Research Article

Effects of Housing and Feeding Types on Growth and Physiological Performance of Growing Rabbits (Oryctolagus cuniculus) in Humid Tropics

Mathew O. Ayoola1*, Kayode Sasona1, Oluwakamisi F Akinmoladun2, Tolulope O. Faniyi3, Abel O. Oguntunji1, Tunde E. Lawal1

1Animal Science and Fisheries Management Unit College of Agriculture Engineering and Science Bowen University, P.M.B. 284, Iwo, Osun State Nigeria; 2Department of Animal and Environmental Biology, Faculty of Science, Adekunle Ajasin University, PMB 001 Akungba-Akoko, Ondo-State, Nigeria; 3Department of Animal Science, Faculty of Agriculture, Ajayi Crowther University, Oyo, Oyo State.

Received | September 05, 2023; Accepted | November 28, 2023; Published | January 26, 2024

*Correspondence | Mathew O. Ayoola, Animal Science and Fisheries Management Unit College of Agriculture Engineering and Science Bowen University, P.M.B. 284, Iwo, Osun State Nigeria; Email: mathew.ayoola@bowen.edu.ng

Citation | Ayoola MO, Sasona K, Akinmoladun OF, Faniyi TO, Oguntunji AO, Lawal TE (2024). Effects of housing and feeding types on growth and physiological performance of growing rabbits (Oryctolagus cuniculus) in humid tropics. Adv. Anim. Vet. Sci., 12(2):327-336.

DOI | https://dx.doi.org/10.17582/journal.aavs/2024/12.2.327.336

ISSN (Online) | 2307-8316

Copyright: 2024 by the authors. Licensee ResearchersLinks Ltd, England, UK.

This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

Introduction

Over the years, farmed rabbit (Oryctolagus cuniculus) production has gained popularity and proven to be a viable means of increasing animal protein sources (Akinmoladun et al., 2018). Apart from the nutritional attributes of its meat (rich in protein, low in cholesterol and fat), the rabbit has a high growth rate, produces large litters with short generation intervals, and can subsist on forage, unlike other livestock (Prajapati et al., 2019). 

In most developing countries, the high feed costs and scarcity of quality feed and fodders constitute a significant constraint to livestock production (Nworgu et al., 2000; Alabi et al., 2017). Being primarily herbivores and hindgut fermenters, rabbits could effectively utilize quality fodders exclusively or combined with concentrates (Bhatt et al., 2009). Studies evaluating rabbit management with forages and compounded concentrates/supplements have been well explored. However, rabbits reared solely on forages (Bamikole and Ezenwa, 1999) or compounded concentrates (Khuc and Preston, 2006) do not give optimum results in the tropics.

The type of housing environment adopted should provide a sufficient allowance for growing rabbits to stretch and move at all age intervals (Onbasilar et al., 2005). Rabbits can be reared in cages or pens (deep litter), either individually or in a grouped housing system, and each comes with its own merits and demerits. In addition to the restricted movement space that cages cause, studies have shown that housing rabbits in cages causes stress, reduces feed intake and weight gain, and increases the likelihood of aggressive lesions on the body (Szendro and Dalle-Zotte, 2011). On the other side, the pen floor gives the animal constant, direct contact with the floor (locomotive and resting behaviour) and, when adequately bedded, provides a warm lying area for rabbits, thereby minimizing the influence of environmental temperatures (Matics et al., 2014; Prajapati et al., 2019). Despite the advantage of deep litter, studies have shown that rabbits can consume litter materials, thus predisposing them to an increased risk of digestive diseases and mortality (Dal Bosco et al., 2002). Rabbits found to have consumed litter materials show reduced weight gain, body weight and dress-out percentage due to reduced feed consumption (Combes et al., 2010). Ayoola et al. (2020) affirmed that the improvement of reproductive patterns in rabbits should correspond to welfare concerning housing and feeding for profit maximization. 

The effect of housing systems on rabbits’ growth, welfare and reproductive characteristics have been well documented (Ndor et al., 2010; Krunt et al., 2020). There are factors in the blood whose levels are usually determined to assess the degree of well-being of animals as deviation in these factors is used to assess nutritional stress or other factors that predispose animals to stress (Ayoola et al., 2023). The commonest parameter for measuring these implications is through the blood serum biochemistry of the animals (Aro et al., 2013). Haematological studies are important because the blood is the major transport system of the body, and an evaluation of the haematological profile usually furnishes vital information on the body’s response to injury of all forms, including toxic injury (Ihedioha et al., 2004). Moreover, the comparison of blood profile with nutrient intake might indicate the need for adjustment of certain nutrients upward or downward for rabbits (Rafiu et al., 2013).

Hypothetically, a combination of an appropriate housing and feeding system will significantly improve the productivity and welfare of rabbits. Experiments that assessed the combined effect of feeding and housing systems on rabbits are sparse. Hence, this study assesses rabbits’ growth and health status under three housing and feeding systems.

Materials and Methods

Study area and ethical clearance

The research was conducted at the Teaching and Research Farm, Bowen University, Iwo Osun State, Nigeria. The experimental site lies approximately on latitude 4.1770° E and longitude 7.6401° N with an average temperature of 28.4oC and average precipitation (rainfall) rate of 206.63mm. The methods/procedures used in this study were concomitant with those outlined in the Animals ARRIVE guidelines and were carried out by the U.K. Animals (Scientific Procedures) Act, 1986 and associated guidelines; EU Directive 2010/63/EU for animal experiments; or the National Institutes of Health guide for the care and use of laboratory animals (NIH Publications No. 8023, revised 1978). The study was conducted with the approval of the Bowen University Ethics Committee.

Experimental animals, design and management

Ninety (90) unsexed New Zealand White rabbits (average weight: 0.92±0.01 kg) of 60 days old were allotted to the three housing systems and three feeding systems in a 3x3 factorial experiment in a completely randomized design. The treatment groups were three housing systems (concrete pen with litter filled floor (H1), concrete pen with soil filled floor (H2) and battery cage (H3) and three feeding systems (forage only (F1), concentrate only (F2), and forage+concentrate (F3). Rabbits were fed ad libitum throughout the trial period that lasted 10 weeks, and the forage+concentrate combination was offered as a total mixed ration (concentrate in the morning, and forage at evening). The animals were housed in a nine (9) housing and diet combination groups (dietary forage (Tridax procumbens), compounded feed alone or both) with five (5) animals per treatment. Each treatment was replicated twice, and water was administered ad libitum. The dimension of each cage was 1.025x0.525 m, basic area 0.54 m2 and five rabbits were housed per cage). The concrete pen with litter filled floor was constructed using concrete and spread with litter floor material of wood shaving at 5cm thickness. The concrete floor filled with soil was made of concrete and filled with sand at 30cm thickness. Each rabbit was provided (1.35 x 0.925) 1.2 m2) of floor space and standard routine management throughout the experimental trial. The rabbits were acclimatized for one week in their respective treatment groups before the commencement of the trial. In this study, pens and cages were kept under the same micro-environment (Temperature 25.00±0.61oC and relative humidity 65.00±3.38%) where a continuous 16L: 8D lightning schedule was applied throughout the experiment. The simulated floor was stirred and disinfected every two weeks with antimicrobial/fungicide (Polidine (Iodophor), and the cages, feeder, and water trough were regularly cleaned. The litters and soil bedding was changed twice during the 10 weeks trial. The concentrate diet was formulated to satisfy the nutritional needs of growing rabbits. Table 1 lists the components and nutrient makeup of concentrate and forage diets.

 

Table 1: Ingredients, nutrient compositions of concentrate (g/kg) diets.

Ingredient	% Inclusions	Forage (T. procumbens)
Maize	49.3	-
Wheat offal	16.0	-
Groundnut cake	12.5	-
Soyabean meal	14.5	-
Oyster shell	1.0	-
Bone meal	2.0	-
Premix*	2.5	-
Salt	2.0	-
Methionine	0.1	-
Lysine	0.1	-
Total	100	-
Calculated values
Metabolizable energy (Kcal/kg)	2800.5	-
Moisture	8.35	14.10
Crude protein (%)	20.1	16.01
Crude fibre (%)	4.98	10.52
Ether extract (%)	5.5	3.05
Ash	7.25	12.55
Nitrogen free extract	65.12	25.16

 

*Premix to provide the following per kg of feed: Vitamin A-500 IU, Vit. D3 - 1,200 mg, Vit. E - 11 mg, Vit. K3 - 2 mg, Riboflavin - 20 mg, Nicotinic acid -10 mg, Pantothenic acid - 7 mg, Cobalamin - 0.08 mg, Choline chloride - 900 mg, Folic acid - 1.5 mg, Biotin - 1.5 mg, Iron – 25 mg, Manganese - 80 mg, Copper - 2 mg, Zinc – 50 mg, Cobalt - 1.2 mg and Selenium - 0.1 mg.

 

Data collection

Growth performance

Over a ten-week trial period, the average daily weight gain (ADWG), average daily feed intake (ADFI), final body weight and feed conversion ratio (FCR) were measured, along with mortality.

Blood collection and analysis

Blood samples were taken from two randomly chosen rabbits from each replicate group at the end of the experiment (n = 36). Sterilized syringes and needles were used to draw around 5 ml of blood from the external ear vein into two clearly labelled tubes (with or without anticoagulants) and transported immediately with an ice pack container to the laboratory for analysis. Packed cell volume, white blood cell, red blood cell, and haemoglobin were evaluated as haematological parameters, while the serum biochemical indices including total serum protein, creatinine, aspartate aminotransferase, and alanine aminotransferase were evaluated following standard procedures (Schalm et al., 1975). 

Carcass characteristic and internal organs analysis

On the 70th day of the experiment, 36 rabbits (all healthy rabbits: n=2/replicate for each treatment group of feed type and housing) were randomly picked for slaughtering and further analysis. They were fasted for six hours and slaughtered by cutting the carotid arteries and jugular veins after electrical stunning. The Slaughter and carcass dissection procedures were by the recommendation of the World Rabbit Science Association (Blasco and Ouhayoun 1996). Data on carcass weight, dressing-out percentage, liver, heart, lungs, kidney and spleen weight were collected.

Dressing-out percentage (DP)% = (carcass weight / live weight) x 100

Statistical analysis

For the factorial experiment in a completely randomized design for growth performance and haemato-biochemical variables with feeding and housing systems as the major influence, the data collected were subjected to analysis of variance using the general linear model procedure (PROC GLM) of SAS. Duncan’s multiple range test of the same software was used to separate the difference in means. A significant difference was arrived at when p<0.05. The experimental model used was:

Yijk = µ + Hi + Fj + (HF)ij + eijk

Where Yij = individual observation; µ = population mean; Hi = effect of housing system (i = 1-3); Fj = effect of feeding system (j = 1-3); (HF)ij = interaction effect of housing and feeding system; eijk = expected error

Results and Discussion

Results of the main and interaction effects between the housing and feeding systems are provided separately.

 

Table 2: Main effect of housing type on the growth performance of growing rabbit over 70 day’s trial (n=90).

Parameters	H1	H2	H3	SEM	P-value
IBW (kg)	0.94	0.93	0.90	0.52	0.175
FBW (kg)	1.47c	1.90ab	1.95a	0.55	0.020
ABWG (kg)	0.53c	0.97b	1.05a	0.36	0.029
AFI (kg)	6.04	6.67	6.64	0.11	0.144
FCR	4.10a	3.51b	3.41c	0.06	0.033
Mortality (%)	0.00	0.00	0.00	0.00	0.00

 

abc means along the same row with similar superscripts are not significantly (P > 0.05) different using Duncan’s test as post hoc analysis. IBW: initial body weight; FBW: final body weight; ABW: average body weight gain; AFI: average feed intake; FCR: feed conversion ratio; H1: pen with litter floor; H2: pen with soil floor; H3: battery cage system.

 

Table 2 displays how housing types affect rabbit growth performance. Each of the growth performance measured, including final body weight (FBW), average body weight gain (ABWG), and feed conversion ratio (FCR) were all affected significantly (p<0.05), except for the average feed intake (AFI). Battery cage housing type had the highest FBW and best FCR that is significantly higher (p<0.05) as compared to other treatments, however, the effect of housing type (H2) concrete pen with soil filled floor on FBW was similar (p<0.05) to the battery cage housing type.

 

Table 3: Main effect of feeding systems on the growth performance of growing rabbits (n=90).

Parameters	F1	F2	F3	SEM	P-value
IBW (kg)	0.98	0.97	0.99	0.09	0.172
FBW (kg)	1.05c	1.88b	2.07a	0.05	0.001
ABWG (kg)	0.07c	0.91ab	1.08a	0.08	0.001
AFI, kg	4.51c	5.90b	6.24a	0.04	0.046
FCR	4.30a	3.14b	3.01b	0.03	0.003
Mortality	0.00a	0.00	0.00	0.00

 

abc means along the same row with similar superscripts are not significantly (P > 0.05) different using Duncan’s test as post hoc analysis. IW: initial weight; FBW: final body weight; ABWG: average body weight gain; AFI: average feed intake; FCR: feed conversion ratio; F1 – forage, F2 –concentrate only, F3 -forage with concentrate.

 

The effect of different feeding systems on growth performance of growing rabbits is shown in Table 3. Rabbits fed the forage-concentrate mixture (F3) had the highest (p<0.05) average body weight gain (ABWG), FBW, AFI and best FCR. However, the effect of concentrate feed (F2) alone on the ABWG of growing rabbits was similar (p>0.05) to that of F3. The interaction effect of housing and feeding systems on the growth performance of growing rabbits is shown in Table 4. The interaction effects of housing and feeding systems were significant (p<0.05) for all the measured growth performance parameters. The combined impact of H2xF3 produced the highest (p<0.05) ABWG. The interaction effect of F3 with all housing types gave the highest value (p<0.05) as compared to other combinations. However, the interaction effect on AFBW, AFI, and FCR saw that H3xF3 had the highest value and best FCR (p<0.05), respectively. Similarly, it was observed that the interaction effect of F3 with all housing types gave the highest value (p<0.05) as compared to other combinations for all measured growth parameters.

 

Table 4: Interaction effect of housing and feeding systems on the growth performance of growing rabbit (n=90).

Parameters	Housing type	Feeding system	Interactions		SEM	P value
ABWG (kg)	H1	F1 F2 F3	H1xF1 H1xF2 H1xF3	0.56c 1.11b 1.62a	0.07	0.038
	H2	F1 F2 F3	H2xF1 H2xF2 H2xF3	0.55c 1.12b 1.72a
	H3	F1 F2 F3	H3xF1 H3xF2 H3xF3	0.53c 1.45b 1.53a
AFBW (kg)	H1	F1 F2 F3	H1xF1 H1xF2 H1xF3	1.20c 1.67b 1.75a	0.05	0.043
	H2	F1 F2 F3	H2xF1 H2xF2 H2xF3	1.44c 1.81ab 1.83a
	H3	F1 F2 F3	H3xF1 H3xF2 H3xF3	1.50c 1.87b 1.98a
AFI (kg)	H1	F1 F2 F3	H1xF1 H1xF2 H1xF3	4.13c 5.28b 6.33a	0.03	0.041
	H2	F1 F2 F3	H2xF1 H2xF2 H2xF3	4.16c 6.30ab 6.28a
	H3	F1 F2 F3	H3xF1 H3xF2 H3xF3	4.11c 6.31ab 6.33a
FCR	H1	F1 F2 F3	H1xF1 H1xF2 H1xF3	4.04a 3.24b 3.20bc	0.02	0.026
	H2	F1 F2 F3	H2xF1 H2xF2 H2xF3	4.01a 3.25b 3.21bc
	H3	F1 F2 F3	H3xF1 H3xF2 H3xF3	4.01a 3.21bc 3.19c

 

abc means with similar superscripts down to the column are not significantly (P > 0.05) different. *; P<0.05. IW: initial weight; FW: final weight; ABW: average body weight; AFI: average feed intake; FCR: feed conversion ratio; F1 – forage, F2 –concentrate only, F3 -forage with concentrate; H1: pen with litter floor; H2: pen with soil floor; H3: battery cage system.

 

Table 5: Main effect of different feeding system on the blood indices of growing rabbit (n=36).

Parameters	F1	F2	F3	SEM	p-value
Haematology
WBC (x109/µl)	10.05a	7.72b	7.51b	0.70	0.028
RBC (x1012/µl)	3.32c	4.41b	5.70a	0.42	0.042
Hb (g/dL)	11.16c	13.72b	15.14a	0.60	0.045
PCV (%)	38.01c	41.18ab	45.11a	1.38	0.041
Serum biochemical indices
Tp (g/dL)	76.25	76.77	76.65	0.50	0.083
Creatinine (mg/dl)	0.85	0.71	0.91	4.50	0.238
ALT (U/L)	39.75	31.61	30.01	6.35	0.334
AST (U/L)	89.34	90.75	90.10	6.10	0.121

 

ab “Means along the same row with similar superscripts are not significantly (P > 0.05) different using Duncan’s test as post hoc analysis”. WBC = White blood cell, RBC = Red blood cell, Hb = Haemoglobin, PCV = Pack cell volume, Tp = Total protein, ALT= Alanine aminotransferase, AST = Aspartate aminotransferase”, F1 – forage, F2 –concentrate only, F3 -forage with concentrate”.

 

Table 6: Main effect of different housing typeon the blood indices of growing rabbit (n=36).

Parameters	H1	H2	H3	SEM	p-value
Haematology
WBC (x109/L)	10.79a	8.30c	9.88ab	0.70	0.002
RBC (x1012/L)	4.32b	5.41a	5.75a	0.42	0.041
Hb (g/dL)	11.16c	14.72a	13.44a	0.60	0.042
PCV (%)	37.1c	45.28a	42.41ab	1.38	0.037
Serum biochemical indices
Tp (g/dL)	76.15	70.10	70.17	0.50	0.062
Creatinine (µmol/L)	1.85	1.71	1.72	4.50	0.073
ALT (IU/L)	39.75	38.61	38.9	6.35	0.061
AST (IU/L)	91.34	81.75	93.10	6.10	0.064

 

abc Means along the same row with similar superscripts are not significantly (P > 0.05) different using Duncan’s test as post hoc analysis”. WBC = White blood cell, RBC = Red blood cell, Hb = Haemoglobin, PCV = Pack cell volume, ALT= Alanine aminotransferase, AST = Aspartate aminotransferase, H1: pen with litter floor; H2: pen with soil floor; H3: battery cage system.

 

The main effect of different feeding systems on the blood indices of growing rabbits is shown in Table 5. The combined feed type (F3) promoted the highest (p<0.05) red blood cell count (RBC), haemoglobin (Hb) and packed cell volume (PCV) compared to F2 and F1. Feeding rabbits with forage alone produced the highest (p<0.05) WBC but the lowest (p<0.05) in other haematological parameters. However, the effect of the different feeding systems was not significant (p>0.05) on the measured serum biochemical indices. The main effect of different housing systems on the blood indices of growing rabbits is shown in Table 6. Concrete pen with litter filled floor (H1) promoted the highest (p<0.05) WBC, which is not significant (p>0.05) from battery cage (H3). RBC, Hb and PCV were not significant (p>0.05) for H2 and H3 but were different (p<0.05) for H1. In the same line, the effect of the different housing types was not significant (p>0.05) on the measured serum biochemical indices.

 

Table 7: The interaction effect of the housing and feeding systems on the haematological indices of growing rabbits (n=36).

Parameters	Housing type	Feeding system	Interactions		SEM	P value
WBC (x109/L)	H1	F1 F2 F3	H1xF1 H1xF2 H1xF3	12.76a 10.01b 8.62c	0.70	0.022
	H2	F1 F2 F3	H2xF1 H2xF2 H2xF3	10.15b 9.72bc 7.05c
	H3	F1 F2 F3	H3xF1 H3xF2 H3xF3	12.45a 10.05b 9.33bc
RBC (x1012/L)	H1	F1 F2 F3	H1xF1 H1xF2 H1xF3	3.40 4.03 4.53	0.92	0.130
	H2	F1 F2 F3	H2xF1 H2xF2 H2xF3	4.36 5.01 5.85
	H3	F1 F2 F3	H3xF1 H3xF2 H3xF3	3.75 4.61 4.88
Hb (g/dL)	H1	F1 F2 F3	H1xF1 H1xF2 H1xF3	10.04 12.24 12.20	0.60	0.082
	H2	F1 F2 F3	H2xF1 H2xF2 H2xF3	10.91 13.75 12.49
	H3	F1 F2 F3	H3xF1 H3xF2 H3xF3	10.02 12.02 13.28
PCV (%)	H1	F1 F2 F3	H1xF1 H1xF2 H1xF3	42.04 40.14 44.12	1.40	0.111
	H2	F1 F2 F3	H2xF1 H2xF2 H2xF3	44.91 42.75 42.19
	H3	F1 F2 F3	H3xF1 H3xF2 H3xF3	41.02 41.62 42.58

 

abc means along the same row with similar superscripts are not significantly (P > 0.05) different using Duncan’s test as post hoc analysis, IW: initial weight; FW: final weight; ABW: average body weight; AFI: average feed intake; FCR: feed conversion ratio; F1 – forage, F2 –concentrate only, F3 -forage with concentrate; H1: pen with litter floor; H2: pen with soil floor; H3: battery cage system.

 

Table 8: The interaction effect of the housing and feeding systems on the serological indices of growing rabbits (n=36).

Parameters	Housings	Feedings	Interactions		SEM	P value
Total serum protein (g/dL)	H1	F1 F2 F3	H1xF1 H1xF2 H1xF3	70.76 73.01 71.62	0.30	0.212
	H2	F1 F2 F3	H2xF1 H2xF2 H2xF3	75.15 75.72 76.05
	H3	F1 F2 F3	H3xF1 H3xF2 H3xF3	71.09 72.45 73.33
Creatinine (µmol/L)	H1	F1 F2 F3	H1xF1 H1xF2 H1xF3	1.40 1.43 1.53	0.65	0.080
	H2	F1 F2 F3	H2xF1 H2xF2 H2xF3	1.36 1.31 1.35
	H3	F1 F2 F3	H3xF1 H3xF2 H3xF3	1.55 1.61 1.58
ALT (IU/L)	H1	F1 F2 F3	H1xF1 H1xF2 H1xF3	30.04 32.24 34.20	0.70	0.111
	H2	F1 F2 F3	H2xF1 H2xF2 H2xF3	30.91 33.75 35.49
	H3	F1 F2 F3	H3xF1 H3xF2 H3xF3	30.02 35.02 33.28
AST (IU/L)	H1	F1 F2 F3	H1xF1 H1xF2 H1xF3	92.04 90.14 94.12	1.13	0.091
	H2	F1 F2 F3	H2xF1 H2xF2 H2xF3	90.91 92.75 96.19
	H3	F1 F2 F3	H3xF1 H3xF2 H3xF3	91.02 98.62 96.58

 

abc means along the same row with similar superscripts are not significantly (P > 0.05) different using Duncan’s test as post hoc analysis; IW: initial weight; FW: final weight; ABW: average body weight; AFI: average feed intake; FCR: feed conversion ratio; F1 – forage, F2 –concentrate only, F3 -forage with concentrate; H1: pen with litter floor; H2: pen with soil floor; H3: battery cage system.

 

The interaction effect of housing and feeding systems on the haematological indices of growing rabbits is shown in Table 7. The interaction effects of housing and feeding systems were insignificant (p>0.05) on the RBC of experimental rabbits. However, the highest (p<0.05) values of WBC were recorded in the interactions of H1xF1, and H3xF1 as compared to others. The values recorded for Hb and PCV in the experimental rabbits were not significantly (p>0.05) different across the experimental treatments. The interaction effect of housing and feeding systems on serological indices of rabbits was not (p>0.05) significant as shown in Table 8.

The main effect of housing and feeding systems as presented in Tables 9 and 10 shows that carcass weight and dressing out percentage of rabbits are significantly (p<0.05) different across the treatments. Rabbits on H3 and F3 had the highest value (p<0.05) for both measured parameters, respectively. Other measured parameters were not (p>0.05) affected by the treatment. The interaction effect of housing x feeding systems on carcass weight and dressing out percentage were the only parameters that were significantly (p<0.05) affected as shown in Table 11. H3 x F3 and H1 x F1 had the highest and lowest values (p<0.05). 

 

Table 9: Main effect of housing type on the carcass and relative internal organs (% slaughter weight) of growing rabbit at 70th day’s trial (n =36).

Parameters	H1		H2	H3	SEM	P-value
Carcass weight (kg)	0.93c		1.15ab	1.17a	0.42	0.045
Dressing-out percentage	50.47c		58.10ab	61.95a	3.55	0.030
Liver (g)	2.45		2.48	2.53	0.16	0.91
Heart (g)	0.22		0.24	0.26	0.01	0.34
Lung (g)	0.38		0.39	0.40	0.06	0.41
Kidney (g)	0.44		0.42	0.44	0.03	0.42
Spleen (g)	0.02	0.04		0.03	0.05	0.51

 

abc means along the same row with similar superscripts are not significantly (P > 0.05) different using Duncan’s test as post hoc analysis. IBW: initial body weight; FBW: final body weight; ABW: average body weight gain; AFI: average feed intake; FCR: feed conversion ratio; H1: pen with litter floor; H2: pen with soil floor; H3: battery cage system.

 

Table 10: Main effect of feeding systems on the carcass and relative internal organs (% slaughter weight) of growing rabbit at 70th day’s trial (n =36).

Parameters	F1	F2	F3	SEM	P-value
Carcass weight (kg)	0.72b	1.14b	1.24a	0.09	0.025
Dressing-out percentage (%)	48.05c	55.88b	62.07a	5.05	0.001
Liver (g)	2.75	2.68	2.73	0.18	0.91
Heart (g)	0.27	0.25	0.26	0.03	0.25
Lung (g)	0.40	0.36	0.40	0.04	0.51
Kidney (g)	0.52	0.45	0.54	0.02	0.35
Spleen (g)	0.05	0.02	0.05	0.01	0.31

 

abc means along the same row with similar superscripts are not significantly (P > 0.05) different using Duncan’s test as post hoc analysis; IW: initial weight; FW: final weight; ABWG: average body weight gain; AFI: average feed intake; FCR: feed conversion ratio; F1 – forage, F2 –concentrate only, F3 -forage with concentrate.

 

Table 11: The interaction effect of the housing and feeding systems on the carcass and relative internal organs (% slaughter weight) of growing rabbit at 70th day’s trial (n =36).

Parameters	Housings	Feedings	Interactions		SEM	P value
Carcass weight (kg)	H1	F1 F2 F3	H1xF1 H1xF2 H1xF3	0.76d 0.98c 1.10ab	0.30	0.02
	H2	F1 F2 F3	H2xF1 H2xF2 H2xF3	0.85d 1.02b 1.15ab
	H3	F1 F2 F3	H3xF1 H3xF2 H3xF3	0.92c 1.17b 1.23a
Dressing- percentage (%)	H1	F1 F2 F3	H1xF1 H1xF2 H1xF3	48.40b 50.03bc 53.51a	0.65	0.030
	H2	F1 F2 F3	H2xF1 H2xF2 H2xF3	48.76b 52.01bc 55.05a
	H3	F1 F2 F3	H3xF1 H3xF2 H3xF3	49.85c 52.61ab 57.18a

 

abc means along the same row with similar superscripts are not significantly (P > 0.05) different using Duncan’s test as post hoc analysis; IW: initial weight; FW: final weight; ABW: average body weight; AFI: average feed intake; FCR: feed conversion ratio; F1 – forage, F2 –concentrate only, F3 -forage with concentrate; H1: pen with litter floor; H2: pen with soil floor; H3: battery cage system.

 

Studies have indicated that rabbits housed in battery cages perform better in terms of growth than pen-housed rabbits, which usually perform worse (Szendro and Dalle-Zotte, 2011). However, some studies reported no change in live performance when rabbits were maintained in either pens or cages (Krunt et al., 2020; Matics et al., 2014). The housing system in this experiment affected the final body weight, average body weight and FCR. This study’s findings regarding the impact of housing on growth performance were consistent with those of several other researches (Prajapati et al., 2019; Dal Bosco et al., 2002). A similar effect of non-significance on growing rabbits’ feed intake in cages or pens has been reported (Szendro et al., 2015). However, Matics et al. (2014) averred a significantly lower average body weight gain and average final body weight for rabbits housed in pens with straw litter than in battery cages or elevated wired platforms. The authors attributed the depression in daily gain to a much-increased consumption of litter materials by the rabbits, as observed in the significantly lowered feed intake. Szendro and Dalle (2011), on the other hand, explained the slower growth seen in rabbits raised in pens as being caused by their higher level of physical activity, thus depleting the ingested energy. The continual energy loss from high locomotive activity that occurs when bunnies are confined in pens typically causes chronic stress, which lowers body weight gain (Szendro et al., 2009). 

In this study, the varieties of feed groups adopted substantially impacted the growth performance of rabbits. The high crude fibre concentration in T. procumbens could make it less preferable to concentrate with a much lower crude fibre level (Odeh et al., 2022). Our report contrasts with other authors (Gidenne et al., 2010; Gomez-Conde et al., 2009), who reported improved digestive health and reduced mortality in growing rabbits fed forage with high fibre. The higher but similar feed intakes in the F2 and F3 rabbit groups indicate that they were more palatable than ordinary forage (F1) due to their high crude protein content. This higher feed intake contributed to their much-increased final weight and average daily weight gain. A similar observation was reported by Iyeghe-Erakpotobor (2007) on growing rabbits fed with different concentrate and forage types. Compared to other feeding systems, the lowest FCR recorded for F1 resulted from the lowest AFI and ABWG. This finding agrees with Odeh et al. (2022) and Hasanat et al. (2006), who reported increased daily weight gain from a rabbit-fed concentrate diet. Feeding forage alone would not sustain appropriate growth performance, according to Iyeghe-Erakpotobor et al. (2015). Rabbits can thrive by consuming forage diets. However, a mixed feeding regimen that includes both forages and concentrates improves performance (Arijeniwa et al., 2000). This study suggests that better growth performance can be achieved when rabbits are fed a combination of concentrate and forage (F3). This was further bolstered by the significant interaction effect of housing and feeding types on the various growth performance parameters. The measured growth performance indices are at their best when feed type F3 is combined with either housing H3 or H2. Our current findings also align with Rahman et al. (2020) who reported rabbits as pseudo-ruminants, able to digest forages and concentrates. This result corroborated previous findings of Akinmoladun et al. (2018) and Nworgu et al. (2000), who found higher daily weight gain in rabbits on the dietary mixture (concentrate and forages) compared to those fed forages alone. However, other studies have reported higher weight gains in rabbits fed with concentrate alone compared to a dietary mixture (Christopher et al., 2023; Nworgu et al., 2000).

The assessment of haematological parameters provides valuable insights into the physiological status of animals and their response to various physiological situations, as noted by Esonu et al. (2006). As Daramola et al. (2005) noted, these metrics can also be used as a benchmark for comparison in situations involving nutrient deprivation, physiological changes, and animal health conditions. The significant effect of housing types on all the haematological indices of rabbits in this study contradicts what Szendro et al. (2015) reported, who observed no difference (p>0.05) between battery cage and deep litter on the haematology of growing rabbits. However, the mean values of WBC (7.51-10.05 x 109/L) for the main effects of feeding and housing types were close to the normal physiological range for rabbits (Wiley-Blackwell, 2011; Mitruka and Rawnsley, 1977). Hence, this suggests that the defence mechanisms of the rabbits were not compromised. The range of Hb (11.16-15.14 g/dl) and PCV (38.01-45.11 %) for the main effects in this study were within the reported range of 10-17.4g/dl or 9.0-21.3g/dl and 33.0-50.0% or 27-57% (Bennette and Hawkey, 1988) for Hb and PCV respectively. This normal range of PCV and Hb reflects that the rabbits were in good health and were not dehydrated or anaemic. The amount of protein that is readily available influences the production of serum protein and albumin (Qian et al., 2022). The non-significant (p>0.05) housing and feeding type effect on serum protein could indicate that protein synthesis was not compromised. Although the serum biochemical indices were within the normal range (Hewitt et al., 1989). Studies have demonstrated that the kind and amount of dietary protein affects the levels of creatinine and total protein (Qian et al., 2022). Excess creatinine in the blood is typically caused by enhanced creatinine phosphate catabolism in specific illness states (such as muscle wasting) (Zsolt et al., 2019). 

As reported in Table 7, the significant interaction effect of housing and feeding types on WBC indicated that both factors are capable of interfering with the body defence mechanism of the treated animals. The measured WBC blood performance indices were at the highest when fed feed type F1 was combined with either housing H1 or H3. This may imply that feeding rabbits 100% forage may decline the ability of rabbits to fight infection, while housing type on litter (H1) and battery cage with mesh floor (H3) could expose the rabbits to infection due to direct access to feaces and cage fatigue respectively (Togun et al., 2007). The values of measured WBC are within the normal range for healthy rabbit (Wiley-Blackwell, 2011). Yet, the results of this study show that serum transaminases were within the normal range (Wiley-Blackwell, 2011; Mitruka and Rawnsely, 1977). Hence, the housing and feed systems support growing rabbit production without deleterious effects on their immune status.

The results for the main effect of housing and feeding type as presented in Tables 9 and 10, respectively show that both carcass weight and dressing percentage of rabbits were significantly affected (p<0.05). The significant interaction (p<0.05) effect was at the highest for both carcass weight and dressing percentage when H3 and F3 were combined and with other housing or feeding types. These findings are related to the significant difference in final body weight as earlier reported for main and interaction effects. These results corroborate those of (Dalle et al., 2015; Szendro et al., 2009). The no significant (p>0.05) effect observed in the main effect of housing and feeding type with their interaction on measured organ weights shows that the treatments do not have any negative effect on the weight of measured organ parameters.

 Conclusions and Recommendations

The findings indicated that the three housing systems could be used effectively for rabbit production based on the data recorded in these findings. The battery cage system had the highest average body weight gain and FCR. However, the concrete pen with the soil filled floor system may be considered a suitable alternative housing systems because it satisfies the specific requirement of rabbits and also allays the ethical concern related to animal welfare in modern livestock production. Feeding forages only to growing rabbits or concentrate only as their main diet should be done cautiously due to disrupting the gastrointestinal tracts. On the other hand, a feeding system of concentrate or a combination of forage and concentrate yielded good results. 

Acknowledgements

The authors acknowledge Bowen University for the opportunity to use the University teaching and research farm and laboratory for data collection and laboratory analysis.

Novelty Statement

The study’s originality focuses on the interaction effect of housing and feeding types on physiological performance of growing rabbits.

Author’s Contribution

AM and SK: Conceptualization, methodology, software. SK, AM and AF: Data curation, writing, original draft preparation. AM and OA: Visualization, investigation. LT: Supervision. OA and FT: Software, validation. AM, AF and SK: Writing- reviewing and editing.

Funding

The authors report that no funding was obtained for this study

Data availability statement

All the information and results used to complete the writing of this article are contained in the manuscript.

Conflict of interest

The authors have declared no conflict of interest.

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