mineral availability and could potentially lead to better bone development and fewer leg problems. However, it is not known whether this is the case or whether the use of organic macro minerals has the same effect on bone development as the use of organic trace elements. Wageningen University and Research looked into this matter in an experiment fi- nanced by the Dutch Ministry of Agriculture, Nature and Food Quality, Aviagen, Darling Ingredients, ForFarmers, Hubbard, Marel Stork Poultry, Nepluvi and Nutreco.


Experiment Eggs from Ross 308 parent stock, weighing between 61.0 and 65.0 grams, were incubated at the experimental facility of Wageningen University and Research. After hatch, 864 male chicks were transported to the research facility of ForFarmers in Nijkerk. The chicks were divided into 72 pens with 12 chicks per pen. The pens were 0.90 m2


and the chicks had access to


wood shavings as bedding material. The house temperature started off at 32°C and was reduced to 22°C on day 42. The chicks were given continuous light for the first three days and then received 16 hours of light and 8 hours of darkness per day. The chicks received an IB vaccination on the day of arrival and an NCD vaccination on day 11.


Diets


All the diets were identical except for the type of macro min- erals (calcium and phosphorus) and trace elements (iron, copper, zinc, manganese and selenium). The chicks in the 72 pens were divided over four dietary treatments so that the effect of inorganic and organic raw materials could be exam- ined for both macro minerals and trace elements. These regimes were: • Inorganic macro minerals and inorganic trace elements; • Inorganic macro minerals and organic trace elements; • Organic macro minerals and inorganic trace elements, and • Organic macro minerals and organic trace elements. A three-phase feeding system was used (days 0 to 10, 11 to 28 and 28 to 42) and the four treatments were applied in each feeding phase. Chicks were fed ad lib and also had un- limited water available.


Measurements Birds were weighed at placement and on days 10, 21, 27, 34 and 42. Feed intake was also measured on the same days so that feed conversion could be calculated. Mortality was re- corded every day. On day 42, two chicks per pen were scored for footpad le- sions. These chicks were then sacrificed for necropsy and the left leg was scored for abnormalities (bacterial chondronecro- sis with osteomyelitis, epiphyseal growth plate abnormalities, epiphysiolysis and footpad lesions). The tibia was removed from the right leg and its length, thickness, volume, mineral content and mineral density were determined (see Figure 1).


How much force was needed to break these bones was then measured.


Results At day 42, the birds that were fed or- ganic macro minerals and also re- ceived organic trace elements showed a higher body weight compared to the inorganic variants (see Table 1). In ad- dition, the feed conversion over the total growth period was 5 points lower in the group of organic macro miner- als and 6 points lower in the organic trace elements group. Mortality did not differ between treat- ments. The percentage of chicks with leg abnormalities at day 42 slaughter was very small (<1%) and did not differ between treatments. The quality of the tibia bone was not influenced by the type of trace elements. However, the chicks fed organ- ic macro minerals (calcium and phosphorus) had longer and larger tibia bones with more minerals and it also took more force to break these bones (see Table 1).


Positive effects Based on this study, it can be concluded that the addition of organic macro minerals and trace elements has a positive ef- fect on the growth and feed conversion of broilers. However, the calcium and phosphorus source, in particular, also ap- pears to be important for leg bone development, with organ- ic calcium and phosphorus resulting in better development and stronger bones. With better bone development, the bird may be able to bear the rapidly increasing weight more easi- ly, resulting in fewer leg problems. The latter could not be demonstrated in this study, but this might be the case at a higher stocking density under commercial rearing conditions.


Table 1 – Effect of the macro mineral and trace element type on weight, feed intake, feed con- version and quality of the tibia of male broilers.


Macro minerals


Weight on day 0, grams Weight on day 42, grams


Feed intake day 0 – 42, grams FCR day 0 – 42 Length tibia, cm Volume tibia, cm3


Mineral amount tibia, grams Mineral density tibia, g/cm3 Breaking strength tibia, Newton


Anorganic Organic 42.6


42.6


2910b 4567 1.56a 12.5b 24.5b 14.1b 0.27b 261b


2984a 4521 1.51b 12.8a 26.1a 16.3a 0.37a 272a


a,b indicates that the treatments were demonstrably different from one another ▶ POULTRY WORLD | No. 8, 2021 13


Trace elements Anorganic 42.6


2918b 4579 1.57a 12.5 25.7 15.3 0.32 266


Organic 42.6


2977a 4508 1.51b 12.7 24.9 15.1 0.32 268


Figure1: Mineral density of the tibia bone.


PHOTO: STUDIO KASTERMANS


PHOTO: WAGENINGEN UNIVERSITY AND RESEARCH


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