Thesis (MPhil (Animal Sciences))--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: Over the last few decades various authors have reported the influence of day old chick quality
on integrated broiler industries. Although various methods of determining chick quality have
been reported, defining a good or a first grade day old chick can be problematic as it involves
many subjective measurements. Incubation temperature (embryo temperature) is probably
the biggest, most influential factor during incubation on chick quality. High temperatures
cause the most damage. It leads to poor growth, stress, black buttons, threads, weak chicks,
chicks with poorly erupted down that are bleached in appearance, low hatchability, late
embryonic death and early broiler mortality. This trial was designed to test whether 37.2,
37.4 or 37.5ºC was the optimum incubation temperature for hatching Hybro G+ chicks with
superior quality. The parameters that were measured were the chick length, bodyweight, and
the yolk residue of the day old chicks of the flocks set at different setter temperatures. After
hatching, 1 440 chicks (480 chicks per temperature treatment) were placed at a broiler facility
where the daily mortalities, weekly bodyweight gain and feed conversion were recorded and
calculated. The age of the breeder flock had a significant effect on all three parameters
measured in the incubation trial with p values of <0.001, <0.001 and 0.005 respectively.
There were no significant differences in chick quality parameters due to different incubation
temperatures. The age x temperature interaction could be attributed to the large influence of
the age of the breeder on egg size and consequently chick parameters. The results could be
related to the fact that bigger eggs from older breeder flocks have higher initial egg mass,
which will result in heavier embryos and thus converted to a larger day old chick. The
performance trial performed after the incubation trial showed no significant effect of the
incubation temperature on 7-day and daily mortalities, weekly bodyweight gain and feed
conversion efficiency to 42 days of life. The lack of effects observed in these trials could be
attributed to the small range of temperatures used in addition to the difficulties brought about
the use of multi-stage incubators.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/1015 |
| Date | 03 1900 |
| Creators | Du Preez, J. H. |
| Contributors | Ciacciariello, M., University of Stellenbosch. Faculty of Agrisciences. Dept. of Animal Sciences. |
| Publisher | Stellenbosch : University of Stellenbosch, Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Stellenbosch |
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