Journal of Animal and Feed Sciences, 23, 2014, 64–72 The Kielanowski Institute of Animal Physiology and Nutrition, PAS, Jabłonna Feeding broiler chickens with practical diets containing lupin seeds (L. angustifolius or L. luteus): effects of incorporation level and mannanase supplementation on growth performance, digesta viscosity, microbial fermentation and gut morphology S.Smulikowska 1 , P. Konieczka, J. Czerwinski, A. Mieczkowska and J. Jankowiak The Kielanowski Institute of Animal Physiology and Nutrition, PAS, 05-110 Jablonna, Poland KEYWORDS: Lupinus angustifolius, Lupinus luteus, ileal viscosity, gut morphology, broilers Received: 16 October 2013 Revised: 17 January 2014 Accepted: 4 March 2014 1 Corresponding author: e-mail: s.smulikowska@ifzz.pan.pl Introduction Only two species of sweet lupin are being culti- vated in Poland in recent years – narrow-leafed lupin (L. angustifolius), which is sometimes referred to as blue lupin, and yellow lupin (L. luteus), as these spe- cies are more anthracnose-resistant than white lupin (L. albus). The supply of lupin seeds in Poland re- cently increased, but there are no recommendations as to the safe level of these seeds in poultry diets. The main drawback of lupin in the past was its high alkaloids content. In yellow lupin harvested in the years 1991–1994 and analysed by Wasilewko and Buraczewska (1999), the alkaloids content was from 230 to 1300 mg · kg –1 (lupinine, gramine and spar- teine); in narrow-leafed lupin it ranged from 300 to 440 mg · kg –1 (lupanine and 13-hydroxylupanine). Seeds of new Polish cultivars of sweet lupins with ABSTRACT. Total 208 day-old female broilers were fed on isonitrogenous and isoenergetic diets containing seeds of sweet narrow-leafed (L. angustifolius cv. Bojar – NL) or sweet yellow (L. luteus cv. Parys – YL) lupin at the level of 0 (control, C), 10% (days 1–14), and 15% or 25% (days 15–35 of life). The diets were fed unsupplemented or supplemented with mannanase. At the end of second week of life, the birds fed both lupin diets were smaller than control birds, due to lower feed intake (P < 0.05). The inal body weight (P < 0.05) and body weight gain (P < 0.01) in birds fed the NL were higher than in those fed the YL diets due to higher (P < 0.01) feed intake, but their feed conversion ratio was worse (P < 0.01). The higher dietary lupin level did not affect feed intake, but depressed feed utilization. The relative liver weight was greater in birds fed YL than NL. The viscosity of ileal digesta in birds fed the NL diets averaged 3.12 mPas.s and was signiicantly greater than in control and YL-fed birds. Villi height and crypt depth were lower (P < 0.05) at the increased level of di- etary lupin. The dietary treatments did not affect the total short-chain fatty acid concentration in ileal and caecal digesta. Mannanase supplementation did not signiicantly affect any of the measured parameters, but increased the butyrate concentration in caecal digesta (P < 0.05). Inclusion of sweet lupin at a 15% level can be accepted in older broiler diets provided with adequate amino acid and fat supplementation.