Factors Affecting Feed Intake - What We Know_abstract

Arkansas Nutrition Conference September 2012

Factors Affecting Feed Intake – What Do We Know?

Todd J. Applegate, PhD Animal Sciences Department

Purdue University West Lafayette, IN 47907 USA

[email protected] Introduction Numerous factors have been shown to influence the birds’ feed intake, including:

a) Hygiene b) Vaccination c) Immunological response (innate vs acquired) d) Presence of microflora e) Lighting regimen (intensity, age of initiation and transition, daylight length) f) Diet phase transitions g) Prior ingredient exposure or naivety h) Feed form i) Energy density of diet j) Genetic selection k) Visual, social, and artificial cues l) Stress.

These responses, however, may vary depending on life-stage of the bird. For example early in life, Enneking (2012) documented the scientific literature associated with in feed intake behavior in hatchlings. Improvements in feed intake strategies in the literature range between feed color (green > red/yellow/blue/tan), powdered over granular and circular over angular forms, presence of maternal calls and pecking cues, absence of unfamiliar birds from social hierarchy, and some feeder movements. While our knowledge of factors affecting feed intake are plentiful, very few study and develop strategies to maximize feed intake as well as minimize factors affecting feed intake reductions/suppression. Rather than focusing on the range of all of these factors, the basis of my presentation will encompass genetic, immunological, and nutritional influencers on feed intake. Genetic Selection Several have noted the impact of selection for growth in broilers and turkeys as largely an indirect selection for individuals with a more voracious appetite. The question comes as to why (i.e. what is happening physiologically) and what consequences may be occur due to this selection. To address the “why”, Drs. Denbow and Siegel (Virginia Polytechnic Institute and State University) have spent considerable time in elucidating nervous system responses due in part to selection for feed intake. Quite simply, there are two underlying hypotheses for “why”, that they and others have put forward (Kuo et al., 2006):

1) Sympathetic nervous system activity is reduced (meaning satiety mechanisms are down regulated), or

2) Sympathetic nervous system activation occurs as a result of chronic overfeeding.


Either way, alterations to the central and peripheral nervous system are apparent. For example, we know that broilers selected for over 40 generations for growth (HWS) have altered sympathetic nervous systems, including: being more sensitive to the effects of resperine (a compound which impairs storage of biogenic amines and thus depletion of norepinephrine, dopamine, and serotonin; Kuo et al., 2006), are less responsive to the feed intake suppressing effects of alpha-melanocyte stimulating hormone (Cline et al., 2008), have altered cellular and body energy balance through kinase pathways and Compound C (Xu et al., 2011), and have continued feed intake stimulation with galanin plausibly through differences in numbers of opiod receptors (Tachibana et al., 2008). This altered sympathetic nervous system responsiveness has, therefore, led towards an increased sensitivity to stress responses having a greater effect on feed intake in growth selected birds. Thus, under chronic stress situations, it has been documented that nutrient utilization (in part due to rate of digesta passage) can be altered and thus digestibility affected (for review see Virden and Kidd, 2009). However, route of stressor can vary this response. For example, upon an immunological challenge with lipopolysaccharide (LPS), the efficiency of Lys and Thr use by the bird did not vary, whereas feed intake did (Webel et al., 1998). Immunological Costs to Feed Intake and Genetic Selection - Selection for rapid growth in broilers (Cheema et al., 2003) and turkeys (Cheema et al., 2007) has long-been criticized in reducing adaptive immunity while increasing cell-mediated and inflammatory responses. With the innate (naïve) immune response being inordinately more nutrient costly in part because of acute phase protein production and muscle catabolism, selection for growth has altered metabolic and nutrient partitioning (Ask et al., 2006) unless nutrient intake or nutritional plane is reduced (Nestor et al., 1999; Kyriazakis, 2010).

One of the biggest drivers to performance loss during an acute phase response by any animal is that of feed intake suppression. The severity, duration, and recovery of feed intake suppression due to the immunological naivety towards a particular pathogen can be influenced by pathogen load, virulence, animal genotype, and feed composition (Sandberg et al., 2006). The acute, or innate response inordinately nutrient and energy intensive. Typically, the immune system is held in a homeostatic balance between immuno-stimulation and immuno-suppression, but due in large part to the microbial content within the digestive tract, the gastro-intestinal tract (GIT) has often been described as being in under a constant, sub-clinical inflamed state.

Interestingly, the extent of feed intake suppression is not affected by nutrient density. For example, when Korver et al. (1998) changed feed energy density with substitution of cellulose with fat or starch and then challenged birds with LPS, the extent of feed intake suppression was not affected.

In some cases, the anorexia experienced during the acute phase response is necessary for some genotypes to immunologically cope with the pathogen. For example, Nestor et al. (1999) compared the response of full-fed, growth-selected (F-line) turkeys to a feed-limited, growth-selected and a random-bred line (RBC) of turkeys when challenged with a high dosage of Pasteurella multocida. Interestingly, the mortality in the full-fed, F-line turkeys was over 80% but that of the feed-limited F-line and RBC line turkeys were only 48 and 43%, respectively. Indeed, nutrient density, particularly for growth selected lines, can impart a difference in innate immune responsiveness. For example, Cheema et al. (2007), noted an increase in lymphoblastic activity when growth selected turkeys were fed 1966 representative diets vs that from 2003.


Beyond the feed intake reduction during an acute phase response, productivity is also lost due to the acute phase immune response requiring up to 10 percent of nutrient use which otherwise would have gone towards growth (Klasing et al., 2007). Other researchers have estimated this nutrient cost to be 1.3 times that of maintenance (Webel et al., 1998) or a daily cost of 0.27 g ideal protein per kg body weight (Sandberg et al., 2007). Therefore, when it comes to further work with feed additives targeted at eliciting effects in the intestine need to also consider the net effects during these sub-clinical infections, nutrient partitioning, as well as impact on feed intake behavior of the bird.

As one looks to the recent focus of research, it solely has focused on the initial response of the bird to particular challenge and/or acquired immune capacity. Largely, it has lacked the dynamics of the responsiveness required to fully grasp the productive “cost” of the response, encompassing immunological reaction, reduction and recovery of food intake, as well as restoration and healing of damaged tissue. Long-term consequences of this response have been noted on the intestine due to delayed placement after hatching (Potturi et al., 2005) or due to stressors such as early-weaning in pigs (Smith et al., 2010). Recent work from our lab also suggests that recovery from an early stressor is different between commercial broiler strains, such that partial compensatory growth is plausible in some, but not all strains (Xu et al., 2010; Figure 1).

Figure 1. Impact of lipopolysaccharide challenge (7, 9, 11, and 13 d of age) on two commercial broiler strains and their growth to 40 d of age. Notably, Strain 1 birds challenged with LPS exhibited partial compensatory growth when compared to LPS challenged birds from Strain 2 (Xu et al., 2010).


Interestingly, variation in immunological response within a genetic strain varies

extensively. For instance, Swaggerty et al. (2008) noted a 2 to 5 fold difference (lowest 5% vs. highest 5% of population) in circulating pro-inflammatory cytokines and chemokines in a commercial broiler, pure-line. Thus, the question comes as we look at the lower half of the population in terms of body weight, as we may have birds that are lighter, due likely to different reasons, namely as either “hyper- or hypo-“ responders to an innate challenge. Other factors may be influencing the variability in bird response we see within and between flocks. For example, factors such as intestinal challenges toxicological responses may influence the efficiency to which individual birds respond. Meta-analyses of swine data suggests that mycotoxicoses contributes up to 23% reductions in growth, of which only growth suppression is 15% due to changes in maintenance with the bulk of reductions (85%) attributable to inefficient use of feed (Pastorelli et al., 2012 from studies including feed contaminated with aflatoxin, deoxynivalenol, fumonisin and/or zearalenone), whereas intestinal challenges (E. Coli) results in in an 8.1% reduction in feed intake with 74% of growth suppression due to alterations in body maintenance and 26% in reductions in feed efficiency. When we think of each of these challenges, it is important to realize that they have different effective nutritional and energy requirements due to tissues and systems they effect. Additionally, due to their physiological effects, time to recovery is inordinately different, in that recovery of feed intake behavior is nearly 25% longer for intestinal challenges vs. that of mycotoxicoses (Pastorelli et al., 2012). Within intestinal insults, it is also known that there is a longer time for feed intake recovery for parasitic vs. bacterial challenges (Kyriakis, 2010).

Altering the Acute Phase Immune Response (and associated feed intake reduction) with a Multi-strain Probiotic When it comes to further work with feed additives targeted at eliciting effects in the intestine, one needs to also consider the net effects during sub-clinical infections, nutrient partitioning, as well as impact on feed intake behavior of the bird. To address this issue, we (Jiang et al., 2010) designed a 1 week experiment to examine whether dietary supplementation of a multi-strain probiotic would alleviate growth suppression and anorexia caused by lipopolysaccharide (LPS)-induced acute phase response. The experiment was designed with 4 treatments starting at 14 days of age. Prior to (0-14 days of age) and for the experiment (14-21 days of age), male broiler chicks were fed diets devoid or were supplemented with 1.7 x 108 cfu of a multi-strain probiotic /kg diet. At 14 days of age, birds fed the diet devoid of probiotic diet was further divided into 3 treatments: an unchallenged positive control (PC), (LPS) challenged negative control (LPS-NC), and pair-fed to LPS-NC. The probiotic-fed birds were also then challenged with LPS. The LPS (E. coli) was injected intra-peritoneally 4 times at 48 hour intervals at 1mg/kg body weight. The LPS challenge dramatically depressed weight gain from 14 to 21 days of age by 22% (P < 0.001). Probiotic supplementation recovered 17% of depressed growth (vs. LPS-NC; P=0.068; Figure 2). Part of the improved weight gain was due to the resurgence of feed intake of the probiotic+LPS birds occurring 48 hours earlier than the LPS-NC birds (Figure 3). Thus, the acute phase response (induced by LPS administration) diverted a large portion of consumed nutrients from tissue accretion. Probiotic supplementation lessened the duration of the anorexic effects of LPS resulting in improved weight gains versus the LPS-NC.


Figure 2. Broiler weight gain from 14 to 21 days that were injected (i.p.) with an E. coli lipopolysaccharide (LPS) at 14, 16, 18, and 20 days of age, pair-fed to the LPS treatment, fed a probiotic and injected with LPS, or an untreated control treatment (Jiang et al., 2010).

Figure 3. Broiler feed intake at 16, (2 days post-injection), 18, and 20 days of age for birds that were injected (i.p.) with an E. coli lipopolysaccharide (LPS) at 14, 16, 18, and 20 days of age, pair-fed to the LPS treatment, fed a probiotic and injected with LPS, or an untreated control treatment (Jiang et al., 2010).

“Cost” of Immunity – Acute Phase Response (feed intake)

100

125

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2 days 4 days 6 days

Days post-initial injection

Fee

d in

take

(g

/ b

ird

/ 2

day

s)

Control LPS Pair fed to LPS LPS + PoultryStar

abcP < 0.05

a

b b b

a

c c b

a

b bab

“Cost” of Immunity – Acute Phase Response (Weight gain)

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Control LPS Pair fed to LPS LPS + 5 strainprobiotic

Wei

gh

t g

ain

(g

/ b

ird

)P = 0.001

P = 0.068

Probiotic supplementation reduced the “cost” of immune response by 40%


Lighting Programs and Feed Intake Dr. Hank Classen and Karen Schwean-Lardner (Univ. Saskatchewan) recently (2010, 2012) have conducted numerous studies relating daylight length, age and severity of changes to lighting program to overall growth and carcass yield of various ages (BW) of broilers. For a more extensive summary and recommendations, please refer to their cited publications. To briefly summarize their work, however, peak performance is noted when 17 to 20 hours of daylight per day, with less of an impact (vs 23 h) when rearing birds beyond about 49 days of age. Maximization of feed intake within their studies occurred, however, when 20 hours of daylight were utilized. Additionally, transition from a 23:1 (L:D) or 24:0 (L:D) had different ramifications on feed intake as to when during the first week the transition occurred, and whether a sudden or gradual reduction in daylight length occurred.

Feed formulation/form & Feed Intake Broilers - While others have previously studied the influence of diet phase shifts, feed ingredient type, and feed form on feed intake behaviors in birds, one of the more recent groups who has published a continual series on these issues is from INRA (Tours, France). They began this work with development and validation of what they term a SRAbox (Station de Recherche Avicole) for use in feed preference and feed intake profile testing (Chagneau et al., 2006a), from which they automated feed intake results (Chagneau et al., 2006b). In this initial broiler work (Chagneau et al., 2006a), they conducted 5 minute feed preference test after a 45 minute test, which they conducted daily from 22 to 25 days of age, and again from 35 to 38 days of age. Within these tests, they attempted to elucidate preferences due to processing (steam vs cold pellet) as well as due to color (due to feed ingredient composition). Notably, they reported an order of preference for 1) all vegetable (corn:SBM:wheat) diet > 2) an 8% MBM:corn:wheat > 3) wheat based diet. Interestingly, 6 to 10 birds did not choose the wheat diet at all. When these diets were double-pelleted, the color difference was minimized, and as such the differences in preference between different diets was greatly reduced. Further work by Bourvarel et al. (2009) utilized a crossover design with broilers between 10 and 25 days of age to determine influence of prior exposure to a feed’s composition as well as energy density/pellet hardness. Notably, they reported that broilers can distinguish and actually show a preference for a higher energy density pellet independent of pellet hardness. However, this preference did not affect differences in feed intake over a longer-term (i.e. this preference was short-lived). Turkeys - In further work with turkeys (Chagneau et al., 2006b), this group attempted to look at preferences for feed form in poults from 28 to 32 days of age. Even though prior work with turkeys showed “short-term” preferences for lighter color feeds, there was no clear cut difference in feed form/formulation due the numerous confounding factors, including color, hardness of pellet, and pellet density. A follow-up study with turkey poults was reported by Lecuelle et al. in 2011, wherein they sought to determine turkey poult “color” preferences in transition from the first phase diet to the second. Their primary “take-home” message was that regardless of color, if the color of the 1st and 2nd phase diets is more similar, it reduces the feed intake drag during the first day of transition to the new diet. Green and “darker” pellets (created through food-coloring agents) did however, have a slight improvement during this transition vs. “lighter” (no food-coloring agent added). Summary

As outlined in the introduction – we have a wealth of knowledge of factors capable of short and long-term reductions in feed intake. The challenges, particularly with faster growing


strains become more susceptible to these reductions from stressors as well as a greater innate immune response make the challenge of minimizing the feed intake drag even more complicated. Therefore, I would challenge fellow researchers to pay more attention to the short-term impacts of treatments on feed intake suppression, but more importantly on the extent of feed intake reduction as well as feed intake time to recovery. References Ask, B., Decuypere, E. and van der Waaij, E.H. (2006a) Role of thyroid hormones, maternal antibodies and antibody response in the susceptibility to colibacillosis of broiler genotypes. Poult. Sci. 85, 2141-2148. Bourvarel, I., A.M. Chagneau, S. Lecuelle, P. Lescoat, G. Ferreira, C. D-Ponter, and C. Leterrier. 2009. Feed composition and hardness interact in preference and intake in chickens. Appl. Anim. Behav. Sci. 118:62-68. Chagneau, A.M., D. Bessonneau, C. Bouchot, P. Lescoat, M. Picard, and M. Lessire. 2006a.

Broiler short-term feed preferences measured with SRAbox, a new feed choice procedure. Poult. Sci. 85:808-815.

Chagneau, A.M., F. Laviron, S. Lamy, I. Bouvarel, M. Picard, M. Lessire, and P. Lescoat. 2006b. Short-term number of pecks and feed intake levels: a link with the physical characteristics of feed in four-week-old turkeys. Poult. Sci. 85:923-931. Cheema, M.A., Qureshi, M.A. and Havenstein, G.B. (2003) A comparison of the immune response of a 2001 commercial broiler with a 1957 randombred broiler strain when fed representative 1957 and 2001 broiler diets. Poult. Sci. 82, 1519-1529. Cheema, M.A., Qureshi, M.A., Havenstein, G.B., Ferket, P.R. and Nestor, K.E. (2007) A comparison of the immune response of 2003 commercial turkeys and a 1966 randombred strain when fed representative 2003 and 1966 turkey diets. Poult. Sci. 86, 241-248. Classen, H.L., K.V. Schwean-Lardner. 2012. Do lighting programs affect broiler nutrition and feeding? Multistate Poult. Nutr. Conf. Proc. Cline, M.A., W. Nandar, C. Bowden, P.P. Hein, D.M. Denbow, and P.B. Siegel. 2008. Differential feeding responses to central alpha-melanocyte stimulating hormone in genetically low and high body weight selected lines of chickens. Life Sci. 83:208-213. Enneking, S. 2012. On starve-out and early feeding behavior of commercial turkey poults. Midwest Poult. Fed. Proc. Jiang, Z., M. Mohln, G. Schatzmayr, and T.J. Applegate. 2010. Net effect of an acute phase response – partial alleviation with probiotic supplementation. Poult. Sci. 89:28-33. Klasing, K.C. 2007 Nutrition and the immune system. Brit. Poult. Sci. 48:525-537. Korver, D.R., E. Roura, and K.C. Klasing. 1998. Effect of dietary energy level and oil source on broiler performance to an inflammatory challenge. Poult. Sci. 77:1217-1227. Kyriazakis, I. (2010) Is anorexia during infection in animals affected by food composition? Anim. Feed Sci. Tech. 156, 1-9. Kuo, A.Y., J.C. Lee, G. Magnin, P.B. Siegel, D.M. Denbow. 2006. Differential autonomic nervous system response in obese and anorexic chickens. (Gallus gallus). Comp. Biochem. Physiol. Pt. B 144:359-364. Lecuelle, S., I. Bouvarel, A.M. Chagneau, F. Laviron, P. Lescoat, and C. Leterrier. 2011. Early visual experience of food does not appear to reduce subsequent feed neophobia in turkeys. Poult. Sci. 90:1-9.


Nestor, K.E., Lilburn, M.S., Saif, Y.M., Anderson, J.W., Patterson, R.A., LI, Z. and J.E. Nixon, J.E. (1999) Influence of body weight restriction in a body-weight-selected line of turkeys on response to challenge with Pasteurella multocida. Poult. Sci. 78, 1263- 1267. Pastorelli, H., van Milegen, J., Lovatto, P. and Montagne, L. (2012) Meta-analysis of feed intake and growth responses of growing pigs after a sanitary challenge. Animal 6, 952-961. Potturi, P.V., Patterson, J.A. and Applegate, T.J. (2005) The effects of delayed placement on intestinal characteristics of turkey poults. Poult. Sci. 84, 816–824. Sandberg, F.B., G.C. Emmans, and I. Kyriazakis. 2006. A model for predicting feed intake of growing animals during exposure to pathogens J. Anim. Sci. 84:1552-1566. Sandberg FB, G.C. Emmans, and I. Kyriazakis. 2007. The effects of pathogen challenges on the performance of naïve and immune animals: the problem of prediction Animal 1:67-86 Schwean-Lardner, K., and H. Classen. 2010. Lighting for broilers. Aviagen Tech. Bull. 0210-

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Smith, F., Clark, J.E., Overman, B.L., Tozel, C.C., Huang, J.H., Rivier, J.E.F., Blisklager, A.T., and Moeser, A.J. (2010) Early weaning stress impairs development of mucosal barrier function in the porcine intestine. Am. J. Physiol. Gastrointest. Liver Physiol. 298, G352-G363. Swaggerty, C.L., I.Y. Pevzner, P. Kaiser, and M.H. Kogut. 2008. Profiling pro-inflammatory cytokine and chemokine mRNA expression levels as a novel method for selection of increased innate immune responsiveness. Vet. Immunol. Immunopath. 126:35-42. Tachibana, T., M. Mori, S.I. Khan, H. Ueda, K. Sugahara, and K. Hiramatsu. 2008. Central administration of galanin stimulates feeding behavior in chicks. Comp. Biochem. Physiol. Pt. A 151:637-640. Webel, D., R.W. Johnson, and D.H. Baker. 1998. Lipopolysaccharide-induced reductions in food intake do not decrease the efficiency of lysine and threonine utilization for protein accretion in chickens. J. Nutr. 128:1760-1766. Virden, W.S. and M. T. Kidd. 2009. Physiological stress in broilers: Ramifications on nutrient digestibility and responses. J. Appl. Poult. Res. 18:338-347. Xu, L., deBeer, M., Einstein, M., Schinckel, A. and Applegate, T.J. (2010) Growth after an innate immune challenge is different between broiler strains. Poult. Sci. 89(Suppl. 1), 353-354. Xu, P., P.B. Siegel, and D.M. Denbow. 2011. AICAR and Compound C regulate food intake independently of AMP-acitvated protein kinase in lines of chickens selected for high or low body weight. Comp. Biochem. Physiol. Pt. A 159:401-412.

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Factors Affecting Feed Intake - What We Know_abstract

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