Mature sows appear to be failing to reach their reproductive potential, commonly producing fewer piglets than their younger, less mature counterparts. This study demonstrated that adding betaine to the diets of pregnant older sows increased the number of piglets born, while adding folate and vitamin B12 increased the number of piglets born to younger sows and decreased early pregnancy losses. These data indicate that supplementing the diets of pregnant sows with betaine, folate and vitamin B12 can improve breeding herd efficiency and thus profitability.

Most research on ractopamine hydrochloride (RAC) satisfies the US market, which differs from its Australian counterpart in slaughter weight, dietary lysine requirements and gender. Under Australian conditions gilts fed dietary RAC require less lysine than boars in order to optimise responses in daily gain, feed conversion and carcass traits. Surprisingly a wide range of lysine : energy levels may be used for pigs supplemented with RAC, although this is dependent on RAC inclusion level and herd health.

Can fibrous diets counteract pregnancy diabetes and intake during the subsequent lactation? Pregnant gilts fed a diet high in calories had a severely reduced appetite in the ensuing lactation, causing considerable body weight loss; however, a fibrous diet at isocaloric levels did not counteract these effects. Since gilts fed less calories did not experience these effects, it seems that the amount of calories, rather than the source, determines appetite during lactation.

The energy demands of the lactating sow are often greater than her energy intake. This study showed that by increasing energy concentration of the lactation diet, sows remained in the herd and produced more piglets. Feeding sows lactation diets of 14.2 MJ DE/kg or higher will maximise productivity and help to overcome high sow turnover.

High feeding levels reduce systemic progesterone during early pregnancy; however, effects on embryo survival have been equivocal. In this study a high feeding level increased luteal tissue mass, potentially increasing progesterone output by the ovaries. This mechanism may override systemic effects of feed level and explain why a high feeding level is not detrimental to embryo survival and may even promote it.

Responses in feed efficiency and lean tissue deposition rates in Australian finisher pigs supplemented with ractopamine hydrochloride (RAC) are equivocal possibly due to insufficient lysine or RAC levels. The current recommendation of 0.56 g available lysine/MJ DE did not elicit a RAC response in growth or feed efficiency after 7 days. Dietary RAC is fed to finisher pigs for an average duration of 14 days; therefore, it is essential that diets are formulated with sufficient lysine levels to ensure the benefits of dietary RAC are captured.

Gilt progeny grow more slowly and appear to have greater susceptibility to disease than do the progeny from higher parity sows. The present study aimed to identify explanatory innate or adaptive immunity differences between gilt and sow progeny and potential pre- or post-natal influences. The results of this study suggest that gilt-born progeny may be more susceptible to disease post-weaning than sow-born progeny due to their lower birthweight and reduced humoral immune responsiveness.

Alternative feeding strategies for pigs are available which could potentially reduce feed costs. The aim of this work was to investigate the impact of three feeding strategies on growth performance and feed cost. Blend feeding or feeding a single diet have the potential to reduce feed costs in the grower-finisher period without affecting growth performance.

The use of fish oil to supplement dietary omega-3 fatty acids fed to gilts to improve gilt fertility was investigated. Although feeding supplemented diets for up to six weeks before mating had no effect on fertility, gilts fed a diet containing 3 g fish oil/kg of diet before mating and during early pregnancy had a higher embryo survival. The use of fish oil to supplement dietary long-chain omega-3 fatty acids fed to breeding gilts may be a nutritional strategy to improve first parity litter size.

Feeding the optimum level of dietary lysine is crucial to ensure lean growth is maximised and feed costs are minimised. The aim of this work was to determine the response of a major Australian genotype to increasing levels of lysine from 20 to 100 kg liveweight. Entire males and females responded to levels of lysine higher than that currently recommended for this genotype and therefore the level included in diets should be increased accordingly.

Nutraceutical feed stuffs can be used to not only meet the nutritional requirements of the pig but to support the development of the digestive and immune system. The role of spray-dried porcine plasma and yeast derived protein meal in aiding digestive and immune development in young pigs was clearly different. Understanding the mode of action and benefits of nutraceuticals beyond nutrition is necessary for their optimal use in primiparous and multiparous sow progeny.