Pathology and Histology of Dietary Tryptophan Deficiency in Broiler Chicks

Abstract

The purpose of this experiment was to characterize a lesion of the rhamphotheca associated with tryptophan (TIRP) deficiency, search for other histological abnormalities,and determine whether bird size and housing conditions are contributing factors to these lesions. Day-old broiler chicks (Ross X Ross 308) were placed in either floor pens with fresh pine shavings or Petersime battery brooders with two pens of 10 chicks each per treatment. Broiler chicks from 0 to 21 days of age were fed adequate (0.24%) and deficient (0.09%) levels of TRP in diets based on corn, corn gluten meal, and gelatin. Separate groups of control chicks were pair fed daily with the deficient chicks. Deficient chicks grew less efficiently than did the pair-fed controls. Upon gross examination, a lesion of the maxillary rhamphotheca in the vicinity of the nares was observed in 61% of TRP-deficient birds housed in the battery and 13% of the birds housed in floor pens. A similar gross lesion was only observed in one control bird. These lesions were located along the upper portion of the beak between the nares and appeared as a crusty or scab-like area on gross examination, composed of detritus, heterophils, and plasma protein. Inflammation occasionally was observed at the dermoepidermal junction. The incidence of lesions was reduced in floor pens compared to battery brooders, but similarly sized birds did not exhibit the lesion. The number of lesions seen grossly and histologically in TRP-deficient birds, as compared to control birds, supports the hypothesis that TRP deficiency is the primary cause of these lesions around the nares of broilers. Secondary environmental factors, perhaps coprophagy, also influence the incidence of the lesion.

Microanatomy of passerine hard‐cornified tissues: Beak and claw structure of the black‐capped chickadee (Poecile atricapillus)

“…Basic staining of avian beaks with hematoxylin and eosin demonstrated most major structures in the chickadee beaks and claws we examined and has been reported by others to reveal histopathological changes associated with certain disease conditions (Kingsbury et al,1953; Lucas and Stettenheim,1972; Homberger and Brush,1986; Gentle et al,1995; O'Toole and Raisbeck,1997; Monroe et al,2003). However, we also found that special stains greatly improved our ability to distinguish specific features of interest.…”

“…We used paraffin as the embedding medium, which allowed for sectioning with a regular microtome and generally worked well for beak and claw tissue in this and other reported studies, but alternative methods should also be considered (Lucas and Stettenheim,1972; Gentle et al,1995; Monroe et al,2003). When resectioning blocks that had been cut previously and stored for up to 1 year, we encountered increased fracturing of hard‐cornified tissues, resulting in poorer sections.…”

“…Beaks and other cornified epidermal tissues feature prominently in a number of common avian diseases caused by nutritional, viral, parasitic, and toxic agents (Pass and Perry,1984; O'Toole and Raisbeck,1997; Monroe et al,2003; Olsen,2003; Schmidt et al,2003; Fletcher and Abdul‐Aziz,2008). We recently documented an epizootic of beak deformities of unknown etiology among wild bird species in Alaska and the Pacific Northwest region of North America (Handel et al,2010; VanHemert and Handel,2010).…”

The integration of digestion and osmoregulation in the avian gut

“…Coates, Ford & Harrison, 1968; Klasing, 1998). For example, Klasing (1998) states that deficiencies for several vitamins may easily be induced in poultry when husbandry conditions prevent coprophagy, but rarely occur when they have access to their faeces (see also Monroe et al , 2003). The plausibility of vitamin nutrition via coprophagy is arguably balanced by questions about whether behaviour of domesticated species at high stocking densities is a good model for wild herbivores.…”

Clinicochemical follow-up of broiler rearing — A five-week study

“…Moreover, not only the occurrence of myopathies but also an improved sensitivity towards triggering factors is reported [e.g. heat stress (Sandercock et al, 2001), dietary deficiencies (Monroe et al, 2003) or malnutrition (Mozdziak et al, 2002)]. …”