Study location
The study was carried out at the Piggery Section of the Council for Scientific and Industrial Research - Animal Research Institute (CSIR-ARI), Katamanso, Accra. The location of the farm is in the coastal savannah zone and situated at the Adentan Metropolitan Assembly area of the Greater Accra Region of Ghana. The average relative humidity for the year is about 65% (mid-afternoon) and 95% (night time) while wind speed usually ranges between 8 and 16 km/h. The monthly temperature varies between 26 and 29oC. The highest mean monthly temperature of 29oC occurs during March and April while the lowest of 26oC is in August. The zone has a bimodal rainfall pattern with the major rainy season occurring between April and July while the minor season occurs between September and October. A short dry period separates the two periods in August. The major dry season lasts from November to February (Wallace et al. 2012).
Source of hatchery waste meal and its preparation for use as feed ingredient
Hatchery waste (HW) was obtained from the CSIR-Animal Research Institute’s Hatchery at Katamanso, and a private hatchery at Kodiabe in the Greater Accra Region, the NAT Hatchery. The hatchery waste (HW) comprised of unhatched eggs, infertile eggs, shells, dead-in-shells and low-grade unsalable chicks. The wastes were aggregated and boiled in water at 100ºC for 5 minutes and allowed to cool. The samples were then crushed to reduce the size of the particles to facilitate drying. The samples were then dried in a hot air oven, at 80oC till constant weight. The dried waste was milled to form the hatchery waste meal (HWM).
Experimental diets
Five (5) diets were formulated to contain 0%, 2.5%, 5.0%, 7.5% and 10.0% HWM. They were formulated to meet all requirements for essential nutrients in grower-finisher pig diets as recommended by NRC (1998). All the diets were formulated to be isocaloric and isonitrogenous. Table 1 shows the feed ingredients, levels of inclusion and the calculated and analyzed composition of individual nutrients in the experimental diets.
Table 1. Composition of experimental diets containing varying levels of hatchery waste meal (%) Levels of HWM inclusions in the diet
Diet
|
0% HWM
|
2.5% HWM
|
5.0% HWM
|
7.5% HWM
|
10.0% HWM
|
Fish meal
|
10.00
|
7.50
|
5.00
|
2.50
|
0.00
|
Hatchery waste meal
|
0.00
|
2.50
|
5.00
|
7.50
|
10.00
|
Maize bran
|
60.00
|
39.00
|
32.00
|
28.00
|
18.25
|
Wheat bran
|
2.25
|
14.25
|
16.25
|
18.25
|
25.00
|
Soybean meal
|
0.50
|
5.00
|
10.00
|
12.00
|
15.00
|
Palm kernel cake
|
25.50
|
30.00
|
30.00
|
30.00
|
30.00
|
Oyster shell
|
1.00
|
1.00
|
1.00
|
1.00
|
1.00
|
Salt
|
0.50
|
0.50
|
0.50
|
0.50
|
0.50
|
Premix
|
0.25
|
0.25
|
0.25
|
0.25
|
0.25
|
Total
|
100.00
|
100.00
|
100.00
|
100.00
|
100.00
|
Calculated composition % (as fed/DM)
|
|
|
|
|
|
ME (MJ/kg)
|
13.90
|
13.75
|
13.99
|
13.50
|
13.43
|
Crude protein
|
16.43
|
16.40
|
16.41
|
16.44
|
16.43
|
Ether extract
|
7.67
|
8.05
|
8.66
|
8.91
|
9.32
|
Crude fiber
|
6.80
|
6.58
|
7.81
|
8.40
|
8.37
|
Calcium
|
0.83
|
1.69
|
2.63
|
1.73
|
3.49
|
Available phosphorus
|
0.32
|
0.27
|
0.22
|
0.19
|
0.13
|
Analysed composition % (as fed/DM)
|
|
|
|
|
|
ME (Kcal/Kg)
|
12.92
|
12.77
|
12.45
|
12.41
|
12.59
|
Crude Protein
|
16.46
|
16.35
|
16.30
|
16.96
|
16.11
|
Ether extract
|
7.73
|
8.23
|
8.44
|
8.76
|
8.87
|
Crude Fibre
|
11.48
|
12.44
|
14.25
|
14.69
|
13.33
|
Ca
|
1.34
|
1.91
|
1.92
|
1.99
|
2.05
|
P (ug g)
|
5692.18
|
5903.68
|
6945.78
|
7045.14
|
7204.59
|
*Vitamin and TMP (Trace Mineral Premix): Inclusion rate is 25 kg/tonne to supply the following per tonne of feed: Vit.A,
2,000,000 IU; Vit.E, 15000 mg; Vit.B1, 1500 mg; Niacin 30,000 mg; Vit.B6, 1500 mg; Vit.D3, 4500,000 mg; Vit. K3, 3,000 mg; Pantothenic acid,12000 mg; Vit.B12, 10,000 mg; Vit. B2,6000 mg; Folic acid, 800 mg, Iron, 60,000 mg; Copper 75,00 mg; Iodine, 750 mg; Manganese, 130,000 mg; zinc, 70,000 mg; Selenium, 300mg. calcium,17.50%, Lysine,1,330 mg; Methionine, 1,075 mg; B-Corotenic acid, 350 mg.
Experimental animals
Sixty (60) crossbred Large White grower, entire male pigs (average live weight of 17.55 ± 0.1 kg) were selected from the herd at Katamanso piggery section of the CSIR-Animal Research Institute for the feeding trial.
Experimental design and dietary treatments
The 60 animals were randomly allocated in a completely randomized design (CRD) experiment to the 5 dietary treatments. Each treatment was replicated 4 times, with 3 pigs per replicate. The pigs were grouped-housed in pens partitioned with wire mesh fitted with wood. The 5 dietary treatments were designated 0% HWM (Control), 2.5% HWM, 5.0% HWM, 7.5% HWM (each and 10.0% HWM inclusion as replacement for fish meal (Table 1).
Housing and management of experimental animals
The pigs in each treatment were housed in concrete-floored, well-ventilated pens measuring 2 x 1.75 m. Each pen had both nipple drinkers and concrete water trough as well as molded galvanized plates as their feeding troughs. The walls and floors of the pens, feed and water troughs were thoroughly cleaned and disinfected (with Quincide) prior to the start of the study. The pigs were ear tagged for easy identification. The experimental pigs were fed on restricted basis, a daily quantity of feed equivalent to 5% of the individual live weight every morning. Water was provided ad libitum. The pigs were individually weighed weekly and the daily feed allocation adjusted accordingly for the following week. The pigs were fed until they attained an average market live weight of 70 ± 3 kg.
Slaughtering and dressing of pigs
Pigs were slaughtered on attaining an individual target or market live weight of 70 ± 3 kg after the weekly weighing, for the carcass quality evaluation. Eight (8) grower-finisher pigs were randomly selected from each dietary treatment, weighed on a Gascoigne weighing scale. Before slaughter, the pigs were fasted overnight but had access to water and they were slaughtered at the Meat Processing Center of the Council for Scientific and Industrial Research-Animal Research Institute (CSIR-ARI).
An electric stunner was used to stun the pigs, stuck with a sharp knife to cut the jugular vein and carotid artery and allowed to bleed for about 2 minutes. The dead pigs were scalded (100oC) immediately after bleeding and the bristle scraped off with sharp knives. The remaining hairs were singed with a blow pump flame using liquefied petroleum gas (LPG) as fuel. The carcasses were then hanged, washed and eviscerated.
Warm dressed weight was determined as the whole carcass weight after the removal of the viscera. The viscera (internal organs) were collected into a weighing container and after washing off the clots of blood and fluids, the weight was determined and recorded using a table top weighing scale1 (CAMRY Scale of 441bs x 202/20kg x 50g capacity Made in China).The liver, kidneys, heart, spleen, thymus gland and respiratory organs were separated and weighed individually, as described by (Bridi and Silva, 2007). After the removal of the visceral organs, the remaining part was designated as carcass weight. This was later expressed as a percentage of the live weight to obtain the dressing percentage. The head was removed by cutting off at the occipito-atlas joint and the feet by sawing through the hock joint at a right angle to the long axis of the leg. The warm carcass was chilled in a freezer for 24 hours at 4oC to obtain the chilled carcass weight.
The chilled carcass was divided longitudinally and the left half of the carcass was used for the carcass evaluation as described by Barca et al. (2006). The ham was separated by locating the division between the 2nd and 3rd sacral vertebrae and sawn perpendicularly along the axis of the ham. The shoulders of the carcass were separated from the loin and belly by a straight cut between the second and third ribs, and a straight cut 2.5 cm ventral to the ventral edge of the scapula. The individual parts were then weighed and recorded. The backfat depth was measured from these three points i.e., the first rib, last rib and rump. The P2 value was assessed by measuring the depth of back-fat at the P2 position (taken 6.5 cm from the dorsal mid-line and at the head of the last rib) according to the method described by Merkel et al. (1993).
Statistical analysis
All the data were subjected to analysis of variance using Genstat Discovery Edition (2016) to determine the effect of dietary treatments on the various parameters studied. Values of p < 0.05 were considered significant.