Newly weaned pig encounters psychosocial, physical, and nutritional stressors simultaneously when their immune system is not fully developed. These stressors have a cumulative effect on the immune response that contributes to the post-weaning growth lag which is characterized by depression in feed intake, reduced or negative growth rates, and increased susceptibility to pathogens in the first 24 to 48 h post-weaning. Consequently, the intestinal integrity, and digestive and absorptive capacity are impaired, and there is an increase in intestinal oxidative stress. It also causes the shifts in the taxonomic and functional properties of intestinal microbiome abruptly, thereby adversely affecting the health and performance of animals. It has been suggested that the effects of weaning stress on immune functions, intestinal barrier functions, and nervous system function in early weaned pigs extends into adulthood. The inclusion of different types of feed additives into the diet have been reported to alleviate the negative effects of weaning stress. The objective of this paper was to provide an overview on how the weaning stress affects gut health and the impact it has on production efficiencies, as well as the mechanistic aspects of several feed additives applied in reducing the weaning associated gut health problems and performance inefficiencies.

Vitamins and minerals categorized as micronutrients are the essential components of animal feed for maintaining health and improving immunity. Micronutrients are important bioactive molecules and cofactors of enzymes as well. Besides being cofactors for enzymes, some vitamins such as the fat-soluble vitamins, vitamin A and D have been shown to exhibit hormone-like functions. Although they are required in small amount, they play an influential role in the proper functioning of a number of enzymes which are involved in many metabolic, biochemical and physiological processes that contribute to growth, production and health. Micronutrients can potentially have a positive impact on bone health, preventing bone loss and fractures, decreasing bone resorption and increasing bone formation. Thus, micronutrients must be provided to livestock in optimal concentrations and according to requirements that change during the rapid growth and development of the animal and the production cycle. The supply of nutrients to the animal body not only depends on the amount of the nutrient in a food, but also on its bioavailability. The bioavailability of these micronutrients is affected by several factors. Therefore, several technologies such as nanoparticle, encapsulation, and chelation have been developed to improve the bioavailability of micronutrients associated with bone health. The intention of this review is to provide an updated overview of the importance of micronutrients on bone health and methods applied to improve their bioavailability.

Objective: This experiment investigated the effects of supplementing vitamin D3-fortified sow and progeny diets with 25(OH)D3 on growth performance, carcass characteristics, immunity, and pork meat quality.Methods: The present study involved the assessment of supplementing the diet of sows and their progeny with or without 25 (OH)D3 in a 2×2 factorial arrangement on the performance and production characteristics of wean-finish pigs. Forty-eight multiparous sows were assigned to a basal diet containing 2000 IU/kg vitamin D3 and supplemented without (CON) or with (TRT) 50 μg/kg 25 (OH)D3. At weaning, a total of 80 pigs each from CON and TRT sows were allocated to weaning and growing-finishing basal diets fortified with 2,500 and 1,750 IU/kg vitamin D3 respectively and supplemented without or with 50 μg/kg 25(OH)D3.Results: Sows fed 25(OH)D3-supplemented diets improved pre-weaning growth rate of nursing piglets. A significant sow and pig weaning diet effect was observed for growth rate and feed efficiency (p<0.05) during days 1 to 42 post-weaning. Pigs consuming 25(OH)D3-supplemented diets gained weight faster (p = 0.016), ate more (p = 0.044) and tended to convert feed to gain more efficiently (p = 0.088) than those fed CON diet between days 98 and 140 post-weaning. Supplemental 25(OH)D3 improved water holding capacity and reduced drip loss of pork meat, increased serum 25(OH)D3 level, produced higher interleukin-1 and lower interleukin-6 concentrations in blood circulation, downregulated myostatin (MSTN) and upregulated myogenic differentiation (MYOD) and myogenic factor 5 (MYF5) gene expressions (p<0.05).Conclusion: Supplementing vitamin D3-fortified sow and wean-finish pig diets with 50 μg/kg 25(OH)D3 significantly improved production performance suggesting their current dietary vitamin D3 levels are insufficient. In fulfilling the total need for vitamin D, it is strongly recommended to add 50 μg/kg 25(OH)D3 “on top” to practical vitamin D3-fortified sow and wean-finish pig diets deployed under commercial conditions.

This study was conducted to evaluate the supplementation of glutamic acid (Glu) to reduced protein diets on the performance of weanling pigs. One hundred and eighty crossbred weanling pigs ([Yorkshire × Landrace] × Duroc, 21 d old) having similar body weight (BW) of 6.45 kg were randomly allotted to 1 of 6 dietary treatments (5 pigs per pen [2 barrows and 3 gilts]; 6 pens per treatment) based on BW and sex during a 6-week trial. Dietary treatments consisted of positive control (PC) diet formulated to have 226.9, 205.6, and 188.8 g crude protein (CP) during phases 1, 2, and 3, respectively, and negative control (NC) diets with 20 g CP reduction from PC diets and addition of Glu with increasing levels, resulting in the calculated Lys-to-Glu ratios of 1:2.25, 1:2.30.1:2.35, 1:2.40, and 1:2.45, designated as NC, NC1, NC2, NC3, and NC4, respectively. The BW of pigs receiving PC diet was higher (P < 0.05) than those receiving NC diet at d 7, 21 and 42. A higher (P < 0.05) average daily gain (ADG) from d 1 to 7, 8 to 21, 22 to 42 and during the overall experiment period was observed in pigs fed PC than NC diet. Pigs fed NC diets including the graded level of Glu linearly increased (P < 0.05) BW at d 42, ADG and gain-to-feed ratio (G:F) during the overall experimental period. In addition, trends in linear increase in BW (P = 0.056) at d 7 and ADG from d 1 to 7 and d 22 to 42 (linear effect, P = 0.081, P = 0.058 respectively) were observed. A tendency in the linear increment of NH₃ (P = 0.082) at d 21 and linear reduction in methyl mercaptans (P = 0.054) emission at d 42 was observed in pigs fed NC diets supplemented with graded level of Glu. In conclusion, supplementing the reduced protein diet with Glu enhanced the growth performance in weanling pigs suggesting that supplementation of Glu can compensate the reduction of 2% CP in the basal diets.