Tackling the future challenges of Organic Animal Husbandry - vTI

RAHMANN G & GODINHO D (Ed.) (2012): Tackling the Future Challenges of Organic Animal Husbandry.
Proceedings of the 2 nd OAHC, Hamburg/Trenthorst, Germany, Sep 12-14, 2012
activity of laying pullets reared in the tropics. One hundred and twenty Black Nera ® birds (20 wk
of age), housed in a four replicate groups of 30 birds in four free –range cabins providing
0.5m 2 /bird with free access to organic grass paddock at stocking density of 5m 2 /bird. Similarly,
120 birds (of the same strain and age) were housed in a conventional battery cages. The battery
cages were commercial wire cages containing 6 birds per cage, providing 645 cm 2 of floor space
per chicken and also divided into four replicate groups of 30 birds each. The birds were randomly
selected from a bank of deep litter pen, to ensure uniformity. Birds were fed organic laying chicken
diet that contained no synthetic methionine according to EC Regulation 1804/99. The diet was a
standard organic ration which is known to support good performance and it contained in 900grams
per kilogram dry matter basis: ground white maize, 310; maize offal, 125; rice bran, 100; full fat
soyabean ,210; fishmeal, 70; limestone, 71; dicalcium phosphate, 9; vitamin-mineral premix (Roche
Nutripol 5 ® ), 2.5 and salt, 2.5. The diet contained per kilogram: ME 11.62MJ, 162g crude protein,
8g lysine, 6g methionine + cystine,4g methione, 61g ash, 36.9g Ca and 4.20g non phytate P.
Birds in each replicate group were weighed together at beginning of the experiment and 30 weeks
in lay respectively. Known quantities of organic feed were supplied to each replicate group at the
beginning of each week and the left-over at the end of the 7 day period was subtracted from the
amount supplied to obtain the feed consumed by the replicate group. Cumulative feed intake was
the summation of the feed consumed within a particular time of reference. Feed intake per bird was
determined by dividing the cumulative feed intake by the total number of birds that consumed the
quantity. feed conversion efficiency was determined by calculating:
(a) Feed per dozen egg (kg/dozen eggs) = Amount of feed consumed x 12
Total number of eggs
Eggs were collected once daily, at 15.00 GMT. Records of daily egg production were kept throughout
the period of experimentation on a replicate basis which were summed up weekly. Weekly egg
production figure per replicate were pooled and expressed as percentage Hen- day egg production at
expiration of the experiment. Hen day egg production was calculated as the percentage of the ratio
of number of eggs laid to the number of hen days. It was derived by the formulae:
Hen- day egg production (%) = Number of eggs laid x 100
No of hen days
Number of hen days = Number of days in lay x number of birds
Behavioral observation was started at 8:00 am by scan sampling (Altumann, 1974), where the birds
were scanned for 10 minutes with at 1 minute interval. The same observations were recorded at
2:00 pm to avoid the effect of diurnal rhythm (El-Lethey et al., 2001), thus a total of 20 minutes/
cage or free-range / day, twice per 2weeks. Evidence of feather loss over the whole body was
done biweekly for 20 birds per replicate randomly throughout experimental period and scored as
minimal, slight or severe (1 to 3). Visual assessments of feather loss of head/neck area
and back/vent areas of the pullets were scored on a scale of 1 to 3, following modification to the
system reported by Sikur et al.(2004).
A feather score of 1 indicated No/Minimal feather loss (No bare skin visible, no or slight wear, only
single feathers missing ); a score of 2 indicated Slight feather loss (Moderate wear, damaged
feathers or 2 or more adjacent feathers missing up to bare skin visible < 5cm maximum dimension)
; and a score of 3 described Severe feather loss (Bare skin visible ≥ 5cm maximum dimension). The
feather loss for each replicate group bird was calculated by adding over all score for each area divi-
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