Post weaning diarrhea in pigs: risk factors and non‑colistin‑based control strategies

Post-weaning diarrhea (PWD) is one of the most serious threats for the swine industry worldwide. It is commonly associated with the proliferation of enterotoxigenic Escherichia coli in the pig intestine. Colistin, a cationic antibiotic, is widely used in swine for the oral treatment of intestinal infections caused by E. coli, and particularly of PWD. However, despite the effectiveness of this antibiotic in the treatment of PWD, several studies have reported high rates of colistin resistant E. coli in swine. Furthermore, this antibiotic is considered of very high importance in humans, being used for the treatment of infections due to multidrug-resistant (MDR) Gram-negative bacteria (GNB). Moreover, the recent discovery of the mcr-1 gene encoding for colistin resistance in Enterobacteriaceae on a conjugative stable plasmid has raised great concern about the possible loss of colistin effectiveness for the treatment of MDR-GNB in humans. Consequently, it has been proposed that the use of colistin in animal production should be considered as a last resort treatment only. Thus, to overcome the economic losses, which would result from the restriction of use of colistin, especially for prophylactic purposes in PWD control, we believe that an understanding of the factors contributing to the development of this disease and the putting in place of practical alternative strategies for the control of PWD in swine is crucial. Such alternatives should improve animal gut health and reduce economic losses in pigs without promoting bacterial resistance. The present review begins with an overview of risk factors of PWD and an update of colistin use in PWD control worldwide in terms of quantities and microbiological outcomes. Subsequently, alternative strategies to the use of colistin for the control of this disease are described and discussed. Finally, a practical approach for the control of PWD in its various phases is proposed

Effects of different dietary vitamin combinations on the egg quality and vitamin deposition in the whole egg of laying hens

The experiment was conducted to evaluate the effects of different dietary vitamin combinations on the egg quality and vitamin concentrations in the eggs of commercial laying hens. A total of 1,800 25-week-old Lohman pink-shell hens were randomly assigned to four dietary vitamin treatments as follows: NRC(1994) level, NRC (1994) level with Hy.D® (25-hydroxy-cholecalciferol), Local level (current average industry level in China) and OVN® level (optimum vitamin nutrition level), with 10 replicates per treatment and 45 layers per replicate. Hens were housed in commercial laying cages with three birds per cage and given ad libitum access to feed. Results showed the hens that received the fortified vitamin levels in the OVN® treatment had a significantly (p<0.05) lower number of cracked (.47%) and dirty eggs (.27%), and increased egg deposition of vitamin B12, folic acid, vitamin A, vitamin D, 25-OH-D3, vitamin E, vitamin B1, biotin and pantothenate (p<0.05). Treatments had no significant effect on egg-shape index, egg specific gravity, Haugh units and eggshell thickness. Hens fed the NRC-Hy.D® combination also experienced a significant decrease in cracked and dirty eggs (.70% and .44%, respectively) and an increased deposition of 25-OH-D3 in comparison with the NRC treatment. Results of the present study suggest that that the Local treatment was able to improve egg quality parameters of laying hens, but resulted in more cracked and dirty eggs. OVN® reduced the number of cracked eggs and dirty eggs, and improved the deposition of several vitamins in eggs. With the addition of Hy.D®, eggshell strength and 25-OH-D3 deposition in eggs were also improved, and cracked and dirty egg rates declined