S Leeson’s research while affiliated with University of Guelph and other places

Butyric acid is the primary energy source for colonocytes, and has shown potential as an alternative to in-feed antibiotics, due to its antimicrobial activity and positive effects on production performance traits of broiler chickens. SILOhealth 104 (SILO S.P.A., Florence, Italy) is a commercial product mainly containing mono- and di-glycerides of butyrate with a small portion of propionic, caprylic, capric, and lauric acid mono- and di-glycerides. Its effects on broiler performance and carcass composition have yet to be evaluated. Four-hundred-eighty day-old male Ross 308 birds were divided into different dietary treatment groups with equal starting weights and fed a diet containing 0, 500, 1,000, 2,000, or 3,000 ppm of SILOhealth 104 for 35 days. There were no significant differences in overall average daily gain or feed: gain ratio with the addition of SILOhealth 104 to the diets (P > 0.05). At 5 wk of age, abdominal fat weight was reduced in birds supplemented with SILOhealth 104 in a dose-responsive manner (P < 0.05), while breast muscle weight increased with supplementation, with significant increases in 2,000 ppm and 3,000 ppm birds compared to controls (P < 0.05). A significant reduction in gene expression of both forkhead box protein O4 and myostatin, 2 factors that can inhibit protein synthesis, was found in the breast muscle of all SILOhealth 104 treated birds (P < 0.05). In addition, gene expression in the adipose tissue, including acetyl-CoA carboxylase alpha and lipoprotein lipase, which are associated with lipid metabolism, was significantly decreased and increased, respectively, by the supplementation of SILOhealth 104 (P < 0.05). These data suggest that the components of SILOhealth 104 can positively affect the deposition of muscle, while reducing abdominal fat deposition in broiler chickens.

Tributyrin is a butyrate glyceride, shown to have positive effects on broiler performance. This study investigated the differences in growth performance between Ross 308 and Ross 708 birds, and compared how each strain responds to tributyrin supplementation. Two-hundred-and-forty-day-old Ross 308 and 240-d-old Ross 708 chicks were divided and fed a basal diet, or diets supplemented with low or high levels of tributyrin for 35 d. Neither strain nor tributyrin supplementation had an effect on average daily gain or feed:gain (P > 0.05). All Ross 708 birds had significantly decreased relative abdominal fat weight at 3 and 5 wk of age compared with Ross 308 birds of the same treatment (P ≤ 0.05). Tributyrin supplementation only decreased relative abdominal fat weight compared with controls in Ross 708 birds at 5 wk of age (P ≤ 0.05). Ross 708 control birds had significantly higher breast muscle fat deposition than Ross 308 controls (P ≤ 0.05), and tributyrin lowered this deposition in both strains (P ≤ 0.05). Significant differences in hepatic expression of genes associated with lipid metabolism were observed between strains, and with tributyrin supplementation (P ≤ 0.05). These results support the modulation of lipid metabolism by tributyrin, and show different broiler strains responded uniquely to tributyrin supplementation.

Mixed mono- and tributyrate glycerides have been used for effective delivery of butyrate to the gut to benefit broilers. However, limited information is available on the efficacy of butyrate glycerides individually and in combination with different levels and feeding schedules. The present study has first investigated the effects of monobutyrin at inclusion levels of zero, 500, 1,000, 2,000, and 3,000 ppm on the performance of broilers, and second, the effects of its combination with tributyrin. In the monobutyrin trial, there were no overall significant differences in average daily gain or feed efficiency. However, 2,000 ppm birds had significantly decreased abdominal fat deposition compared to controls (P ≤ 0.05), and the breast muscle deposition increased in a dose-response manner to the supplementation of monobutyrin (P ≤ 0.05). The combination trial tested 5 treatment groups: control, 500 ppm tributyrin + 500 ppm monobutyrin (5T5M), 500 ppm tributyrin + 500 ppm monobutyrin staggered (5T5Ms), 500 ppm tryibutyrin + 2,000 ppm monobutyrin (5T20M), or 500 ppm tributyrin + 2,000 ppm monobutyrin staggered (5T20Ms). In staggered groups, birds were fed tributyrin for one wk followed by 2 wk of monobutyrin, after which the feed was butyrate glyceride free. The non-staggered groups had constant inclusions levels through the 5 weeks. There were no significant differences in average daily gain or feed efficiency among groups. At 5 wk of age, all treatment groups except for 5T5Ms had significantly lower relative abdominal fat weight compared to control birds (P ≤ 0.05), although 5T5Ms birds demonstrated a trend for a decrease (P = 0.095). Relative breast muscle weight was significantly increased only in 5T5M birds over control birds at 5 wk of age (P ≤ 0.05). Serum biochemistry revealed significant changes in factors relating to muscle growth and fat deposition (P ≤ 0.05). These results indicate a consistent shift in lipid metabolism with the addition of butyrate glycerides and that the deposition of breast muscle may be highest with the incorporation of butyrate glycerides at a moderate level for the duration of development.

Lutein and zeaxanthin are commonly referred to as the macular carotenoids, as they are localized to ocular tissues and their loss is associated with age-related macular degeneration. High carotenoid eggs have been suggested as a good dietary source of macular carotenoids, particularly lutein. In this paper we demonstrate two key proof of concept steps: transferring the high carotenoid phenotype to elite inbred backgrounds and carotenoid enrichment of eggs through feeding high carotenoid maize (Zea mays L.) grain to laying hens (Gallus domesticus). Using two inbred backgrounds and three high carotenoid donor lines, BC1S2 lines were developed with selections made based solely on visual assessment of kernel color. The 20-wk laying hen feeding trial consisted of four complete diets that varied for the maize component (i.e., a high-zeaxanthin maize line, a high-lutein maize line, and a conventional yellow maize line with and without a commercial lutein [Oro-glo] supplement) with eggs samples collected every 4 wk. High-carotenoid maize diet treatments yielded carotenoid concentrations in egg yolks that were approximately fourfold higher than those achieved with the conventional maize feed control and were found to be equally available to the laying hen as a lutein feed additive used as a positive control. While phenotyping by high pressure liquid chromatography (HPLC) cannot be completely eliminated, visual selection increases the proportion of high-carotenoid phenotypes and it appears that transferring the high carotenoid phenotype into elite inbred lines is relatively straightforward.

Following is invited commentary on the symposium “A Crystal Ball Look into the Future of…” delivered July 16, 2011, at the Poultry Science Association’s 100th annual meeting, St. Louis, Missouri. The symposium examined various aspects that will impact the future of poultry production over the next 10 to 20 yr. Topics included genetics, nutrition, incubation, and bird health. This paper deals with various aspects of future issues affecting global feeding and nutrition of poultry.

There will obviously be biological limits to productivity in terms of growth rate of meat birds and egg production in layers and breeding stock. We continue to see an unprecedented increase in commercial performance, and to date, we have managed to accommodate this ever-increasing potential as provided by the poultry geneticists. In many situations, we do not see the full genetic potential at the poultry farm because of myriad factors that negatively affect productivity compared with maintaining these birds under small-scale experimental conditions. Under such ideal conditions, we have realized 345 eggs in 365 d in some strains of white-egg layers, whereas handling individual broilers during trials has resulted in weights of almost 4 kg at 42 d. These values therefore represent the true genetic potential of these birds and suggest that we are nowhere near the biological limit to productivity in commercial flocks of layers, broilers, or turkeys. It is not the intent of this review to discuss the reasons for "reduced" commercial productivity; rather, the goal is to discuss potential factors that may influence the absolute biological limits to performance inherent today and, more important, in the future. 2012 J. Appl. Poult. Res. 21 : 145-148

The antimicrobial activities of n-butyric acid and its derivatives against Salmonella Typhimurium and Clostridium perfringens were studied. n-Butyric acid and its derivatives (monobutyrin and a mixture of mono-, di-, and tri-glycerides of butyric acid) were added at different concentrations (ranging from 250 to 7,000 mg/kg to a media inoculated with either Salmonella Typhimurium or C. perfringens. The antimicrobial activity of butyric acid against C. perfringens was measured at 2 bacterium concentrations and 2 inoculations involving ambient aerobic or anaerobic conditions. The most effective antimicrobial activity for Salmonella Typhimurium was observed with n-butyric acid, with 90% inhibition rate at a concentration of 1,500 mg/kg. Although minimal inhibition for Salmonella Typhimurium was observed with butyric acid glycerides, lipase addition to a mixture of mono-, di-, and triglycerides of butyric acid increased (P < 0.01) antimicrobial activity of these derivatives. Antimicrobial activity of butyric acid and its derivative against C. perfringens was higher when using a moderate initial inoculation concentration (10(5)) compared with a higher initial concentration (10(7)) of this bacterium. At a lower inoculation of C. perfringens (10(5)), >90% inhibition rate by all butyric acid glycerides was observed with prior aerobic inoculation at 2,000 mg/kg, whereas using anaerobic inoculation, only 50% monobutyrin maintained >90% inhibitory effect at 3,000 mg/kg. The antimicrobial effect of monobutyrin against C. perfringens was generally higher (P < 0.01) for 50% monobutyrin than for 100% monobutyrin. Either a mixture of butyric acid derivatives or 50% monobutyrin decreased (P < 0.01) C. perfringens in a media containing intestinal contents whereas only 50% monobutyrin decreased (P < 0.01) Salmonella Typhimurium within a media containing cecal contents from mature Leghorns. These results show that n-butyric acid and 50% monobutyrin could be used to control Salmonella Typhimurium or C. perfringens in poultry species.

It has been about 80 years since Cu was first recognized as being important for maintenance of haemoglobin. Since that time requirement values have been established and signs of deficiency and excess well documented. NRC (1994) provide the most comprehensive list of detailed requirement values for Cu for various classes of poultry, yet these lack extensive detail and are predicated on just five publications, the most recent of which was conducted 30 years ago. Requirement values average 6-8 ppm which traditionally is supplied by inorganic salts and especially copper sulphate. Other inorganic sources vary from 40-115% bioavailability of Cu compared to sulphate. Copper is easily complexed with amino acids or proteins, leading to the development of so-called organic sources of copper which are claimed to have better digestibility and/or less formation of insoluble complexes with other minerals in the digesta. Results on effectiveness of organic vs. inorganic forms of Cu are variable, although this line of research has led to appreciation of the potential to use much lower levels of supplementation. Since at least 80% of dietary copper appears in the excreta, using lower levels of diet supplementation means reduced Cu in the environment. With less supplementation, knowledge about bioavailability of Cu in major feed ingredients becomes important. Copper in cereals is reported to be 80% available to the bird while that in vegetable proteins is closer to 50% available. Availability from animal proteins is very variable, while corn distiller's grains now provides the most concentrated source of Cu within the major ingredients. Copper levels greatly in excess of requirement, at around 125 ppm, have been shown to improve performance of meat birds and egg layers. The mode of action is unknown although likely relates to antibacterial properties of Cu. Likewise high levels of diet Cu have been shown to reduce cholesterol content of eggs and poultry meat, although this is often at the expense of loss in performance and contribution of more Cu to the environment.

Ammonia emissions from poultry farms currently contribute to air pollution and acid rain. There are no regulations in North America regarding emissions of ammonia although regulations are being drawn up in the USA and there is concern about the impacts of animal agricultural on the environment. Low crude protein (CP) diets can be an effective contributor to strategies of ammonia mitigation. Since virtually all ammonia originates from nitrogenous compounds in feed, then any attempt at ammonia mitigation must involve scrutiny of the levels of nitrogen, protein and amino acids (AA). Reducing dietary nitrogen/CP leads to reduced nitrogen in the excreta with less potential for microbial conversion to ammonia. Using low CP diets may be an economical strategy for ammonia emissions since the concept involves no special feed additives other than replacement AAs. Although AA requirements for layer hens are well known, the minimal amount of CP required is less clearly defined. AA requirements should be independent of diet CP, assuming there is adequate nitrogen for protein synthesis. However, the birds' response in terms of reduced egg numbers and growth or change in egg composition, suggest that our estimates of amino acid supply are incorrect under these dietary regimes. Independent of bird age and AA supply, more problems are recorded when CP levels are < 14-15%. It is timely to redefine the maintenance AA requirements of layers. Since the composition of eggs should give us direct estimates of needs for production, the only other unknown in formulating low CP diets is the efficiency of utilisation of free amino acids versus intact proteins.