of performance in the first four weeks following weaning and subsequently through to slaughter (discussed by Dritz, 2004). Similarly, the design of any feeding programme for weaner pigs needs to consider the physiological development (or underdevelopment) of the gastrointestinal tract and interactions with the resident microbiota (Pluske et al., 2004), because the processes of digestion and absorption along with microbial digestion of feed components play key roles in meeting the maintenance requirement of the newly-weaned pig and contributing to growth and, in some circumstances, the gastrointestinal health of the pig. This paper explores some alternative approaches to post-weaning nutrition.

Basis of Nutrient Specifications for Weaner Pigs

Tokach et al. (2003) listed the three major concepts when formulating diets for newly weaned pigs as:

• Adjusting pigs to the simplest and relatively lowest cost diets as quickly as possible after weaning,
  
• Maximizing feed intake to ensure that the pig consumes sufficient energy and nutrients at a time when excess mobilization of body reserves (primarily lipid) can occur, and
  
• Formulating the initial diets with highly digestible ingredients that complement the pattern of digestive enzymes, and digestive enzyme development, in the gastrointestinal tract.

Therefore, weanling pig diets have been manipulated predominately to overcome the limitations or immaturity in digestive function so as to maximize the growth of the whole animal. As such, ingredient selection (in addition to cost) to meet these objectives is generally based on nutrient digestibility, amino acid density, lactose concentration, and stimulatory effects on voluntary feed intake from products such as spray-dried animal plasma. The NRC(1998), for example, list the nutrient requirements for pigs of different weights and, as has been described previously in many other papers, nutrient requirements per kg of diet (eg. lysine) and the diet complexity generally decrease with age in accordance with increased feed intake by the pigs. Inherent to changes in diet specifications after weaning is an understanding of the gastrointestinal changes that occur, and this will now be discussed.

Further Information

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