Unfed Chicks Research Articles

Circulating profile of the appetite-regulating hormone ghrelin during moult-fast and chick provisioning in southern rockhopper penguins (Eudyptes chrysocome chrysocome)

A multitude of animal species undergo prolonged fasting events at regularly occurring life history stages. During such periods of food deprivation, individuals need to suppress their appetite. The satiety signalling gut hormone ghrelin has received much attention in this context in studies looking at mammalian systems. In wild birds, however, knowledge on the ghrelin system and its role during extended fasts is still scarce. In this study, we collected plasma samples for measurements of circulating ghrelin concentrations from adult southern rockhopper penguins (Eudyptes chrysocome chrysocome) during the three to four week-long moult-fast that they repeat annually to replace their feathers. We further sampled chicks before and after feeding bouts and non-moulting adults. Circulating ghrelin levels did not differ significantly between fed and unfed chicks but chicks had significantly lower plasma ghrelin levels compared to adults. Furthermore, penguins in late moult (i.e. individuals at the end of the prolonged fasting bout) had higher ghrelin levels compared to non-moulting adults. Our results show elevated levels of circulating ghrelin during moult and generally lower levels of ghrelin in chicks than in adults regardless of feeding state. Given the scarcity or absence of knowledge on the function of ghrelin in seabirds and in fasting birds in general, our results add greatly to our understanding of the avian ghrelin system.

Relationship of Protein Synthesis to mRNA Levels in the Muscle of Chicks under Various Nutritional Conditions

The relationship between the rate of protein synthesis and the level of messenger RNA (mRNA) in the breast muscle (pectoralis major) was studied to examine the mechanisms regulating muscle protein synthesis in chicks under various nutritional conditions. The fractional synthesis rate (FSR) of protein was measured by a large-dose injection of L-[4-3H]phenylalanine. Poly(U)-Sepharose 4B affinity chromatography was used to extract Poly(A)+ RNA as mRNA. The first study examined the effect of dietary protein levels (0–60%) on protein synthesis rate and the contents of mRNA and total RNA. The fractional synthesis rate increased with increasing dietary protein levels from 0 to 20%. When chicks were fed high protein diets (40 and 60% of dietary protein), both the FSR and absolute synthesis rate (ASR) of protein were reduced compared with the 20% protein group. Multiple regression analysis indicated that for graded dietary protein levels below the dietary protein requirement, the response of muscle protein synthesis is largely regulated by variation in the ASR per unit RNA (the efficiency of RNA in synthesizing protein). At dietary protein levels above 20%, synthesis rates are also related to changes in the RNA:mRNA ratio (ribosome number relative to mRNA), the mRNA:DNA ratio (mRNA availability) and the DNA:protein ratio (DNA concentration). When chicks were food deprived for 2 d, FSR was reduced to about half that of well-fed controls. Upon refeeding of these chicks with the control diet, the FSR returned to the normal level within 0.5 h. When food-deprived chicks were refed with protein, carbohydrate or fat alone, the FSR returned to the control level within 0.5 h after consumption of each nutrient. The increase in muscle protein synthesis of unfed chicks following refeeding of various nutrients was explained by an increased ASR per unit RNA. Our results suggest that nutrient intake can change muscle protein synthesis rates in chicks largely by altering the ASR per unit RNA, in some cases associated also with changes in the levels of RNA, mRNA and DNA.

Temporal dynamics of the chicken mycobiome.

The microbiome is an integral part of chicken health and can affect immunity, nutrient utilization, and performance. The role of bacterial microbiota members in host health is relatively well established, but less attention has been paid to fungal members of the gastrointestinal tract (GIT) community. However, human studies indicate that fungi play a critical role in health. Here, we described fungal communities, or mycobiomes, in both the lumen and mucosa of the chicken ileum and cecum from hatch through 14 days of age. We also assessed the effects of delayed access to feed immediately post-hatch (PH) on mycobiome composition, as PH feed delay is commonly associated with poor health performance. Chicken mycobiomes in each of the populations were distinct and changed over time. All mycobiomes were dominated by Gibberella, but Aspergillus, Cladosporium, Sarocladium, Meyerozyma, and Penicillium were also abundant. Relative abundances of some taxa differed significantly over time. In the cecal and ileal lumens, Penicillium was present in extremely low quantities or absent during days one and two and then increased over time. Meyerozyma and Wickerhamomyces also increased over time in luminal sites. In contrast, several highly abundant unclassified fungi decreased after days one and two, highlighting the need for improved understanding of fungal gut biology. Mycobiomes from chicks fed during the first 2days PH versus those not fed during the first 2days did not significantly differ, except during days one and two. Similarities observed among mycobiomes of fed and unfed chicks at later timepoints suggest that delays in PH feeding do not have long lasting effects on mycobiome composition. Together, these results provide a foundation for future mycobiome studies, and suggest that negative health and production impacts of delayed feeding are not likely related to the development of fungal populations in the GIT.

Alterations in hepatic mitotic and cell cycle transcriptional networks during the metabolic switch in broiler chicks.

During embryonic life, chicks mainly derive energy from hepatic oxidation of yolk lipids. After hatch, chicks must rely on carbohydrate-rich feed to obtain energy. This requires an abrupt and intensive switch of metabolic processes, particularly in the liver. We recently identified a number of transcriptional and post-transcriptional regulatory networks that work concordantly to tune metabolic processes during the metabolic switch. Here, we used delayed feeding post-hatch (48h) to impede the metabolic switch in broilers. We used RNA-seq to identify hepatic transcriptome differences between late stage embryos (E18) and two-day-old chicks (D2), which were either fed-from-hatch (FED) or not fed (DLY). Between FED and E18, 2,430 genes were differentially expressed (fold-change≥ 2; FDR p-value 0.05), of these 1,237 were downregulated in FED birds and 1,193 were upregulated. Between DLY and E18, 1979 genes were differentially expressed, of these 1,043 were downregulated and 936 were upregulated in DLY birds. Between DLY and FED, 880 genes were differentially expressed, of these 543 were downregulated and 337 were upregulated in DLY birds. We found that in addition to disturbances in a number of metabolic pathways, unfed chicks had a widespread suppression of gene networks associated with cell proliferation, cell cycle progression and mitosis. Expression patterns suggest that hepatocytes of delayed-fed birds have abnormal mitosis and increased polyploidization. This suggests that post-hatch feed consumption maintains the rate and integrity of liver growth immediately, which in turn, likely helps facilitate the appropriate programming of hepatic metabolic networks.

Parent-absent calls are related to nestling reaction time and parental food allocation in the spotless starling

Absent repeat calls (ARC) are produced by nestlings of some bird species when parents are not at the nest, and play a role in sibling interactions and parental investment. We explored if individual traits influencing begging also determine ARC in the spotless starling (Sturnus unicolor), and whether this behaviour explains nestling feeding success. We video-taped natural broods and examined the effects of experimental feeding in this behaviour. Experimentally fed chicks stopped calling and received fewer feedings. Among un-fed chicks, absence calls were more frequent in smaller nestlings. We found a positive relationship between nestling reaction time to parental arrival and food acquisition: chicks that reacted first received more feedings that slower chicks. ARC performance was also positively related to reaction time: chicks that produced more calls also reacted first to parents. These results suggest that ARC may have important effects on resource allocation and family interaction networks.

Food availability affects onset of reproduction in a long-lived seabird

Life-history theory predicts that suboptimal developmental conditions may lead to faster life histories (younger age at recruitment and higher reproductive investment), but experimental testing of this prediction is still scarce in long-lived species. We report the effects of an experimental manipulation of food availability during early development and at recruitment on the onset of reproduction and reproductive performance (productivity at first breeding) in a long-lived seabird, the black-legged kittiwake Rissa tridactyla, breeding on Middleton Island, Alaska. Birds were born and raised in nests with supplemented food ('fed') or unsupplemented control nests ('unfed'), and later recruited into either fed or unfed nests. Fed chicks grew faster than unfed chicks, and males grew faster than females. Birds were more likely to reproduce at younger ages when recruiting into fed nests. Faster growth during development tended to increase age at recruitment in all individuals. Social rank of individuals also affected age at recruitment: B-chicks recruited earlier than A-chicks and singletons recruited later than A- and B-chicks. Productivity increased with the age at recruitment and growth rate as chick, but much of the variability remained unexplained. We conclude that results of this study at least partially support predictions of life-history theory: younger age at first breeding for kittiwakes that experienced suboptimal natal conditions, as well as greater productivity of early recruiting kittiwakes that grew in control nests compared with those that grew in food-supplemented nests.

Corticosterone in thin-billed prion Pachyptila belcheri chicks: diel rhythm, timing of fledging and nutritional stress

Glucocorticosteroids (GCs) of the hypothalam-pituitary-adrenal axis play a role in association with both stressful events and daily life processes. However, relatively little is known about the role of GCs in relation to daily and seasonal life processes in animals in the wild. In this paper, we present data on basal levels of plasma corticosterone CORT in chicks of a pelagic seabird, the thin-billed prion, Pachyptila belcheri, during two predictable changes in demands, the daily activity pattern and the preparation for fledging. By comparing chicks fed recently with unfed chicks, we test how GC levels are modified according to nutritional condition. In accordance with their nocturnal feeding rhythm, chicks had a clear daily rhythm with increased CORT secretion at night, but CORT levels during the active phase were also highly elevated in unfed chicks compared with fed chicks. Close to fledging, chicks rapidly increased basal CORT levels, and again unfed chicks had higher levels than fed chicks, although the age effect here was stronger than the effect of recent feeding. The present data thus support the hypothesis that GC levels are adjusted to life stages with predictable changes in demands, but food availability and/or internal energy stores also affect the level to which GCs increase.

Relationship of Protein Synthesis to mRNA Levels in the Liver of Chicks under Various Nutritional Conditions

The rate of liver protein synthesis in vivo and hepatic messenger ribonucleic acid (mRNA) levels were measured to examine the mechanisms regulating liver protein synthesis in chicks under various nutritional conditions. Fractional synthesis rate (FSR) of liver protein was measured by using a large dose injection of L-[4-3H]phenylalanine. Poly(A)+RNA was extracted as mRNA from total RNA using poly(U)-Sepharose 4B affinity chromatography. The influence of varying dietary protein levels (0–60%) on protein synthesis and mRNA concentration in the liver of chicks was examined. Both FSR (%/d) and absolute synthesis rate (ASR, mg/d) of liver protein increased with increasing dietary protein levels from 0 to 20% (the dietary protein requirement), whereas when dietary protein increased from 20 to 40%, both rates decreased significantly. This change was accounted for by changes in RNA concentration (RNA:protein ratio) and hepatic mRNA content. Second, the time course of changes in liver protein synthesis and hepatic mRNA content were measured in force-fed chicks that had been deprived of food for 2 d. Liver protein synthesis (FSR) was significantly greater 30 min after refeeding compared with that of unfed chicks. Liver protein synthesis (FSR) correlated with the activity of RNA to synthesize protein (r = 0.61, P < 0.001), and ASR was correlated with hepatic mRNA content (r = 0.37, P = 0.030). Third, experimental diets containing individual nutrients were force-fed to chicks after 2 d of food deprivation. When chicks were refed carbohydrate and protein diets, liver protein synthesis (FSR) tended to be greater by 24% (P = 0.063) and 22% (P = 0.075) at 30 min after refeeding compared with that of unfed chicks, respectively. These findings indicate that changes in the rate of liver protein synthesis in vivo due to the alteration in nutritional conditions are, at least partially, accounted for by not only RNA concentration and the activity of RNA synthesizing protein but also hepatic mRNA levels.

On the function of warning coloration: a black and yellow pattern inhibits prey-attack by naive domestic chicks

Young chicks were offered a choice of warningly coloured black and yellow and non-warningly coloured green (or olive) prey. Unfed chicks were given palatable painted mealworms on their first day. They directed their first peck at both colour types at the same probability; however, they ate the warningly coloured ones at a much lower rate. This is due to an inhibition of attack which becomes effective after pecking. Chicks which were a few days old showed the same behaviour. Since the control prey was in this case painted with an olive mixture containing the same colours as the warningly coloured mealworms, it can be concluded that the inhibition is caused by the black and yellow coloration. With accumulating positive experience of the chicks, the inhibition decreased. For permanent avoidance it must therefore be supplemented by unpleasant experience. Accordingly, chicks handled the unpalatable black and yellow ringed caterpillars of Tyria jacobaeae only a few times and always for a short period when offered repeatedly. The inhibition caused by the black and yellow pattern is attributed to a genetically fixed predisposition to avoid warningly coloured black and yellow prey which is the result of evolutionary adaptation.

Life History of Ascocotyle mcintoshi Price, 1936 (Trematoda: Heterophyidae)

The trematode utilizes the prosobranch freshwater snail, Littoridinops monroensis, in which a simple redia produces an ophthalmogymnocephalous type of cercaria, notably different from the pleurolophocercous and parapleurolophocercous cercariae reported for other species in the Ascocotyle complex. The method of infecting the fish hosts, Poecilia latipinna and Gambusia affinis, is unique in that the cercaria is ingested and penetrates through the intestinal wall to the coelom. Metacercariae produce thickwalled cysts attached to the viscera. Adults were produced within a 48 to 60-hr period by feeding metacercariae to day-old chicks. Price (1936) described Ascocotyle mcintoshi from the small intestine of the white ibis, Guara alba, from Florida. This is a report on the life history of this trematode in which the prosobranch snail, Littoridinops monroensis (Frauenfeld) (identified by Dr. F. G. Thompson, Florida State Museum, Gainesville, Florida), was found to serve as the first intermediate host and small fishes, Poecilia latipinna and Gambusia affinis holbrookii, serve as second intermediate hosts. Day-old unfed chicks were used as experimental definitive hosts. Sogandares and Lumsden (1963) reviewed the status of the Ascocotyle complex and listed 25 species which they separated into three subgenera. They retained within the genus Ascocotyle Loos, 1899, the subgenus Ascocotyle Travassos, 1930, and the subgenus Phagicola Faust, 1920. They established a new subgenus Leighia and placed in it A. mcintoshi, as the type species, and A. megalocephala Price, 1932. Since the above revision appeared, additional species have been added to the Ascocotyle complex: A. (L.) chandleri Lumsden, 1963, which becomes the third species in the subgenus Leighia, A. (A.) pachycystis Schroeder and Leigh, 1965, and A. sexidigitata Martin and Steele, 1970. Stein (1968) referred to an undescribed species of the genus which he found as metacercariae in the viscera and musculature of the fish, Cyprinodon variegatus. He was unable to obtain the adults from experimental hosts, but found a resemblance of metacercariae with adults, taken from two American mergansers, representing an undescribed species related to A. pachycystis. Received for publication 3 August 1972. Few complete life histories of species in the genus Ascocotyle complex are known. Scott (1964) reported the life history of A. (P.) diminuta (Stunkard and Haviland, 1924) Stunkard and Uzmann, 1955. SogandaresBernal and Lumsden (1963) concluded that A. diminuta is a synonym of A. angrense Travassos, 1916. Schroeder and Leigh (1965) reported the life history of A. pachycystis and Stein (1968) made many observations on the rediae, cercariae, metacercariae, and adults of A. leighi Burton, 1965, A. pachycystis, A. angrense, and A. ampullacea Miller and Harkema, 1962. Observations on metacercariaadult transformations have been made by others on several additional species. MATERIAL AND METHODS The snail host, Littoridinops monroensis, was collected in the field and reared in the laboratory in aerated tap water containing about 10% seawater. While it seemed to do well on decayed lettuce, it was routinely fed on the periphyton grown on vertical glass plates placed in aquaria exposed to sunlight. Poecilia latipinna and Gambusia affinis holbrookii used for infection were reared in the laboratory and exposed to cercariae individually in small dishes. Morphology of the larval stages was studies with the aid of a phase microscope. Redial and cercarial measurements were made on specimens fixed in hot 10% formalin. Metacercariae and adults were fixed in hot AFA solution and stained in Semichon's carmine. Measurements of these latter stages were made on mounted material. All measurements cited are given in microns. Day-old unfed chicks were infected orally by pipette and fed on either Purina Startena or a crumbled dried fish diet. The chick appears to be a satisfactory laboratory host for bringing A. mcintoshi to sexual maturity.

Regulation of lipogenesis. Stimulation of fatty acid synthesis in vivo and in vitro in the liver of the newly hatched chick.

1. A single glucose meal stimulated the incorporation of acetate into fatty acids in liver slices. If the glucose was added in vitro, it had no effect. Fructose and glycerol in vitro markedly stimulated fatty acid synthesis from acetate. Fructose and glycerol probably by-passed a rate-controlling reaction between glucose and triose phosphate. This reaction may have been stimulated by glucose administered in vivo. 2. The stimulation of fatty acid synthesis caused by fructose did not require the synthesis of enzyme, thus indicating that fatty acid-synthesizing enzymes were present in a latent form in the livers from unfed chicks.

Control of xanthine dehydrogenase in the chick pancreas

Fisher et al. (1967) have shown that pancreatic xanthine dehydrogenase in newly hatched chicks is induced by feeding whereas this enzyme in the liver, kidney, and duodenum is unaffected by the ingestion of food. This induction is due to some substance(s) in the feed and not to the nutritional balance of the diet. An extensive examination of the pancreatic system has shown that there is a 3000-fold increase in total activity between day 19 (2 days before hatching) and day 15 after hatching with chicks fed a normal diet. Unfed chicks exhibit an activity of 0.4% of maximum value and egg-fed chicks a level of 6.3%. Between the second and third weeks after hatching, specific activity in the pancreas decreases to about one-half the maximum level. When these older chicks are fasted or fed egg, activity falls and refeeding the normal diet causes a sharp increase in activity to a level double that of continuously fed chicks. These results indicate that some change occurs in pancreatic tissue slightly before hatching which allows enzyme production, and after this time activity is controlled by a dietary inducer and a “repressing effect” formed in response to the inducer.

Free Histidine in Cloacal Waste from Newly Hatched Chicks and its Relationship to Avian Lymphomatosis ,

AN INVESTIGATION of free amino acids in chickens using paper chromatography has been published by Chubb (1959). The amino acids reported in his work were found in the urine, blood and body tissues of normal birds. However, there is no information regarding free amino acids found in chickens and their relationship to avian lymphomatosis. This paper reports chromatographic investigations of the free amino acids in the cloacal waste from newly hatched unfed chicks. Throughout the investigations, all free amino acids were examined for a correlation between their occurrence and subsequent occurrence of avian lympho-matosis. It became apparent that only histidine exhibited this correlation. EXPERIMENTALSamples of cloacal waste were collected from newly hatched, unfed chicks evacuated within five hours after removal from hatching trays. The excrement was collected in individual test tubes and only the samples from female chicks were used unless otherwise noted. Ethyl alcohol was added to the…

Passerine Birds as Experimental Hosts for Posthodiplostomum minimum (Trematoda: Diplostomidae)

Posthodiplostomum minimum (MacCallum, 1921) Dubois, 1936, is a common strigeoid trematode parasitizing several species of herons. Metacercariae of this species, formerly known as Neascus van cleavei (Agersborg), occur in a wide variety of fresh-water fishes, where they invade the liver, spleen, opisthonephroi, mesenteries, and pericardium. Numerous life history studies on this species have been published, including those by Ferguson (1936, 1938, 1940, 1943), Hunter and Hunter (1940), J. H. Miller (1954), and Hoffman (1958). Several attempts to employ birds other than herons as experimental hosts for P. minimum have been reported. Ferguson (1936, 1938) and J. H. Miller (1954) showed that newly hatched, unfed chicks serve as suitable definitive hosts. Pigeons and ducklings, however, as well as chicks older than 4 days or those having been fed prior to exposure to metacercariae, remained refractory to infection, according to the latter investigator. Adults of the 14 known species of Posthodiplostomum, according to Dubois (1957), demonstrate a marked specificity for birds of the Order Ciconiiformes, particularly herons (Family Ardeidae). Dubois believes that the selective mechanisms responsible for such specificity T among avian strigeoids are related to chemical factors associated with the activity of the tribocytic organ (holdfast). That host specificity among certain avian diplostomid flukes may be somewhat less rigid than Dubois maintains was demonstrated by a series of experiments involving metacercariae of P. minimum. A preliminary report of these studies (conducted during the summers of 1959 and 1960) at the Iowa Lakeside Laboratory at Lake Okoboji) was published in 1960.