Acta agriculturae Slovenica, 118/4, 1–10, Ljubljana 2022
doi:10.14720/aas.2022.118.4.2808 Original research article / izvirni znanstveni članek
Effects of high vitamin and micro-mineral supplementation on growth 
performance and pork quality of finishing pigs under heat stress
Arth David Sol Valmoria ORTEGA 1, 2, 3, 4, László BABINSZKY 1, Zsófia RÓZSÁNÉ-VÁRSZEGI 5, Xénia 
Erika OZSVÁTH 2, 5, Ogonji Humphrey ORIEDO 6, János OLÁH 7, Csaba SZABÓ 1
Received Avgust 08, 2022; accepted November 11, 2022.
Delo je prispelo 08. avgusta 2022, sprejeto 11. novembra 2022
1 University of Debrecen, Faculty of Agriculture and Food Sciences and Environmental Management, Institute of Animal Science, Biotechnology and Nature, Depart-
ment of Animal Nutrition and Physiology, Debrecen, Hungary
2 University of Debrecen, Doctoral School of Animal Science
3 Central Mindanao University, College of Agriculture, Department of Animal Science, University town, Musuan, Maramag, Bukidnon, 8710, Philippines
4 Corresponding author, e-mail: ortega.david@agr.unideb.hu
5 University of Debrecen, Faculty of Agriculture and Food Sciences and Environmental Management, Institute of Animal Science, Biotechnology and Nature, Depart-
ment of Animal Science, Debrecen, Hungary
6 Department of Agriculture, Livestock and Food Security, Veterinary services section, Country Government of Makueni, 78-90300, Kenya
7 University of Debrecen, Institute for Agricultural Research and Educational Farm, Kismacs Experimental Station of Animal Husbandry, Debrecen, Hungary
Effects of high vitamin and micro-mineral supplementation 
on growth performance and pork quality of finishing pigs un-
der heat stress
Abstract: The objective of this study was to determine the 
effects of heat stress (HS) on the production performance of 
fattening pigs and whether the supplementation of vitamins (C 
and E) and micro-minerals (Se and Zn) at increased concentra-
tions can mitigate HS adverse effects. Thirty six Danbred hybrid 
barrows (65.1 ± 2.81 kg) were randomly distributed into four 
treatments 1) HS (28.9 ± 0.9 °C, RH- 60.4 ± 4.3 %) + control 
diet (HC), 2) HS + diet 1 (HT1), 3) HS + diet 2 (HT2), and 4) 
thermo-neutral conditions (19.5 ± 0.9 °C, RH- 85.9 ± 7.3 %) + 
control diet (TC). Bodyweight and feed intake were measured 
weekly for four weeks. After the experiment, six pigs from each 
treatment were slaughtered, and the longissimus lumborum 
muscle was sampled to evaluate meat quality. At week four, HS 
significantly affected pig body weight (p < 0.05). However, the 
other parameters were not significantly affected by HS,while 
slight improvements in these parameters were observed by sup-
plementing vitamins and micro-minerals in the diet of the pigs 
despite exposure to HS. Therefore, the pigs used in the study 
showed resilience to adverse effects of HS on growth and meat 
quality parameters. The content of vitamins C and E and micro-
minerals Se and Zn in the diet seems to play an important role 
in resilience to HS, therefore their requirement and supplemen-
tation should be carefully evaluated.
Key words: pigs; animal nutrition; heat stress; feed additives; 
vitamins; micro-minerals; growth performance; meat quality
Vpliv dodatka vitaminov in mikrorudninskih snovi v krmo 
za prašiče pitance na prirast in kakovost mesa v pogojih vro-
činskega stresa
Izvleček: Cilj raziskave je bil ugotoviti učinke vročinske-
ga stresa (HS) na prirast prašičev pitancev in ali lahko z do-
dajanjem vitaminov (C in E) in mikrorudninskih snovi (Se in 
Zn) v povečanih koncentracijah ublažimo škodljive učinke HS. 
Šestintrideset kastratov Danbred križancev (65,1 ± 2,81 kg) je 
bilo naključno razdeljenih v štiri skupine 1) HS (28,9 ± 0,9 °C, 
RV- 60,4 ± 4,3 %) + kontrolna krmna mešanica (HC), 2) HS + 
krmna mešanica 1 (HT1), 3) HS + krmna mešanica 2 (HT2) 
in 4) kontrolni pogoji (19,5 ± 0,9 °C, RV- 85,9 ± 7,3 %) + kon-
trolna krmna mešanica (TC). Telesno maso in zauživanje krme 
smo merili štiri tedne. Po koncu poskusa smo žrtvovali šest ži-
vali iz vsake skupine in vzorčili mišico longissimus lumborum 
za oceno kakovosti mesa. Ugotovili smo, da je v četrtem tednu 
HS negativno vplival na telesno maso prašičev (p < 0,05). HS 
ni statistično značilno vplival na druge parametre, pri čemer 
smo opazili trend izboljšanja teh parametrov ob dodajanju vi-
taminov in mikrorudninskih snovi v krmo prašičev, ki so bili 
izpostavljeni HS. Prašiči, uporabljeni v študiji, so pokazali od-
pornost na škodljive učinke HS na rast in parametre kakovosti 
mesa. Zdi se, da ima vsebnost vitaminov C in E ter mikroru-
dninskih snovi Se in Zn v prehrani prašičev pomembno vlogo 
pri odpornosti na HS, zato je potrebno skrbno oceniti potrebe 
po dodajanju omenjenih dodatkov v krmo prašičev.
Ključne besede: prašiči; prehrana živali; vročinski stres; kr-
mni dodatki; vitamini; mikrominerali; rast; kakovost mesa
Acta agriculturae Slovenica, 118/4 – 20222
A. D. S. V. ORTEGA et al.
1 INTRODUCTION
The ongoing rise in global temperature caused by 
climate change and the ensuing heat stress (HS) intensi-
fication is a severe threat to food security that is expected 
to persist throughout the 21st century (FAO, 2016; Wang 
& Zhang, 2019). Pigs are negatively affected by HS, and it 
was suggested that modern genotypes are more sensitive 
to its negative effects than traditional genotypes (Brown-
Brandl et al., 2001; Brown-Brandl et al., 2004; Renaudeau 
et al., 2011). Pigs under HS focus more on reducing 
metabolic heat production by reducing feed intake by 
up to 23 % per day since they have a low capacity for 
thermoregulation; as a result, production performance 
and product quality are compromised (Renaudeau et al., 
2011; Song et al., 2011; Yang et al., 2014a). Regardless 
of the duration of exposure to high ambient tempera-
ture (AT), pig production parameters such as average 
daily gain (ADG), feed conversion ratio (FCR), and pork 
quality parameters are negatively affected (Song et al., 
2011; Pearce et al., 2013; Morales et al., 2014; Yang et al., 
2014a). Pigs exposed to HS at 30 °C have decreased pH 
value and increased crude fat, drip loss percentage, and 
toughness (Shear Force) of their meat (Yang et al., 2014a; 
Mun et al., 2022). Influence of HS on pigs’ meat pH is 
critical as low pH can increase protein denaturation, re-
sulting in decreased water holding capacity, lighter color, 
and subsequently poor eating quality (Kim et al., 2016; 
Jankowiak et al., 2021).
Such performance depression can also be attrib-
uted to oxidative stress (OS) induced by HS. The bal-
ance between the reactive oxygen species (ROS) and the 
endogenous antioxidant is disturbed by HS. HS causes 
excessive generation of reactive oxygen species (ROS) 
and reduction of endogenous antioxidants, which causes 
the accumulation of dysfunctional proteins, lipid per-
oxidation products, and impaired mitochondrial DNA 
(Slimen et al., 2014; Cui et al., 2019). ROS can induce 
protein modifications upon direct reaction with proteins 
leading to protein oxidation, which leads to higher drip 
loss and toughening of the meat (Huff Lonergan et al., 
2010; Traore et al., 2012). Moreover, OS can reduce col-
lagen synthesis, leading to decreased collagen solubil-
ity and greater meat toughness (Archile-Contreras and 
Purslow, 2011). Therefore, there is a need for mitigation 
strategies to combat detrimental effects of HS. Nutri-
tional intervention strategies using nutritional tools have 
shown progress in abating adverse effects of HS on pig 
performance (Rhoads et al., 2013; Babinszky et al., 2019). 
Exogenous antioxidants, such as vitamins C and E, and 
minerals selenium (Se) and zinc (Zn) can respond to 
such stressors (Traber & Stevens, 2011; Jarosz et al., 2017; 
González de Vega et al., 2018; Kiełczykowska et al., 2018). 
Individual use of vitamins and micro-minerals as supple-
ments in heat-stressed pigs has been studied in the fol-
lowing concentrations: Se (0.5 ppm), vitamin E (100 IU/
kg), Zn (60 mg/kg Zn sulfate + 60 mg/kg Zn amino acid 
complex) (Liu et al., 2016; Mayorga et al., 2018). How-
ever, their effectiveness against negative effects of HS on 
production performance remains unclear. Therefore, the 
present study aims to examine the impact of increased 
concentrations of combination of Zn, Se, vitamin E, and 
vitamin C on growth performance and meat quality of 
pigs under HS conditions. 
2 MATERIALS AND METHODS
2.1 ANIMALS, DIET, AND MANAGEMENT
All experimental procedures were reviewed and 
approved by the University of Debrecen Animal Care 
Committee (Debrecen, Hungary – 9/2019/DEMÁB). 
At the University of Debrecen’s Institute of Agricultural 
Research and Educational Farm’s Animal Husbandry 
Experimental Station (Kismacs, Hungary), a total of 36 
Danbred hybrid barrows (65.1 ± 2.81 kg) were allocated 
to one of the following environmental and dietary treat-
ments (Tables 1, 2 and 3): 1) HS (28.9 ± 0.9 °C, RH- 
60.4 ± 4.3 %) + basal diet (treatment code: HC), 2) HS 
+ diet 1 (treatment code: HT1), 3) HS + diet 2 (treat-
ment code: HT2), and 4) thermo-neutral environment 
(19.5 ± 0.9 °C, RH- 85.9 ± 7.3 %) + control diet (treat-
ment code: TC). All pigs were allowed a 7 day adapta-
tion period to their pens (3 pigs per pen with a total of 
12 pens), fed ad libitum (with control feed) in a thermo-
neutral (TN) environment (average 19.5 ± 1.5 °C). Af-
terwards, the temperature of the HS room was gradually 
raised to 30 °C (heat increment, HI), and pigs in this 
period started receiving different dietary treatments. A 
week after the heat increment, the main period of the 
experiment commenced, which lasted for two weeks. 
Three diets were formulated: the basal or control feed 
(B), formulated on a corn-soybean basis according to the 
(NRC, 2012) recommendation for 75–100 kg live weight 
pigs having 155 g mean protein deposition per day (Ta-
ble 1), and with the nutrient content of the premixture 
added (Table 2). The control diet contained levels of 
vitamins C and E and micro-minerals Zn and Se in ac-
cordance to the NRC recommendation (Table 3). Nutri-
ent recommendation tables do not recommend vitamin 
C supplementation for growing and finishing pigs, but 
in DSM Optimum Vitamin Nutrition (OVN®) guidelines 
(a standard for maximised performance) for breeders 
the recommendation is set at 315 mg/kg of maximum 
supplementation. We choose to add 300 mg/kg for diet 
Acta agriculturae Slovenica, 118/4 – 2022 3
Effects of high vitamin and micro-mineral supplementation on growth performance and pork quality of finishing pigs under heat stress
2 and 150 mg/kg for diet 1. Regarding vitamin E the 
OVN guidelines recommend 64–105 mg/kg, therefore 
we decided for a 30 mg/kg two-step increase of the basal 
diet concentration, resulting in 41 mg/kg in diet 1 and 
71 mg/kg in diet 2. In case of Zn, the maximum al-
lowed supplementation in the EU is 150 mg/kg, there-
fore that was chosen as the maximum value in diet 2, 
whereas concentration in diet 1 was 100 mg/kg, and in 
basal diet 50 mg/kg. Due to toxicity problems complete 
pig feeds should not contain more than 0.5 mg/kg Se in 
total. Therefore, usually not more than 0.2–0.35 mg/kg 
is added to the feed. We decided to increase the NRC 
supplementation of the basal diet (0.16 mg/kg) for 
0.05 mg/kg for two times, resulting in 0.21 mg/kg (diet 1) 
and 0.26 mg/kg (diet 2).
2.2 PRODUCTION PARAMETERS
Each pen had a designated plastic container, of 
which tare-weight was measured and written on the con-
tainer. Weekly feed intake was measured as feed disap-
pearance and feed residues (both from the feeder and the 
container) were measured and recorded. Body weights 
(BW) were obtained weekly from the start of the adapta-
tion period to the end of the experiment. Average daily 
gain (ADG), feed intake (FI), and feed conversion ratio 
(FCR) were calculated weekly, and all represented the 
mean value per pen.
Ingredients Inclusion rate (%) Energy and Nutrients Calculated value
Corn 78.68 Digestible energy, MJ/kg 14.24
Soybean meal 16.33 Crude protein, % 12.81
Plant oil 2.11 SID b Lys, % 0.78
Limestone 0.92 SID Met+Cys, % 0.45
MCP 0.80 SID Thr, % 0.49
L-Lysine 0.30 SID Trp, % 0.14
DL-Methionine 0.01 Ca, % 0.59
L-Tryptophan 0.03 digestible P, % 0.23
L-Threonine 0.06 Na, % 0.10
Salt 0.26
Vitamin and mineral premixture 0.50
Table 1: Composition and calculated nutrient content of basal feeda a
a NRC (2012) recommendation for 75–100 kg live weight pigs having 155 g mean protein deposition per day, b standardized ileal digestible
Nutrient Inclusion rate Concentration
Zn mg/kg 9999
Cu mg/kg 1454
Fe mg/kg 7281
Mn mg/kg 9999
I mg/kg 136
Se mg/kg 32
Vitamin A IU/kg 410000
Vitamin D-3 IU/kg 82000
Vitamin E mg/kg 2205
Vitamin K-3 mg/kg 82
Vitamin B-1 mg/kg 62
Vitamin B-2 mg/kg 205
Ca-d-pantothenate mg/kg 492
Vitamin B-6 mg/kg 164
Vitamin B-12 mg/kg 1
Biotin mg/kg 5
Niacin mg/kg 1026
Folate mg/kg 25
Choline chloride mg/kg 60000
Table 2: Nutrient content of the premixture (in 1 kg of premix-
ture) *
* At or above NRC (2012)
Nutrient Basal feed* Diet 1 Diet 2
Vitamin C 0 150 300
Vitamin E 11 41 71
Zn** 50 100 150
Se** 0.16 0.21 0.26
Table 3: Dietary treatments (supplementation mg/kg)
* NRC (2012); ** organic source
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A. D. S. V. ORTEGA et al.
point at which the sample completely fills the triangu-
lar cavity of the blade and cuts through the sample sur-
face. After this point shearing continues throughout the 
whole sample until the blade has passed through the base 
plate slot. The blade then returns to its starting position. 
Curves were evaluated to get shear force data.
2.3.2 Chemical analysis of the meat samples
Total nitrogen was analyzed using Kjeldahl-Method 
and protein content was calculated using the factor of 
6.25. Fat was measured according to MSZ ISO 1443:2002 
standard. For the elemental analysis (vitamin C and min-
erals) ground meat samples (1.000 g) were loaded into 
digester tubes. To all samples ten ml of distilled conc. 
HNO3 was added and heated at 60 °C for 30 min, then 
3 ml 30%(v/v) H2O2 (Scharlab, Magyarország Kft., De-
brecen, Hungary) was added, and the samples were di-
gested further at 120 °C for 90 mins. After the digestion, 
all samples were washed into 50 ml volumetric flasks 
with distilled water, homogenized, and filtered (MN 640 
W paper; Macherey-Nagel). ICP-OES technique was 
applied on the iCAP 7000 spectrophotometer (Thermo 
Scientific). For the calibration, a multielement standard 
solution was applied. 
2.4 STATISTICAL ANALYSIS
Data were analyzed using GraphPad Prism 7.05 
software (GraphPad Software Incorporated, San Diego, 
USA). One-way ANOVA was used to evaluate the pro-
duction and pork quality parameters. Data were ex-
pressed as mean, and group means differences were 
separated by the Tukey test. Differences among the treat-
ments were considered significant when p < 0.05.
3 RESULTS 
3.1 GROWTH PERFORMANCE
After two weeks of exposure to HS, pigs in HC and 
HT2 groups were significantly lighter (p < 0.05) com-
pared to those in the TC group. Interestingly, pigs in HT1 
had comparable weights to TC (Figure 1e). Duration of 
HS and supplementation of elevated levels of vitamins (C 
and E) and micro-minerals (Zn and Se) did not signifi-
cantly affect the rest of the growth performance param-
eters (Table 4). 
2.3 SLAUGHTER AND PORK QUALITY MEAS-
UREMENT
At the end of the trial, six pigs from each treatment 
(24 pigs in total) were slaughtered. The slaughtering 
comprised of two days where three pigs from each treat-
ment (12 pigs in total per day) were slaughtered in simi-
lar manner after electrical stunning. The pigs for slaugh-
ter were selected randomly. About 500 g of longissimus 
lumborum muscle was removed between the 12th rib and 
5th lumbar vertebrae of the pig carcass for meat quality 
measurements, as described by Rezar et al. (2017).
2.3.1 Physical meat quality assessment
The meat pH was measured at 45 minutes and 24 
hours after slaughter in the loin by Testo AG Germany 
205 pH value gauge (immersed in a buffer solution be-
fore measurement). The meat color was measured using 
Konica Minolta CR-410 Chroma Meter (Konica Minol-
ta Corporation, Japan) 24 hours after slaughter with a 
21-minute blooming time. The Chroma Meter was cali-
brated with the use of a white calibration plate before the 
analysis, setting the Y, x, and y illuminant coordinates 
(Y = 93.7, x = 0.3144, y = 0.3204). Regarding meat color, 
L* (the degree of lightness, on a scale between 0 (black) 
and 100 (white), a* (is red-green), and b* (stands for the 
yellow-blue color characteristic) values represent a color 
space defined by CIE. In the CIELAB system by using 
the measured a*, b*, L* features (a* = red, b* = yellow, 
L* = paleness).
For drip loss (%) determination, one cm thick meat 
pieces of 50 ± 5 g were cut. Pieces were packed in an in-
flated nylon bag, then hung up in the fridge at 4 °C for 
48 hours and weighed again. For freeze loss (%) deter-
mination, from the frozen meat samples (–20 °C), meat 
of 100 ± 5 g and 1 cm thick pieces was cut, stored at 4 °C 
for 24 hours, and weighed. The same samples used for 
thawing loss were cooked. For the evaluation of cooking 
loss, pieces were packed in nylon bags and cooked for 
half an hour until reaching the 75 °C core temperature 
and weighed. After cooking, meat pieces were chilled 
at 4 °C overnight then sliced in cuboids and measured. 
For the firmness, shear force measurement (N) was con-
ducted on cooked samples, with shear blade set using 25 
kg load cell, with 1.5 mm/s test speed from 40 mm dis-
tance, using a Warner-Bratzler shear machine (TA.XT + 
Texture Analyzer 6.1.18.0 version (Texture exponential, 
Stable Microsystems Ltd., Vienna Court, Lammas Road, 
Godalming, Surrey GU7 1YL, United Kingdom)). Once 
the trigger force is attained, the blade proceeds to shear 
through the sample. The maximum force denotes the 
Acta agriculturae Slovenica, 118/4 – 2022 5
Effects of high vitamin and micro-mineral supplementation on growth performance and pork quality of finishing pigs under heat stress
3.2 MEAT QUALITY
As shown in Table 5, chemical and physical analy-
sis of meat samples obtained from pigs kept in TN and 
HC environment fed their respective dietary treatments 
(basal, diet 1, and diet 2) have similar results among all 
experimental treatments (p > 0.05). HS, vitamin C, E, 
and micro-minerals Zn and Se supplementation did not 
significantly affect the meat quality parameters of pigs 
(p > 0.05).
4 DISCUSSION
4.1 GROWTH PERFORMANCE
Several studies reported that high ambient tempera-
ture induced detrimental effects on growing parameters 
of pigs (Kellner et al., 2016; Cervantes et al., 2016; da 
Fonseca de Oliveira et al., 2019). Slow growth, decreased 
feed efficiency, and carcass lean are affected by pigs un-
der such stressors, which are significant contributors 
to economic losses in pig production (Gonzalez-Rivas 
et al., 2020). Mitigation of such adverse effects through 
vitamins and micro-minerals has been reviewed and 
documented (Cotrell et al., 2015); however, information 
regarding the mitigation capacity of their combinations 
is limited. In our study, 14 days of HS caused a signifi-
cant decrease (p < 0.05) in the body weight (BW) of pigs 
fed with basal feed (HC) and diets supplemented with 
higher concentrations of vitamins and micro-minerals 
(HT2). Interestingly, pigs fed diet 1 (HT1) had a com-
parable body weight with those in TN conditions (TC). 
A decline in BW is commonly observed in some animals 
as a response to HS, which can be attributed to the lower 
feed and nutrient intake of such animals exposed to the 
stressor (Xin et al., 2018; Goo et al., 2019). However, the 
reduction in the BW observed in HT2 pigs was unex-
pected. This observation might be due to the decreased 
feed consumption as supported by lower feed intake by 
pigs in HT2 regardless of the supplementation. A simi-
lar observation was reported by Sanz Fernandez et al. 
(2013), where pigs exposed to HS-fed diets containing 
inorganic and organic zinc supplemented at a level of 
120, 100 + 120, and 120 + 200 mg/kg, respectively, had 
comparable performance in terms of feed intake and 
BW. Contrastingly, Romu-Valdez et al. (2019), and Lv 
et al. (2015), reported that high levels of antioxidants 
(organic zinc 360 mg/kg, and selenium-enriched probi-
otics 0.46 mg/kg, respectively) in the diet have positive 
effects on production performance of pigs under HS, as 
supported by improvements in BW, FI, ADG, and FCR. 
Statistically, comparable performance was exhibited by 
pigs in all the treatment groups in terms of ADG, FI, 
and FCR under all periods of observation in our experi-
ment. However, pigs under HS fed basal diet (HC) had 
 Figure 1: Initial body weight (a), body weight after adaptation period (b), body weight after heat increment (c), body weight after 
1st week of the experiment (d), and body weight after 2nd week of the experiment (e). Values are means, with their standard devia-
tion represented by vertical bars; a, b means with common letter are not significantly different (p > 0.05). HC = heat stress + basal 
diet; HT1 = heat stress + diet 1; HT2 = heat stress + diet 2; TC = thermal comfort + basal diet.
Acta agriculturae Slovenica, 118/4 – 20226
A. D. S. V. ORTEGA et al.
the lowest observed values of all the studied parameters. 
At the same time, supplementation of vitamins and mi-
cro-minerals at increased level in the diet 1 (vitamins C 
–150 mg/kg, E – 41 mg/kg, and minerals Se – 0.21 mg/
kg and Zn – 100 mg/kg) mitigated negative effects of HS. 
The proposed level of supplementation might be effec-
tive enough as there are also studies that reported im-
provements in the growth of pigs under HS-fed diets 
containing only a slight increase in dietary antioxidant 
(Zn – 75 mg/kg) supplementation (Mani et al., 2019).
4.2 MEAT QUALITY
Chronic HS can influence the chemical composition 
and physical characteristics of meat, which has been ob-
served in meat obtained and evaluated from various spe-
cies of animals such as broilers, beef cattle, goats, sheep, 
and pigs (Gregory et al., 2010; Weglarz, 2010; Zhang et 
al., 2012; Cruzen et al., 2015; Gonzales-Rivas et al., 2020). 
Pig productivity is affected by HS, and the stressor highly 
affects pork quality attributes. Decrease in lean tissue, in-
crease in carcass fatness and impaired pork quality, such 
as pale soft exudative meat (PSE), manifested by increased 
lightness and yellowness, and decreased redness of meat 
are common adverse effects of HS on pigs’ productive and 
meat quality performance (Sanz Fernandez et al., 2015; 
Kellner et al., 2016; Liu et al., 2021). Moreover, HS induced 
OS can promote protein modifications due to the increase 
of ROS production. This can lead to protein oxidation that 
can decrease the water holding capacity (WHC) of the 
meat and causes its toughness (Huff Lonergan et al., 2010; 
Traore et al., 2012). As reported by Yang et al. (2014b), ex-
posure of pigs to long term HS at 30 °C increased the drip 
loss and shearing force of longissimus muscle. These attrib-
utes are also correlated to HS effect on pork pH (significant 
decrease - 5.43, which is below the optimal pH range of 
5.7–6.1) signifying its importance (Klont, 2005; Yang et al., 
2014b; Jankowiak et al., 2021). Nevertheless, as observed 
in different poultry and livestock animals (broilers, lambs, 
and pigs), vitamins and micro-minerals supplementation 
to the diet can be an effective tool to mitigate detrimental 
effects of HS on meat quality (Shakeri et al., 2019; Silva et 
al., 2019; Chauhan et al., 2020; Liu et al., 2021). Interest-
ingly, the 14-day chronic HS exposure of Danbred hybrid 
pigs in our study did not cause any significant changes in 
the quality of their meat. Supplementation of vitamins 
and micro-minerals did not significantly influence the 
meat quality of pigs exposed to HS. Although our results 
are in contrast to the observations of Yang et al. (2014b) 
(pigs exposed to chronic HS (30 °C)); Shi et al. (2016) (pigs 
exposed to chronic HS (35 °C)); Ma et al. (2019) pigs ex-
posed to chronic HS (35 °C)); and Liu et al. (2021) (pigs 
exposed to chronic HS (35 °C)). But it is in agreement with 
Parameter
Treatment
SEM e p valueHC a HT1 b HT2 c TC d
Average daily gain, g/d
HI f 1536 1626 1383 1375 59.10 0.4031
HS g, 1st week 1598 1721 1483 1850 86.18 0.5311
HS, 2nd week 1119 1421 1357 1700 100.89 0.2537
HS, 2 weeks 1358 1571 1420 1775 65.38 0.0814
Average daily feed intake, g/d
HI 3498 3557 3265 3423 45.44 0.0970
HS, 1st week 3544 3665 3495 3806 86.43 0.6500
HS, 2nd week 3898 3501 4227 3915 114.57 0.1573
HS, 2 weeks 3730 3781 3498 4017 106.83 0.1018
Feed conversion ratio
HI 2.30 2.20 2.41 2.51 0.08 0.5896
HS, 1st week 2.23 2.21 2.42 2.06 0.09 0.7117
HS, 2nd week 3.53 2.95 2.61 2.50 0.17 0.1369
HS, 2 weeks 2.73 2.41 2.51 2.26 0.07 0.0955
Table 4: Growth performance of pigs kept in thermo-neutral and heat-stress environment fed basal diet and diets containing 
increased concentrations of vitamins C and E and microminerals Zn and Se
a heat stress + basal diet; b heat stress + diet 1; c heat stress + diet 2; d thermal comfort + basal diet; e standard error of mean; f heat increment; 
g heat stress
Acta agriculturae Slovenica, 118/4 – 2022 7
Effects of high vitamin and micro-mineral supplementation on growth performance and pork quality of finishing pigs under heat stress
the observations of Lehotayová et al. (2012) in pigs ex-
posed to constant HS (30 °C) throughout the growing and 
finishing period. They concluded that several meat quality 
parameters, such as shear force, drip loss, and meat colour, 
were not significantly affected by HS. The resilience of pigs 
to HS, as observed by the quality of their meat evaluated 
in this study, might be due to their ability to tolerate such 
stressors over time (Campos et al., 2017). Several studies 
reported that a longer duration of HS exposure could re-
sult in gradual performance improvement in pigs. Such 
observation may result from the adaptive changes, such as 
a decrease in heat production during the acclimation stage 
upon chronic exposure to HS (Renaudeau et al., 2008; Re-
naudeau et al., 2010, Renaudeau et al., 2013). Moreover, as 
concluded in the growth performance evaluation no deci-
sive effect of either temperature or diet could be seen, it is 
therefore expected that the meat quality evaluation would 
have similar results.
5 CONCLUSIONS
The pigs used in the study were not severely affected 
by chronic HS. They responded with slightly lower growth 
performance (ADG, ADFI, and FCR) than pigs in TN 
environment and have comparable meat quality charac-
teristics. Supplementation of the diet with vitamins and 
micro-minerals (vitamin C (150 mg/kg) E (41 mg/kg), 
Zn (100 mg/kg) and Se (0.21 mg/kg)) contributed to the 
slight improvement in the growth performance of pigs un-
der chronic HS; however, such supplementation did not 
significantly affect the meat quality of the pigs. Therefore, 
we can conclude that the high ambient temperature chal-
lenge of 14 days has no significant effect on the growth 
performance and meat quality of the pigs used in this 
study. Careful evaluation of vitamin and micro-mineral 
supplementation levels seems important in pigs reared 
under chronic HS conditions since the pigs in the study 
responded with improved growth performance in HT1 
group, but not in HT2 group.
6 ACKNOWLEDGEMENTS
This study was supported by the EFOP 362-16-2017-
00001 project, and the project was financed by the Euro-
pean Union and the European Social Fund. We also thank 
DSM Nutritional Products Hungary Ltd. (Újhartyán, 
Hungary) for providing the vitamin and mineral supple-
ments. Ortega, ADSV appreciates the support of the Tem-
pus Public Foundation, Stipendium Hungaricum Scholar-
ship Programme. 
Parameter
Treatment
SEM e p valueHC a HT1 b HT2 c TC d
Moisture, % 67.87 67.68 68.17 67.45 0.29 0.8636
Protein, % f 22.12 22.85 22.25 22.38 0.22 0.7095
Fat, % f 8.46 7.93 8.04 8.62 0.13 0.1937
Vitamin C, mg/100g f 9.60 8.31 8.40 9.26 0.64 0.8807
Zn, mg/kg f 12.48 11.74 12.30 11.70 0.33 0.8075
Se, mg/kg f 0.3910 0.3385 0.3342 0.3172 0.02 0.6864
pH 45 minutes 6.38 6.44 6.44 6.46 0.04 0.9118
pH 24 hours 5.53 5.53 5.22 5.47 0.01 0.3297
L* (lightness) 51.09 50.87 51.52 49.84 0.38 0.4764
a* (redness) 15.95 16.47 15.88 15.09 0.22 0.1824
b* (yellowness) 4.22 4.17 4.62 3.60 0.15 0.1126
Drip loss, % 2.68 2.96 2.41 2.54 0.15 0.6453
Freeze loss, % 9.58 11.51 12.48 11.25 0.40 0.0764
Cook loss, % 25.10 24.86 24.31 23.60 0.42 0.6370
Firmness, N 53.58 62.83 58.98 55.48 1.83 0.3089
Shear force, N 528.70 587.80 554.30 499.50 16.64 0.2933
Table 5: Meat quality of thermo-neutral and heat-stressed pigs fed basal diet and diets containing increased content of vitamins C 
and E and microminerals Zn and Se
a heat stress + basal diet; b heat stress + diet 1; c heat stress + diet 2; d thermal comfort + basal diet; e standard error of mean; f in dry matter basis 
Acta agriculturae Slovenica, 118/4 – 20228
A. D. S. V. ORTEGA et al.
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