Effects of different space allowances on growth performance, blood profile and pork quality in a grow-to-finish production system

Article information

Asian-Australas J Anim Sci.. 2017;30(12):1796-1802
Publication date (electronic) : 2017 June 26
doi : https://doi.org/10.5713/ajas.17.0076
1Department of Agricultural Biotechnology, College of Animal Life Sciences, Seoul National University, Seoul 08826, Korea
*Corresponding Author: Y. Y. Kim, Tel: +82-2-878-5838, Fax: +82-2-878-5839, E-mail: yooykim@snu.ac.kr
Received 2017 February 13; Revised 2017 April 25; Accepted 2017 May 24.

Abstract

Objective

This experiment was conducted to evaluate the optimal space allowance on growth performance, blood profile and pork quality of growing-finishing pigs.

Methods

A total of ninety crossbred pigs [(Yorkshire×Landrace)×Duroc, 30.25±1.13 kg] were allocated into three treatments (0.96: four pigs/pen, 0.96 m2/pig; 0.80: five pigs/pen, 0.80 m2/pig; 0.69: six pigs/pen, 0.69 m2/pig) in a randomized complete block design. Pigs were housed in balanced sex and had free access to feed in all phases for 14 weeks (growing phase I, growing phase II, finishing phase I, and finishing phase II).

Results

There was no statistical difference in growing phase, but a linear decrease was observed on average daily gain (ADG, p<0.01), average daily feed intake (ADFI, p<0.01), and body weight (BW, p<0.01) with decreasing space allowance in late finishing phase. On the other hand, a quadratic effect was observed on gain to feed ratio in early finishing phase (p<0.03). Consequently, overall ADG, ADFI, and final BW linearly declined in response to decreased space allowance (p<0.01). The pH of pork had no significant difference in 1 hour after slaughter, whereas there was a linear decrease in 24 h after slaughter with decreasing space allowance. Floor area allowance did not affect pork colors, but shear force linearly increased as floor space decreased (p<0.01). There was a linear increase in serum cortisol concentration on 14 week (p<0.05) with decreased space allocation. Serum IgG was linearly ameliorated as space allowance increased on 10 week (p<0.05) and 14 week (p<0.01).

Conclusion

Data from current study indicated that stress derived from reduced space allowance deteriorates the immune system as well as growth performance of pigs, resulting in poor pork quality. Recommended adequate space allowance in a grow-to-finish production system is more than 0.80 m2/pig for maximizing growth performance and production efficiency.

INTRODUCTION

Large-scale intensive pig farming system has been rising globally due to increase of market demands for pork products during the last two decades [1]. As the public interest in animal welfare increases to the livestock animals, pork producers are confronted with both profitability and welfare issues, although these seem inversely related [2].

Operation of intensive pig production causes various problems, such as growth disturbance, immune dysfunction, risk of exposure to respiratory disease and pork quality deterioration [3,4]. Several studies have been conducted to establish the appropriate space allowance for pigs. NRC [5] recommended the minimum space for maximum ME intake as reported by [6]. The European Union (EU) also established space requirements which were mandated by law (Council Directive 2001/88/EC). Korean Government also legislated space requirements with 0.45 m2/pig in growing phase (30 to 60 kg) and 0.8 m2/pig in finishing phase (>80 kg). However, this regulation is only applicable in traditional three stage management systems (weaning, growing, and finishing barn), not the grow-to-finish production systems which are advocated largely because of the ease of management in large-scale farming. However, there is little scientific data available to evaluate the effects of different space allowance on growth performance and pork quality in a grow-to-finish production system.

Therefore, this study evaluated the effect of different space allowance in growing-finishing pigs housed in grow-to-finish production system on productivity as well as economic efficiency.

MATERIALS AND METHODS

Animal care

This experimental protocol was approved by the Ethical Committee for Institutional Animal Use and Care of the Seoul National University (SNU-160613-10). The experiment was conducted at the facility of Seoul National University farm located in Suwon-si, Gyeonggi-do, Republic of Korea.

Animals, experimental designs, diets and housing

A total of 90 crossbred ([Yorkshire×Landrace]×Duroc) pigs, averaging 30.30±1.13 kg initial body weight (BW), were randomly allocated based on initial BW and sex according to randomized complete block (RCB) design with six replicates. Pen size was 1.60×3.00 m, with space allocation achieved by varying the number of pigs per pen. Treatments were i) 0.96 (0.96 m2/pig, 4 pigs/pen); ii) 0.80 (0.80 m2/pig, 5 pigs/pen); and iii) 0.69 (0.69 m2/pig, 6 pigs/pen). A corn-soybean meal based commercial feed was used for 3 phases, including growing (0 to 6 weeks), early finishing (7 to 10 weeks) and late finishing period (10 to 14 weeks). Calculated nutrient contents of the experimental diets are presented in Table 1. Floors were partially slatted, and a climate computer regulated ventilation and heating in the compartments. Temperatures varied between 15°C and 20°C. Lighting was provided in combination with a several windows and fluorescent lights. Each pen had one nipple drinker and feeder. Animals were fed diet and water ad libitum during the entire experimental period. The BW and feed consumption were recorded at initial, 3, 6, 10, and 14 weeks to calculate average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio (G/F ratio). Pigs that were removed were weighed and the feed intake and G:F ratio was adjusted based on a model to estimate individual feed intake [7].

Calculated nutrient contents of experimental diets

Sampling and measurements

Six randomly selected pigs in each treatment were sacrificed for blood sampling. A 10 mL blood sample from each individual, taken by jugular vein at the same time of measuring BW, was collected in a disposable vacutainer tube without anticoagulant (BD Vacutainer K2E, Becton Dickinson, Plymouth, UK). Then, samples were centrifuged at 3,000 rpm at 4°C for 15 min (Eppendorf centrifuge 5810R, Hamburg, Germany) to separate serum. Samples were stored at −20°C and analyzed for determination of blood urea nitrogen (BUN), cortisol, immunoglobulin A (IgA), and G (IgG). Total BUN concentration was analyzed using a blood analyzer (Ciba-Corning model, Express Plus, Ciba Corning Diagnostics Co., Irvine, MA, USA). For cortisol analysis, samples were analyzed in duplicate within a single assay. Cortisol concentrations were measured using a Coat-a-Count assay kit (Diagnostic Products, Los Angeles, CA, USA). For immunological parameters, serum IgG and IgA of pigs were determined by enzyme-linked immunosorbent assay assay according to the manufacture’s protocols (Bethyl Laboratories Inc., Montogomery, TX, USA). The assay was analyzed in duplicate on each serum sample. The assay dynamic range of IgA and IgG were both 15.6 to 10,000 ng/mL.

Pork quality

At the end of experiment, six pigs from each treatment were randomly selected and slaughtered at average 115.98±0.84 kg for the carcass analysis. Pork samples were collected from nearby 10th rib on right side of carcass. After chilling, 1 hour after slaughter was regarded as the initial time. The proximal loin meat was analyzed for dry matter, crude protein, crude fat, and crude ash according to the method of the Association of Official Analytical Chemists [8]. Pork pH and color of longissimus muscle were measured 2 times, 1 h and 24 h after slaughter, respectively. The pH was measured using a pH meter (Φ 500 Series, Bechman Coulter, S. Kraember Blvd Brea, CA, USA) and pork color was measured by Commission Internationale de l’Eclairage color L*, a*, and b* values using a chroma meter (CR-300, Konica Minolta Co., Osaka, Japan). Water holding capacity of pork was measured by centrifuge method [9]. To calculate the cooking loss, longissimus muscles were packed in a polyethylene bag and heated in water bath until core temperature reached 72°C. Weight difference, before and after heating, was regarded as cooking loss. For shear force analysis, samples are cored (0.5×1.0×1.5 cm) parallel to muscle fiber and the cores were used to measure the shear force using a tabletop Warner-Bratzler shear force machine (Saltner Brecknell, Model 235 6X: Motor for Shearer: Bodine Electric Company, Small Motor S/N 0291KUIL 0009 Chicago, IL, USA).

Mortality and economic analysis

A total of 12 pigs were excluded from the experiment (Table 6). Data correction for the ADFI for replication with excluded pigs was adjusted considering the maintenance energy and growth energy of the excluded pigs followed by Kim and Lindemann et al [7]. Pen size was not corrected in the event of pig death or removal. For economic analysis, the days to market weight (115 kg) was calculated from the final body weight and overall ADG (0 to 14 week).

Effect of different space allowance on proximate analysis and physiochemical properties of pork

Statistical analysis

Analyses of variance as a RCB design were conducted using PDIFF option with General Linear Model procedures of SAS 9.3 (SAS Inst., Inc., Cary, NC, USA). The pen of pigs was the experimental unit for growth performance (BW, ADG, ADFI, and G/F ratio), and individual pig was used as the experimental unit in hematological analysis and pork quality evaluation. The effects of increasing levels of space allowance were analyzed as linear and quadratic components by orthogonal polynomial contrasts. Pig removal did not conform to the normal distribution and, consequently, the Kruskal-Wallis rank-based nonparametric test [10] was performed using the PROC RANK procedures of SAS. Statistical differences were considered significant at the level of p<0.05 and highly significant at the level of p<0.01, with a trend between p≥0.05 and p≤0.10.

RESULTS

Growth performance

The effect of different space allowance on growth performance is presented in Table 2. There were no significant differences in BW, ADG, ADFI, and G/F ratio in growing phase (0 to 6 week). However, BW was linearly increased (p<0.01) as space allowance increased in both early (10 week) and late (14 week) finishing phase, respectively. In addition, there were linear increases in ADG (p<0.01) and ADFI (p<0.01) as space allowance increased from 0.69 to 0.96 m2/pig in finishing periods and over the entire experimental period. On the other hand, quadratic response was observed on G/F ratio in late finishing period (p<0.03) and overall period (p = 0.07).

Effect of different space allowance on growth performance in growing-finishing pigs

Hematological analysis

Space allocation did not affect BUN concentration in growing-finishing pigs, whereas, serum cortisol level linearly elevated with space allowance decreased (p<0.05) in 14 week (Table 3).

Effect of different space allowance on serum cortisol and BUN concentration

The effect of different space allowance on immunological parameters are shown in Table 4. There were no detectible differences in serum IgA concentration in 3, 6, 10, and 14 weeks, whereas IgG was linearly increased as space allocation increased in 10 and 14 weeks (p<0.01 and p<0.02, respectively).

Effect of different space allowance on immunological response in growing-finishing pigs

Pork quality

The more pigs were crowded, the less pH of pork in 24 hour postmortem of carcass (p<0.01, Table 5). In addition, there was linear increase of shear force with decreased space allowance (p<0.01, Table 6).

Effect of different space allowance on pork pH and lightness

Mortality and days to market weight

The effects of different space allowance on mortality and days to market weight are presented in Table 7. Whilst the pigs reared in 0.96 m2 showed the shortest days to market weight (176 days), pigs in 0.69 m2 recorded the longest days to market weight (208 days). Similarly, one pig (1 in growing phase) died in 0.96 treatment, but seven pigs (2 in growing, and 5 in late finishing phase, respectively) died in 0.69 treatment during the overall experimental period.

Effect of different space allowance on mortality and days to market weight

DISCUSSION

The data from the current experiment showed that there were no effect of space allocation on ADFI, ADG, and BW in growing phase. Previous studies have insisted that there are various reasons for the effect of space allowance on growth performance in growing-finishing pigs; reduction in feed intake [11] and changes of behavioral requirement [12]. Brumm et al [3] stated that growing-finishing pigs reared in less than optimal space diminished feed intake, resulting in a reduction in ADG. More recently, White et al [13] reported that reducing stocking density from 0.93 to 0.66 m2/pig resulted in 4.0% less BW, 17.0% less ADG, and 10.7% less ADFI. This finding is in agreement with our study that reduced space allowance from 0.96 to 0.69 m2/pig resulted in less ADG and BW (17.0% and 12.1%, respectively) which might be associated with 14.7% less ADFI.

The coefficient value (k) of space allowance (A, m2/pig) can be expressed using the equation reported by Petherick et al [14]: A = k×BW0.667. Several countries legislated or recommended minimum space requirement for pigs using this formula, which varied from 0.028 to 0.034 for growing-finishing pigs [15]. Moreover, recent study of Gonyou et al [6] demonstrated the relationship between space allowance and ADFI using broken-line analysis. Additionally, the range of critical coefficient value (k) determined by nonlinear analysis for growing-finishing pigs on partial slats was from 0.0357 to 0.0358 (p<0.03 and p<0.01, respectively). Our analysis resulted in an approximation of the critical value of k = 0.045 for 0.69 treatment (0.69 m2/pigs) in growing phase, whereas critical value of k = 0.033 was obtained the in finishing phase. We assumed that growing pigs occupying 0.69 m2 per pig was enough to grow without detrimental effects. This is also supported by the finding that the higher lipid accretion of pigs reared in the spacious pen is due to their higher feed intake, which, when in excess of the energy requirement for protein deposition and maximal lean gain, results in increased accretion ratio of lipid:protein [16].

Cortisol is a steroid hormone or glucocorticoid produced by the adrenal gland and released in response to stress. Generally, a poor welfare situation could lead to extreme stress to animals. Blood cortisol concentration has been the most common physiological parameter used to measure farm animal welfare [17], although the measurement suffers from diurnal variations and sample collection artifacts [18]. The current study showed that space allowance significantly influenced concentration of serum cortisol. This is consistent with the study of Zhang et al [19] who confirmed that the linearly increased cortisol concentration was in relation to higher stress in the pigs with 0.38 m2 per pig than in those with 0.64 m2. These results suggest that a chronic stress response as implied by the linear increase of cortisol concentrations with the higher stocking density may have a detrimental effect on growth performance.

The immune system serves the defense against the stress response in order to maintain homeostasis [20]. Serum IgG and IgA, widely used as an index of humoral immune parameters, are the major immunoglobulins in the extravascular compartment acting against pathogenic viruses and microorganisms [21]. Recent studies by Woof et al [22] have concluded that where there is limited antigen, IgA is able to trigger effector functions that have the potential to destroy micro-organisms and mammalian cells by inhibiting complement activation. Considering our experimental condition, it seems likely that there were enough antigens to properly activate IgA in both treatments. The study of Tuchscherer et al [23] indicates that complement activation of IgG effectively provides the organism with a first line of nonspecific humoral defense against infections before the immune response. Several studies noted that psychological stress can modulate the activation of the complement system [24]. Consequently, chronic stress derived from decreased space allowance might lead to nutritional disruption, resulting in the suppression of the IgG function in the present study.

Previous studies on the influence of space allowance on pork quality characteristics are prone to conflict, because most of studies compared different production systems rather than different environments with in the same system [25]. Brumm et al [3] found that different space allowance did not influenced carcass yield in grow to finish production systems. In contrast, earlier studies of Warriss et al [26] reported that pigs housed in higher density were more likely to produce paler meat than those at lesser density. Enfält et al [27] found a lower ultimate pH, higher drip loss, increased shear force values, and reduced intramuscular fat for outdoor compared to indoor reared pigs. Recent findings of Liorancas et al [25] reported that offering spacious conditions compared to commercial conditions resulted in higher muscle pH 24 hours postmortem, which is concordant with our result. The pH change is a very critical factor to determine pork quality. It has been acknowledged that initial pH is regarded as an indicator of PSE (pale, soft, and exudative) and the final pH is regarded as an estimation of DFD (dark, firm, and dry) pork [28]. The data from our result suggest that decreased spacial allocation increased carcass pH changes. One possible explanation is due to a higher blood cortisol level. Higher levels of blood cortisol were associated with higher pork temperatures, resulting in significantly lower ultimate pH values [29]. Thus, it is more susceptible to develop rapid rigor mortis [30]. Higher cooking loss and more water holding capacity [31] were observed in carcasses with rapid development of rigor mortis. In agreement with those findings, in this study, decreasing muscle glycolytic potential originated from chronic stress negatively influenced the rate of pH decline, resulting a detrimental effect on pork quality.

In the present study, higher mortality was observed in the pigs occupying 0.69 m2, whereas 0.96 m2 was the lowest. In agreement, numerous studies have shown that morbidity levels increase with a decrease in floor space [32]. More recently, Hamilton et al [4] stated that there was a trend for the mortality to be higher for pigs reared in the restricted than the unrestricted floor space.

Days to market weight per pig was shorter in the pigs reared in the largest (0.96 m2) space allowance, but longest in the pigs reared in the small (0.69 m2) space allowance. This finding is rather different from previous studies where the production and economic measures per pig improve with increased space allowance, the production per unit area or at a system level often still declines [6], which implies that the optimum from the pig and producers’ perspective are different [33]. If policy makers make changes that benefit pig welfare, for example, by increasing space allowance, this can result in reduced margins for producers, unless they can obtain a price premium [34]. We cannot characterize increased space allowance as increasing total marginal profits, because we only measured days to market weight. Thus, multi-dimensional analysis is required to understand of the better production system in order to reduce economic loss of the farm.

ACKNOWLEDGMENTS

This work was supported by Korea Institute of Planning and Evaluation for Technology in Food, Agriculture, Forestry and Fisheries (IPET) through Agri-Bio industry Technology Development Program, funded by Ministry of Agriculture, Food and Rural Affairs (MAFRA; 314022-3).

Notes

CONFLICT OF INTEREST

We certify that there is no conflict of interest with any financial organization regarding the material discussed in the manuscript.

References

1. Delgado C, Rosegrant M, Steinfeld H, Ehui S, Courbois C. Livestock to 2020: the next food revolution Food, Agriculture, and the Environment Washington DC, USA: International Food Policy Research Institute; 1999. Discussion Paper No. 28.
2. Rossi R, Costa A, Guarino M, et al. Effect of group size, floor space allowance and floor type on growth performance and carcass characteristics of heavy pigs. J Swine Health Prod 2008;16:304–11.
3. Brumm MC, Ellis M, Johnston LJ, Rozeboom DW, Zimmerman DR. Interaction of swine nursery and grow-finish space allocations on performance. J Anim Sci 2001;79:1967–72.
4. Hamilton DN, Ellis M, Wolter BF, Schinckel AP, Wilson ER. The growth performance of the progeny of two swine sire lines reared under different floor space allowances. J Anim Sci 2003;81:1126–35.
5. National Research Council. Committee on Nutrient Requirements of Swine. Nutrient requirements of swine 11th edth ed. Washington, DC: National Academy Press; 2012.
6. Gonyou HW, Brumm MC, Bush E, et al. Application of broken-line analysis to assess floor space requirements of nursery and grower-finisher pigs expressed on an allometric basis. J Anim Sci 2006;84:229–35.
7. Lindermann MD, Kim BG. Technical note: a model to estimate individual feed intake of swine in group feeding. J Anim Sci 2007;85:972–5.
8. AOAC. Official Methods of Analysis. 10th edth ed. Association of Official Analytical Chemists Arlington, VA, USA: AOAC International; 2000.
9. Kauffman RG, Eikelenboom PG, Van der Wal , Engel B, Zaar M. A comparision of methods to estimate water-holding capacity in post-rigor porcine muscle. Meat Sci 1986;18:307–22.
10. Steel RG, Torrie JH. Principle and procedures of statistic: A biometrical approach New York, USA: Me-Graw Hill Book; 1980. p. 161.
11. Gonyou HW, Chapple RP, Frank GR. Productivity, time budgets and social aspects of eating in pigs penned in groups of five or individually. Appl Anim Behav Sci 1992;34:291–301.
12. Pearce GP, Paterson AM. The effect of space restriction and provision of toys during rearing on the behaviour, productivity and physiology of male pigs. Appl Anim Behav Sci 1993;36:11–28.
13. White HM, Richert BT, Schinckel AP, et al. Effects of temperature stress on growth performance and bacon quality in grow-finish pigs housed at two densities. J Anim Sci 2008;86:1789–98.
14. Petherick JC. A biological basis for the design of space in livestock housing. In : Baxter SH, Baxter MR, McCormack JAC, eds. Farm animal housing and welfare Lancaster, UK: Martinus Nuhoff Publishers; 1983. p. 103–20.
15. The European Community. European Council Directive 2001/88/EC of 23rd October 2001 amending directive 91/630/EEC laying down minimum standards for the protection of pigs. Off. J. L316 (2001/12/01) 2001;
16. Schinckel AP. Describing the pig. In : Kyriazakis I, ed. A quantitative biology of the pig NY, USA: CABI; 1999.
17. Terlouw EM, Schouten WPG, Ladewig J. In : Appleby C, Hughes BO, eds. Physiology in animal welfare Oxon, NY: CABI; 1997.
18. McGlone JJ, Vines B, Rudine AC, DuBois P. The physical size of gestating sows. J Anim Sci 2004;82:2421–7.
19. Zhang ZF, Li J, Park JC, Kim IH. Effect of vitamin levels and different stocking densities on performance, nutrient digestibility, and blood characteristics of growing pigs. Asian-Australas J Anim Sci 2013;26:241–6.
20. Bohus B, Koolhaas JM, Nyakas C, et al. Physiology of stress: a behavioral view. In : Wiepkema PR, van Adrichem PWM, eds. Biology of stress in farm animals: an integrative approach Martinus Nijhoff Publishers; 1987.
21. Li P, Yin YL, Li D, Kim SW, Wu G. Amino acids and immune function. Br J Nutr 2007;98:237–52.
22. Woof JM, Kerr MA. The function of immunoglobulin A in immunity. J Pathol 2006;208:270–82.
23. Tuchscherer M, Puppe B, Tuchscherer A, Kanitz E. Effects of social status after mixing on immune, metabolic, and endocrine responses in pigs. Physiol Behav 1998;64:353–60.
24. Stefanski V, Hendrichs H. Social confrontation in male guinea pigs: behavior, experience, and complement activity. Physiol Behav 1996;60:235–41.
25. Liorancas V, Bakutis B, Januskeviciene G. Influence of rearing space on the behavior, performance, carcass and meat quality of pigs. Medycyna Weterynaryjna 2006;62:274–7.
26. Warriss PD, Kestin SC, Robinson JM. A note on the influence of rearing environment on meat quality in pigs. Meat Sci 1983;9:271–9.
27. Enfält A, Lundström K, Ingemar Hansson KI, Lundeheim N, Nyström PE. Effects of outdoor rearing and sire breed (Duroc or Yorkshire) on carcass composition and sensory and technological meat quality. Meat Sci 1997;45:1–15.
28. Maganhini MB, Mariano B, Soares AL, et al. Meats PSE (pale, soft, exudative) and DFD (dark, firm, dry) of an industrial slaughterline for swine loin. Ciênc Tecnol Aliment 2007;27:69–72.
29. Dokmanovic M, Baltic MZ, Duric J, et al. Correlations among stress parameters, meat and carcass quality parameters in pigs. Asian-Australas J Anim Sci 2015;28:435–41.
30. Warriss D, Brown SN, Knowles TG. Measurements of the degree of development of rigor mortis as an indicator of stress in slaughtered pigs. Vet Rec 2003;153:739–42.
31. Hambrecht E, Eissen JJ, Verstegen MWA. Effect of processing plant on pork quality. Meat Sci 2003;64:125–31.
32. Wolter BF, Ellis M. Impact of large group sizes on growth performance in pigs in the USA. Pigs of News Inf 2002;23:17–20.
33. Jenen T, Kold Nielsen C, Vinther J, D’Eath RB. The effect of space allowance for finishing pigs on productivity and pen hygiene. Livest Sci 2012;149:33–40.
34. Bornett HLI, Guy JH, Cain PJ. Impact of animal welfare on costs and viability of pig production in the UK. J Agric Environ Ethics 2003;16:163–86.

Article information Continued

Table 1

Calculated nutrient contents of experimental diets

Chemical composition Growing phase (0 to 6 week) Early finishing phase (7 to 10 week) Late finishing phase (11 to 14 week)
ME (kcal/kg) 3,650.00 3,650.00 3,650.00
Crude protein (%) 18.50 15.50 14.00
Crude fat (%) 4.00 4.00 4.00
Crude ash (%) 8.00 8.00 8.00
Lysine (%) 1.10 0.70 0.65
Ca (%) 0.60 0.40 0.35
P (%) 1.30 0.80 0.75

ME, metabolizable energy.

Table 2

Effect of different space allowance on growth performance in growing-finishing pigs

Criteria Treatment1) SEM p-value


0.96 0.80 0.69 Linear Quadratic
Body weight (kg)
 Initial 30.14 30.43 30.18 1.23 0.74 0.64
 3 wk 43.78 42.95 42.05 1.79 0.17 0.97
 6 wk 60.70 59.82 59.51 2.10 0.24 0.72
 10 wk 80.15 76.08 73.89 2.05 0.01 0.48
 14 wk 103.94 98.88 91.40 2.79 0.01 0.64
ADG (g)
 0–3 wk 650 596 565 30.73 0.13 0.80
 3–6 wk 806 790 831 23.42 0.60 0.51
 6–10 wk 695 581 514 27.53 0.01 0.45
 10–14 wk 850 814 625 37.95 0.01 0.14
 0–6 wk (Growing) 728 700 698 21.80 0.17 0.45
 6–14 wk (Finishing) 772 697 569 28.23 0.01 0.47
 Overall 753 698 625 20.32 0.01 0.71
ADFI (g)
 0–3 wk 1,524 1,408 1,446 59.86 0.38 0.32
 3–6 wk 2,082 1,919 1,966 59.77 0.30 0.27
 6–10 wk 2,216 1,885 1,722 69.20 0.01 0.22
 10–14 wk 2,575 2,275 2,116 73.88 0.01 0.42
 0–6 wk (Growing) 1,803 1,663 1,706 57.74 0.27 0.23
 6–14 wk (Finishing) 2,398 2,072 1,919 68.60 0.01 0.22
 Overall 2,143 1,876 1,828 55.90 0.01 0.09
G/F ratio
 0–3 wk 0.426 0.424 0.391 0.011 0.28 0.52
 3–6 wk 0.387 0.412 0.423 0.010 0.16 0.74
 6–10 wk 0.313 0.308 0.298 0.011 0.60 0.91
 10–14 wk 0.330 0.358 0.295 0.011 0.12 0.03
 0–6 wk (Growing) 0.404 0.421 0.409 0.005 0.77 0.23
 6–14 wk (Finishing) 0.322 0.337 0.297 0.008 0.28 0.18
 Overall 0.351 0.372 0.342 0.006 0.50 0.07

SEM, standard error of the means.

1)

0.96, 4 growing-finishing pigs/pen (0.96 m2/pig); 0.80, 5 growing-finishing pigs/pen (0.80 m2/pig); 0.69, 6 growing-finishing pigs/pen (0.69 m2/pig).

Table 3

Effect of different space allowance on serum cortisol and BUN concentration

Criteria Treatment1) SEM p-value


0.96 0.80 0.69 Linear Quadratic
Cortisol (μg/dL)
 Initial 2.7 2.7 2.7 - - -
 3 wk 1.4 2.4 2.6 0.432 0.453 0.773
 6 wk 2.0 2.0 3.4 0.689 0.209 0.159
 10 wk 3.6 3.7 4.2 0.396 0.557 0.703
 14 wk 2.3 3.3 4.0 0.498 0.046 0.108
Blood urea nitrogen (mg/dL)
 Initial 11.8 11.8 11.8 - - -
 3 wk 12.3 13.7 10.8 0.467 0.316 0.424
 6 wk 12.5 15.3 15.8 0.970 0.328 0.145
 10 wk 13.8 15.5 14.0 0.342 0.673 0.011
 14 wk 13.7 11.0 11.6 0.545 0.781 0.681

BUN, blood urea nitrogen; SEM, standard error of the means.

1)

0.96, 4 growing-finishing pigs/pen (0.96 m2/pig); 0.80, 5 growing-finishing pigs/pen (0.80 m2/pig); 0.69, 6 growing-finishing pigs/pen (0.69 m2/pig).

Table 4

Effect of different space allowance on immunological response in growing-finishing pigs

Criteria Treatment1) SEM p-value


0.96 0.80 0.69 Linear Quadratic
IgG (mg/dL)
 Initial 2.12 2.12 2.12 - - -
 3 wk 2.61 4.34 2.60 0.605 0.98 0.16
 6 wk 2.52 5.25 4.24 0.570 0.16 0.12
 10 wk 5.27 4.22 2.27 0.414 0.01 0.52
 14 wk 4.04 4.03 2.56 0.266 0.02 0.12
IgA (mg/dL)
 Initial 2.12 2.12 2.12 - - -
 3 wk 2.52 2.31 2.21 0.253 0.65 0.93
 6 wk 2.84 4.87 3.41 0.360 0.54 0.45
 10 wk 5.06 3.25 3.87 0.423 0.25 0.11
 14 wk 4.82 5.52 5.09 0.385 0.50 0.55

SEM, standard error of the means; IgG, immunoglobulin G; IgA, immunoglobulin A.

1)

0.96, 4 growing-finishing pigs/pen (0.96 m2/pig); 0.80, 5 growing-finishing pigs/pen (0.80 m2/pig); 0.69, 6 growing-finishing pigs/pen (0.69 m2/pig).

Table 5

Effect of different space allowance on pork pH and lightness

Criteria Treatment1) SEM p-value


0.96 0.80 0.69 Linear Quadratic
pH
 1 h 5.87 5.87 5.88 0.02 0.85 0.92
 24 h 5.68 5.67 5.62 0.01 0.01 0.09
CIE value L*
 1 h 40.19 39.76 40.79 40.25 0.85 0.79
 24 h 48.02 45.83 46.50 46.78 0.67 0.29
CIE value a*
 1 h 1.54 1.56 1.70 1.60 0.23 0.81
 24 h 4.00 3.51 4.10 3.87 0.28 0.86
CIE value b*
 1 h 3.93 3.82 3.94 3.90 0.23 0.98
 24 h 6.54 5.86 6.27 6.23 0.23 0.48

SEM, standard error of the means; CIE, Commission Internationale de l’Eclairage.

1)

0.96, 4 growing-finishing pigs/pen (0.96 m2/pig); 0.80, 5 growing-finishing pigs/pen (0.80 m2/pig); 0.69, 6 growing-finishing pigs/pen (0.69 m2/pig).

Table 6

Effect of different space allowance on proximate analysis and physiochemical properties of pork

Criteria Treatment1) SEM p-value


0.96 0.80 0.69 Linear Quadratic
Proximate analysis of loin meat
 Dry matter (%) 72.12 71.57 71.33 0.18 0.49 0.32
 Crude protein (%) 23.23 23.15 24.11 0.24 0.07 0.50
 Crude fat (%) 2.37 3.24 3.06 0.16 0.41 0.65
 Crude ash (%) 1.34 1.46 1.39 0.11 0.39 0.19
Physiochemical property
 Cooking loss (%) 33.89 32.09 33.30 0.10 0.46 0.48
 WBS (kg/0.75 cm3) 4.72 5.16 5.38 0.33 0.01 0.49
 WHC (%) 57.03 56.48 55.26 0.41 0.87 0.69

SEM, standard error of the means; WBS, Wamer-Bratzler shear force; WHC, water holding capacity.

1)

0.96, 4 growing-finishing pigs/pen (0.96 m2/pig); 0.80, 5 growing-finishing pigs/pen (0.80 m2/pig); 0.69, 6 growing-finishing pigs/pen (0.69 m2/pig).

Table 7

Effect of different space allowance on mortality and days to market weight

Criteria Treatment1) SEM p-value


0.96 0.80 0.69 Linear Quadratic
Days to market weight (110 kg) 176.04 183.93 207.78 19.724 0.01 0.79
Mortality (%, head)
 Growing phase 0.0 (0) 6.7 (2) 5.5 (2) - - -
 Finishing phase 4.1 (1) 7.1 (2) 14.7 (5) - - -
 Overall 4.1 (1) 13.3 (4) 19.4 (7) - - -

SEM, standard error of the means.

1)

0.96, 4 growing-finishing pigs/pen (0.96 m2/pig); 0.80, 5 growing-finishing pigs/pen (0.80 m2/pig); 0.69, 6 growing-finishing pigs/pen (0.69 m2/pig).