Here is a research conducted by Chinese breeding expert.
Slatted floor is the traditional way of raising broiler chickens, which results in high concentrations of ammonia and inhalable particles in the air of the chicken house, making the chickens more prone to respiratory diseases and increasing the incidence of E. coli and coccidiosis. This leads to an increase in medication use, which can affect the safety of chicken meat. Therefore, in recent years, many domestic enterprises have gradually adopted cage or net raising to replace slatted floor, with more southern yellow feather broiler chickens being raised in three-dimensional cages.
Foreign studies have shown that net raising has no significant effect on feed conversion rate and mortality rate, and the weight is either similar to or higher than that of slatted floor, while the breast cyst and leg disease incidence are significantly higher than slatted floor. In recent years, some comparative studies have been conducted in China, which suggest that there is no difference in broiler weight and feed conversion rate between cage and slatted floor, but the mortality rate of cage-raised broilers is significantly lower. Some studies also show that the growth rate and feed return of fast-growing broilers in cage-raising are significantly higher than that of slatted floor and shed raising, and the incidence of leg disease is lower than that of shed raising, but similar to slatted floor. Other studies suggest that the weight gain of fast-growing broilers is not affected by the raising method before 5 weeks of age, but after 5 weeks, net raising results in a weight gain that is four times greater than that of slatted floor. Therefore, some researchers suggest that using brooding cages for 0-4 weeks and three-tier cages after 5 weeks results in better production performance than slatted floor.
Although previous studies have compared the impact of net raising, cage raising, and slatted floor on the production performance of broiler chickens, the high density of three-dimensional cage raising, which is currently the most widely used raising method in China and the main raising method for yellow feather broilers, has led to few comparative studies between three-dimensional cage raising and slatted floor, and it is not clear whether the effects of different raising methods on broiler chicken production are related to the season. Therefore, this study conducted two experiments to compare the production performance of broiler chickens raised on slatted floor and in three-dimensional cages in different seasons, providing guidance for better development of broiler production.
1 Materials and Methods
1.1 Experimental chickens and grouping
Experiment 1: 264 male AA broilers with similar body weights and wing numbers at 7 days old were selected.
Experiment 2: 144 male AA broilers and 144 Beijing oil chickens with similar body weights at 7 days old were divided into 2 groups according to the requirement of consistent body weight, with 6 replicates per group. The chickens were reared in cages or on slatted floors for poultry.
1.2 Experimental feed
The experimental chickens were fed with the same feed. The nutrition levels were ME 12.27 MJ/kg, CP 20.8%, Ca 0.92%, P (available) 0.45%, Lys 1.15%, Met 0.48%, and Mel+Cys 0.82% for 0-3 weeks old; and ME 12.58 MJ/kg, CP 19.1%, Ca 0.89%, P (available) 0.40%, Lys 1.0%, Met 0.42%, and Mel+Cys 0.71% for 4-6 weeks old. The feed was supplemented with 70 mg/kg of salinomycin.
1.3 Experimental methods and management
All experimental chickens were reared in the same windowed chicken house. For cage rearing, a specially designed 31-layer overlapping brooding cage (1.7m in length, 0.7m in width, and 0.45m in height) was used. For slatted floor rearing, the broiler cages were separated by nets on the cement floor, with 6 units arranged in parallel, and each unit had the same area as the cage. Sawdust was used as bedding material, with a height of more than 8cm. The rearing density was 550 cm²/chick for 2-3 weeks old, 610 cm²/chick for 4 weeks old, 680 cm²/chick for 5 weeks old, and 760 cm²/chick for 6 weeks old.
For experiment 1, the start time was at the end of June. The temperature was adjusted naturally with mechanical ventilation, and the indoor temperature for 2-6 weeks old was 32, 30, 30, 31, and 31°C, respectively. For experiment 2, the start time was at the end of March. The temperature was supplied by a coal stove with mechanical ventilation, and the indoor temperature for 2-6 weeks old was 33, 30, 22, 22, and 20°C, respectively.
The chickens were fed and watered using external hanging feeders and waterers. The waterers were cleaned once a day, and the chickens were fed twice a day. The chickens were immunized against Newcastle disease, infectious bronchitis, and Marek’s disease according to the immunization program. The chicken manure in the rearing cages was cleaned regularly. The lighting duration was 23 hours per day.
1.4 Measured parameters
The weight of each age group (individual weight for experiment 1, and group weight for experiment 2) was measured. The feed consumption and death number were recorded, and the body weight, daily weight gain, average daily feed intake, and feed conversion rate were calculated for each stage.
1.5 Statistical analysis
The experimental data were analyzed using the independent sample t-test in SPSS 10.0 software, and the results were expressed as the mean and the standard error of the mean (SEM). The percentage data were compared after Arcsin transformation.
2. Result
Table1: The effect of cage and slatted floor for poultry on the production performance of AA broilers
| Program | Weeks | Cage | Floor | SEM | P value |
| Body weight/g | 3 | 683 | 703 | 5.7 | 0.050 |
| 4 | 1031 | 1088 | 10.1 | 0.007 | |
| 5 | 1473 | 1485 | 16.6 | 0.726 | |
| 6 | 1955 | 1941 | 29.1 | 0.796 | |
| Daily gain/(g*d^-1) | 2~3 | 38.4 | 39.9 | 0.38 | 0.026 |
| 4 | 51.2 | 55.7 | 0.65 | 0.001 | |
| 5 | 64.0 | 56.4 | 1.16 | 0.001 | |
| 6 | 67.0 | 62.9 | 1.56 | 0.168 | |
| 2~6 | 51.7 | 51.3 | 0.82 | 0.820 | |
| Daily feed intake/(g*d^-1) | 2~3 | 57.9 | 59.5 | 0.84 | 0.358 |
| 4 | 92.4 | 96.4 | 1.65 | 0.022 | |
| 5 | 111.5 | 110.2 | 1.72 | 0.726 | |
| 6 | 129.7 | 125.4 | 2.59 | 0.472 | |
| 2~6 | 85.5 | 86.4 | 0.68 | 0.558 |
Table 1 shows that the feeding method has no effect on the final body weight of AA broilers in the experiment, but it does affect the body weight at different weeks and the average daily gain. The body weight of AA broilers raised in cages at 3 and 4 weeks of age was 2.8% (P=0.05) and 5.2% (P<0.01) lower than those raised on slatted floors for poultry, respectively, while their body weight at 5 and 6 weeks of age was basically the same. The average daily gain of AA broilers raised on slatted floors for poultry was 3.9% (P<0.05) and 8.8% (P<0.01) higher than that of those raised in cages at 2-3 and 4 weeks of age, respectively, while their average daily gain at 5 and 6 weeks of age was 11.9% (P<0.01) and 6.1% (P>0.05) lower than that of those raised in cages, respectively, but their overall average daily gain was basically the same. The feeding method had different effects on the feed intake of broilers at different weeks. The daily feed intake of broilers raised on slatted floors for poultry was greater than that of those raised in cages before 4 weeks of age, with significant differences (P<0.05) observed at 4 weeks of age. After 4 weeks of age, the daily feed intake of broilers raised on slatted floors for poultry was lower than that of those raised in cages (P>0.05), and there was no significant difference in feed intake throughout the experiment.
In addition, Experiment 1 also showed that different feeding methods had no significant effect on the feed conversion efficiency and overall mortality rate (results not shown) of AA broilers at different weeks and throughout the experiment (P>0.05).
Table 2: The effect of cage and slatted floor for poultry on the production performance of AA broilers and Beijing oil chicken
| Program | Weekly age | ||||||||
| Body weight/g | Cage | Floor | SEM | P Value | Cage | Floor | SEM | P Value | |
| 2 | 352 | 334 | 4.5 | 0.037 | 116 | 111 | 1.3 | 0.049 | |
| 3 | 682 | 658 | 8.4 | 0.0157 | 200 | 185 | 3.4 | 0.022 | |
| 4 | 1032 | 989 | 13.7 | 0.124 | 294 | 273 | 5.1 | 0.033 | |
| 5 | 1476 | 1449 | 21.1 | 0.519 | 406 | 374 | 5.6 | 0.000 | |
| 6 | 1992 | 1984 | 22.9 | 0.869 | 556 | 504 | 10.2 | 0.005 | |
| Daily gain/(g*d^-1) | 2 | 29.7 | 27.0 | 0.52 | 0.028 | 7.48 | 6.90 | 0.39 | 0.091 |
| 3 | 47.2 | 46.2 | 1.25 | 0.617 | 11.90 | 10.56 | 0.56 | 0.096 | |
| 4 | 49.8 | 47.2 | 1.85 | 0.489 | 13.38 | 12.57 | 0.61 | 0.551 | |
| 5 | 63.5 | 64.9 | 3.28 | 0.792 | 16.57 | 15.43 | 1.30 | 0.275 | |
| 6 | 74.0 | 76.6 | 2.70 | 0.527 | 20.18 | 18.93 | 1.68 | 0.320 | |
| Daily feed intake/(g*d^-1) | 2 | 40.8 | 38.6 | 0.65 | 0.022 | 14.6 | 13.5 | 0.17 | 0.178 |
| 3 | 77.3 | 74.4 | 0.95 | 0.274 | 23.5 | 20.6 | 0.40 | 0.003 | |
| 4 | 94.9 | 94.2 | 1.76 | 0.867 | 34.1 | 31.4 | 0.62 | 0.023 | |
| 5 | 129.5 | 134.8 | 2.45 | 0.452 | 46.7 | 39.7 | 0.50 | 0.001 | |
| 6 | 146.4 | 155.6 | 1.94 | 0.088 | 54.9 | 47.1 | 0.60 | 0.011 |
Table 2 shows that the feeding method had different effects on the body weight and average daily gain of different breeds of broilers at different weeks. The feeding method affected the growth of AA broilers, with the body weight and average daily gain of AA broilers on slatted floors for poultry being 5.1% and 9.1% lower than those in cages at 2 weeks of age (P<0.05), respectively. However, after 5 weeks of age, the average daily gain of broilers on slatted floors for poultry was higher than that in cages (P>0.05), and the final body weight was basically the same. The feeding method also affected the growth of Beijing oil chickens, with the body weight at different weeks being significantly or extremely significantly lower than that in cages for broilers on slatted floors for poultry, and the final body weight of Beijing oil chickens on slatted floors for poultry being 9.4% lower than that in cages (P<0.01). The results of daily gain comparison showed that there was a significant difference in average daily gain before 3 weeks of age (P<0.1), and the average daily gain of Beijing oil chickens on slatted floors for poultry was consistently lower than that in cages after 3 weeks of age (P>0.05).
The feeding method affects the daily feed intake of broiler chickens. At 2 weeks of age, the average daily feed intake of AA broilers is significantly lower than that of caged broilers (P<0.05), but there is no significant difference after 3 weeks of age (P>0.05). For Beijing You chickens, the average daily feed intake on a slatted floor for poultry is lower than caged broilers after 3 weeks of age (P<0.05).
Additionally, Experiment 2 also showed that different feeding methods did not significantly affect the feed conversion efficiency and mortality rate of both AA broilers and Beijing You chickens (results not shown) (P>0.05).
3. Discussion and Conclusion
Both experiments showed that cage-rearing and slatted floor for poultry had no significant effect on mortality rate and feed conversion ratio of broiler chickens, which is consistent with domestic and foreign research.
The experiment found that the feeding method had different effects on the average daily feed intake and daily weight gain of broiler chickens at each stage. By analyzing the correlation between the average daily weight gain and daily feed intake, the experiment obtained R2=0.975 (P<0.01) in experiment one, R2=0.990 (P<0.01) in AA broiler chickens, and R2=0.983 (P<0.01) in Beijing oil chickens in experiment two. This indicates that the difference in daily weight gain is caused by differences in daily feed intake. The difference in daily feed intake between different feeding methods may be related to different environmental temperatures. Experiment one was conducted in the hot summer season, and the temperature of slatted floor for poultry was lower than that of cage-rearing in the early stage, but in the later stage, the fermentation of the litter produced heat, and the ventilation effect of slatted floor for poultry was not as good as that of cage-rearing, resulting in higher environmental temperature of slatted floor for poultry than cage-rearing in the later stage. The suitable growth temperature for broiler chickens is high in the early stage and low in the later stage, that is, the temperature in the first week is about 32℃. Studies have shown that the closer the temperature is to 32℃, the more conducive it is to the growth of broiler chickens aged 0-7 days. In the later stage (4 weeks old), 22℃ is more suitable, and the higher the temperature, the lower the feed intake. Therefore, the daily feed intake of slatted floor for poultry broilers is higher than that of cage-rearing broilers in the early stage and lower in the later stage. The results also confirm the claim that cage-rearing broilers are less stressed than slatted floor for poultry broilers in summer, as suggested by Shanmuga-sundaram et al. Experiment two was conducted in the low-temperature season, and the temperature in the cage-rearing environment was higher than that on the ground, which was more in line with the needs of broiler growth and development in the early stage. Therefore, the daily feed intake of AA broilers and Beijing oil chickens in the cage-rearing group was higher than that in the slatted floor for poultry group from the age of 2 weeks. In the later stage, the high temperature in the cage-rearing group suppressed the feed intake of AA broilers without ventilation, resulting in a lower average daily feed intake of AA broilers than slatted floor for poultry broilers after 5 weeks. This indicates that the effect of feeding methods on broiler chickens is related to the season, which may also be the reason why different scholars have different conclusions on the effect of feeding methods on broiler production performance. In addition, the daily feed intake of cage-rearing Beijing oil chickens was always higher than that of slatted floor for poultry, which may be related to the fact that Beijing oil chickens (with 75% pure blood) are local chickens, which have a slow metabolism and a higher requirement for environmental temperature. Therefore, slow-growing local chickens (or improved breeds) are suitable for cage-rearing, and fast-growing large broilers can choose different feeding methods according to the season or adjust the feeding method according to the stage.
Therefore, this experiment concluded that cage-rearing and slatted floor for poultry did not affect the feed conversion rate and mortality rate of broiler chickens, but had an impact on the average daily feed intake and the carcass yield. Cage-reared chickens had a higher average daily feed intake and a lower carcass yield compared to those reared on slatted floors. However, the study also found that the use of slatted floors may increase the risk of footpad dermatitis in broiler chickens. Overall, the study suggests that both cage-rearing and slatted floors can be viable options for broiler production, but careful management practices are necessary to ensure the welfare and health of the birds.
