Adaptive response of broilers to dietary phosphorus and calcium restrictions

Abstract

The aim of this study was to evaluate the capacity of chickens to adapt to and compensate for early dietary restriction of non-phytate P ( NPP: ) and/or Ca (10 to 21 d) in a later phase (22 to 35 d), and to determine whether compensatory processes depend on the P and Ca concentrations in the finisher diet. Four diets were formulated and fed to broilers from 10 to 21 d in order to generate birds with different mineral status: L (0.6% Ca, 0.30% NPP), L (0.6% Ca, 0.45% NPP), H (1.0% Ca, 0.30% NPP), and H (1.0% Ca, 0.45% NPP). On d 22, each group was divided into three groups which received a low (L, 0.48% Ca, 0.24% NPP), moderate (M, 0.70% Ca, 0.35% NPP), or high (H, 0.90% Ca, 0.35% NPP) finisher diet until 35 d, resulting in a total of 12 treatments. Lowering the Ca level enhanced apparent ileal digestibility of P (P AID) at 21 d especially with the high NPP level (Ca × NPP, P < 0.01). The lower bone mineralization observed at 21 d in broilers fed the L diet compared to those fed the H diet had disappeared by 35 d with long-term stimulation of the P AID with the low NPP level (P < 0.001). Although P AID and growth performance were improved in birds fed the LL compared to the LH and HH treatments, tibia characteristics tended to be lower in birds fed the LL compared to those fed the LH treatment. Birds fed the HM treatment had higher P AID, growth performance and tibia ash content than those fed the HH treatment. A significant increase in the mRNA levels of several genes encoding Ca and P transporters was observed at 35 d in birds fed the L followed by the L diet compared to birds fed the L followed by the M diet. In conclusion, chickens are able to adapt to early dietary changes in P and Ca through improvement of digestive efficiency in a later phase, and the extent of the compensation in terms of growth performance and bone mineralization depends on the P and Ca levels in the subsequent diet.

Effects of dietary calcium and phosphorus deficiency and subsequent recovery on broiler chicken growth performance and bone characteristics

“…The absence of growth performance alteration when reducing dietary Ca and nPP during days 22 to 37 is in agreement with the results of Wilkinson et al (2014), Delezie et al (2015) and Rousseau et al (2016) for BW gain and feed conversion ratio. A further reduction of Ca and nPP during the finisher phase increased the deficit in bone mineralisation, from −11% on day 21 (C v. L) to −20% on day 37 (CC v. LL) based on tibia ash content.…”

“…Faridi et al (2015) showed that in the absence of phytase or vitamin D 3 , dietary nPP should be above 3.5 g/kg during the first 21 days in order to maximise tibia ash content. As dietary depletion increased, Ca and nPP relative transfer increased suggesting an increase in apparent digestibility of Ca and phosphorus in the intestine as reported by Rousseau et al (2016) in chicks fed low-phosphorus or Ca diets for 10 days. Studies have suggested that depletion appears to stimulate the expression of mRNA encoding Ca transporters CALB1, SLC8A1 and ATP2B1 and phosphorus transporters SLC20A1 and SLC34A2 (Centeno et al, 2004;Bar, 2009;Proszkowiec-Weglarz and Angel, 2013) in the intestine and the kidney.…”

“…During the finisher phase (22 to 37 days of age), Ca and nPP contents were, respectively, 0.85%, 0.57% and 0.48% and 0.35%, 0.29% and 0.24% in the C, M and L diets. The C diet contained Ca and nPP at the levels used in standard commercial conditions in Canada, whereas the L diet was based on previous studies (Yan et al, 2005;Létourneau-Montminy et al, 2010;Rousseau et al, 2016). The M diet was intermediate between the C and L diet and had the same Ca:nPP ratio as the L diet.…”

“…Grower and finisher diets were combined to form six dietary treatment sequences: CC, MM, LC, LM, ML and LL. The first treatment (CC) is the North American positive control whereas the second is the French positive control (MM) according to Létourneau-Montminy et al (2010) and Rousseau et al (2013 and2016). The third (LC) and fourth (LM) dietary sequences have been built to test depletion and repletion strategies.…”

Effects of rapeseed meal fiber content on phosphorus and calcium digestibility in growing pigs fed diets without or with microbial phytase

“…The initial pH and the buffering capacity to pH 3 were measured according to Lawlor et al (2005). Dry matter of diets, feces and digestive content of ileum and cecum, and P, Ca and TiO 2 Rapeseed fiber and mineral digestibility analysis were performed as previously explained by Rousseau et al (2016). Phytase activity was measured according to Engelen et al (1994).…”