Guinea Pig Meat Production: A Systematic Review

Guinea Pig for Meat Production: A Systematic Review

• This article reviews guinea pig meat production, factors affecting their raising, and carcass and meat quality.
• It also includes studies on biological and pathologic effects on carcass component composition.
• Highlights factors affecting carcass and meat quality, like production, environmental, and genetic systems, management, diet, health, age, sex, and reproductive management.

1. Introduction

• Food security is defined as physical, social, and economic access to sufficient safe, nutritious food (FAO, WFP, and IFAD, 2012).
• Guinea pigs are reviewed as a food source and their worldwide distribution as pets or laboratory animals (Dunnum & Salazar-Bravo, 2009).
• Guinea pig farming is growing in developing countries, providing high-quality animal protein, food security, and income (Ngoula et al., 2017).
• This is particularly true in the Andean region and some countries in Asia and Africa (Lammers et al., 2009).
• Guinea pig meat's nutritional characteristics are drawing attention despite limited information.
• Cawthorn and Hoffman (2016) summarized the complexity of eating unconventional animals like guinea pigs.
• Rodents have historically served as food, especially during shortages (Fiedler, 1990).
• Cavies have been a staple meat in the Andes for at least 3000 years (Kyle, 1994).
• While guinea pigs are pets in many countries, most production in Andean countries is for consumption or export.
• Guinea pig meat consumption is marginal compared to chicken, pork, or beef.
• The genetic diversity of guinea pig populations is poorly documented.
• Genetic selection for larger sizes has recently occurred in Peru and Ecuador, resulting in the Tamborada and Auqui breeds (Spotorno et al., 2006).

2. Origin and Uses of Guinea Pig Worldwide

2.1. Historical and Geographic Migration of Guinea Pig

• Guinea pigs, known as “cuy”, “cavy”, or “cobayo”, were domesticated 3000–6000 years ago in the South American highlands and were the first rodent raised for food (Gade, 1967; Lanning, 1967; Wing, 1977).
• Kimura et al. (2016) found that guinea pigs were initially introduced to Puerto Rico from modern-day Colombia based on ancient mitochondrial DNA analysis.
• Phylogenetic research indicates that domestic guinea pigs derived from a single domestication of wild guinea pigs (Cavia tschudii) in the Peruvian highlands over 2500 years ago (Spotorno et al., 2006; Spotorno et al., 2007; Spotorno et al., 2004; Walker et al., 2014; Wing, 1986).

2.2. Multipurpose uses of Guinea pig

• Domestic guinea pigs are multipurpose, serving as pets, laboratory animals, and a meat source.
• They are also used in rituals in the Andean Region and African countries like Nigeria (Onuorah & Ayo, 2003).
• Guinea pigs can produce animal protein at a low cost using feeds, fodders, and vegetal residues.
• Guinea pig meat is considered tasty and low in fat due to their diet of fodders and vegetal residues.
• They are prolific, grow rapidly, reproduce easily, and adapt to various climates and diets (Lammers et al., 2009).
• Guinea pig production is a cheap option to meet protein needs in developing countries.
• Rosenfeld (2008) noted that guinea pigs were crucial in the pre-Columbian Andean diet.
• Guinea pig is now a regional dish for tourists in the Andean Region (Ecuador, Peru, Colombia, and Bolivia).
• Guinea pigs are physiologically and immunologically similar to humans, making them useful as human models in scientific research (Padilla-Carlin et al., 2008).

3. Animal production systems and factors affecting the production

• Guinea pigs are an attractive protein source due to being herbivores that need little concentrated feed.
• They have a voluminous caecum and colon, retaining digesta in the large gut (Sakaguchi et al., 1985; Sakaguchi et al., 1986).
• The caecum contains short-chain fatty acids similar to those in the bovine gastrointestinal tract (Henning & Hird, 1970).
• Guinea pigs lack seasonal breeding habits, allowing for several births per year (Trillmich, 2000).
• 80% of litters are conceived at post-partum oestrus, with a mean gestation of 68 days (Rowling, 1949), resulting in a partum interval of about 70 days.
• Caviomorphs produce precocial offspring that are physiologically mature at birth with open eyes, fully developed fur, and the ability to forage immediately (Michel et al., 2011).
• Most offspring development occurs before birth (Künkele, 2000).
• Neonate guinea pigs can survive weaning at 5 days (Weir, 1974), though weaning after 11 days with an appropriate diet is recommended (Fonteh et al., 2007).
• Factors influencing guinea pig farming include environmental, management, genetic, and health aspects.

3.1. Environmental factors

• Photoperiod does not affect guinea pig reproduction or growth if food and thermal conditions are sufficient (Trillmich, 2000).
• Guenther et al. (2014) found that photoperiod affected somatic and reproductive development in young male Cavia aperea.
• Increased photoperiods led to faster growth in wild male cavies during later development.
• Domestication may have modified this physiological effect in guinea pigs.
• Temperatures of 18 to 25 °C are best for guinea pigs (Ngoula et al., 2017).
• High temperatures (45 °C) increased minor abnormalities and oxidative stress parameters in males.
• Bauer et al. (2008) reported that 16 h of light and 25 °C (LD/25) versus 8 h of light and 15 °C (SD/15) did not affect litter size and pup body weight in the first generation.
• LD/25 males had higher testosterone levels, and short-day conditions retarded puberty in males, but no effect was found in females (Bauer et al., 2008).
• Thermal treatment did not influence reproductive output or offspring characteristics.
• Pregnant females cope with cool temperatures by reducing activity and baseline cortisol levels (Michel et al., 2011).
• The stress response of cool regime females was observed in their offspring, suggesting hormonal influence in utero.

3.2. Management factors

• Chauca (1997) defined three management types:
  • Family management: Animals are kept in or near the house and fed kitchen waste and weeds.
  • Family-commercial management: Animals receive better feed, including concentrated feed, and are sold in city markets.
  • Commercial management: A business activity with improved installations and feed to develop improved meat lines.
  • Another difference is sex separation during fattening; family management raises males and females together, while other systems separate by sex.
• Tenelema Guamán (2016) found no differences in production parameters between guinea pigs raised separated by sex and those that were not, but females got pregnant, reducing carcass yields.
• Adult guinea pigs can maintain body weight and young can grow normally on a cellulose-rich diet (Hirsch, 1973).
  • Guinea pigs may derive more energy from cellulose than other non-ruminants.
• Chiou, Yu & Kuo (2000) found that guinea pigs had better feed conversion rates than rats or hamsters.
  • They also had a significantly longer colon-rectum and higher ability to digest crude fiber compared to rabbits, rats, and hamsters.
  • Guinea pigs have the highest activity of fiber hydrolases in the caecum (Chiou et al., 2000).
• Crowley et al. (2017) reported differences in the microbial population of the digestive tracts between rabbits and guinea pigs.
• Tenelema Guamán (2016) found no difference between using lucerne or agriculture waste in animal growth, but concentrated feed increased slaughter weight.
• Kouakou et al. (2013) found that including Euphorbia heterophylla in the diet increased daily weight gain, liver weight, carcass yield, and lipid content, increased n-3 PUFA content, and decreased n-6/n-3 PUFA content.
• Niba et al. (2004) reported that cottonseed meal can supplement forage-based diets for guinea pigs up to 25% without reducing performance.
• Naturalistic tonic immobility (TI) is an anti-predator behavior produced by fear or stimuli (Lima Rocha et al., 2017).
• Farabollini et al. (1990) showed that the immobility reaction correlated with adrenocorticotropic hormone and beta-endorphin.
• The duration of tonic immobility is positively correlated with basal plasma corticosterone levels (Donatti & Andrade Leite-Panissi, 2011).
• Stress during early to mid-gestation affected the mother–offspring relationship, pup-directed aggressiveness, as well as lowered milk yield (Klaus et al., 2013).
• Apraez-Guerrero et al. (2011) found that castration does not influence growth rate but facilitates handling of males.

3.3. Genetics and health factors

• Studies on guinea pig breeds started in 1966 in Peru.
• A genetic selection program began in 1970 to improve meat production.
• There are two animal groups, “criollo” and “improved” (Chauca, 1997).
  • “Criollo” animals are native, without systematic selection, and have higher disease resistance and less meat yield.
  • “Improved” animals are divided into Perú, Andina, and Inti breeds with better meat yield and adaptation to intensive management.
    • The Peru breed is precocious.
    • The Andina breed is prolific with a higher percentage of postpartum estrus (84%) in the first 5 h.
    • The Inti breed adapts easily to different conditions with a low mortality rate.
• Salmonellosis (Salmonella spp.) is the primary infectious disease.
  • Matsuura et al. (2010) found a 61.5% prevalence of Salmonella enterica in Carhuaz (Peru).
  • Layme et al. (2011) indicated that Salmonella enterica serovar typhimurium is the most frequent serovar isolated in Peru.
  • Contaminated feed is the main path of Salmonella infection (Layme et al., 2011).
• Critical external parasites are Dermanyssus gallinae and Pulex irritans. D. gallinae infestation produces restlessness and mortality in young animals (Florian, 1995).
  • P. irritans infestation reduces body weight during fattening; uninfected animals showed 134 g more body weight than infected animals (Chauca, 1997).

4. Guinea pig carcass evaluation

4.1. Commercial and technical carcass definition

• Until 2016, there were no standard procedures for guinea pig carcass quality or cutting systems.
• Guinea pig carcasses are traditionally presented whole or split into two hemi carcasses and divided into forequarter and hindquarter by cutting between the first and second lumbar vertebra, according to the Peruvian Technical Norm (NTP 201.058, Indecopi, 2006).
• This norm defines the carcass as the body after slaughter and evisceration, including the skin with or without viscera (head, heart, liver, lungs, and kidneys are listed).
• Sánchez-Macías et al. (2016) proposed standard methods for carcass evaluation, jointing, and tissue separation.
  • They defined the carcass as the body after slaughtering, bloodless and scalded, with hair removed, including the head, feet, and viscera.
  • The carcass retains the skin, lateral portions of the diaphragm, and perirenal and pelvic fat deposits.
  • The authors proposed a jointing procedure with four anatomical regions: shoulder, long leg, neck, and ribs and flank.
• Palmay et al. (2015) compared commercial (NTP 201.058, Indecopi, 2006) and standard (Sánchez-Macías et al., 2016) cuts and observed differences due to age and sex in regional and tissue composition when the standard procedure was used.
  
  

4.2. Carcass conformation and fatness classification

• The Peruvian Technical Norm (NTP 201.058, Indecopi, 2006) classifies carcasses by weight, age, body conformation, and fatness, combining two nomenclatures (age/weight and animal conformation).
• This classification can be confusing; for example, carcasses from guinea pigs older than 3 months could weigh less than 800 g or have rectilinear conformation with low perirenal fatness.
• Ara et al. (2012) proposed a 5-rating system for body condition score, described by Sánchez-Macías et al. (2016), well-correlated with body mass index (0.87), total fat (0.83), and dorso-cervical caudal fat (0.86).
• Sánchez-Macías et al. (2016) described a 3-rating system for visual assessment of fat accumulation overlaying the kidneys and pelvic cavity.
• These two rating systems permit a better guinea pig carcass classification.
  
  

4.3. Carcass linear measurements

• Linear body measurements have been used to describe body conformation and carcass composition (Doeschl-Wilson et al., 2005; Maeno et al., 2014), evaluate breed performance (Ozoje & Mbere, 2002), predict live weight gain (Egena & Acheneje, 2010; Chineke et al., 2006), examine relationships between economic characteristics and reproductive performance (Zindove & Chimonyo, 2015), and study heredity and the environment (Zelenák et al., 2004).
• Anye et al. (2010) and Egena and Acheneje (2010) used linear measurements to predict weights.
• Sánchez-Macías et al. (2016) proposed conformation measurements for guinea pig carcasses, including carcass length, hind limb length, thorax and buttocks width, lumbar and thorax circumference, and thorax depth.
• These measurements have been used to predict carcass component composition with high accuracy.

5. Carcass and non-carcass characteristics and factors influencing carcass quality

5.1. Carcass weight and dressing-out percentage

• Carcass quality parameters can be intrinsic or extrinsic (Hocquette et al., 2012), influenced by genetics, pathology, physiology, management, and environment.
• Carcass weight varies from 237 to 893 g, and dressing-out percentages vary from 34.8 to 73.4%.
• The high variation in data is due to different carcass presentations.
• Studies should be done in similar conditions following standard procedures.
• Concentrate, intortum, or supplements inclusion in the diet is important.
  • Chauca (1997) observed increased carcass yield when including concentrate, vitamin C, and water ad libitum.
  • Niba et al. (2004) found that cottonseed cake can be included in supplemental diets up to 25% without significant reduction in growth performance and carcass quality.
  • Tuquinga (2011) and Acosta (2011) found no significant differences in carcass weight or yield using quinoa waste or different commercial concentrates.
• Kouakou et al. (2013) found a 5.8% better carcass yield with dietary supplementation of Euphorbia heterophylla.
• Chauca (1997) reported that improved breeds have higher carcass weights and yields and reach marketing weight four weeks earlier.
• Chauca (1997) and Apraez-Guerrero et al. (2011) found no differences in carcass yields due to castration, but justified it with easier handling.
• Apraez-Guerrero et al. (2011), Hernández (2015), and Remache (2016) found that dressing-out percentage was not affected by sex.
• Carcass yield increases with age (3 to 6 months).
  
  

5.2. Non-carcass components

• There is little information on non-carcass components.
  • Head and feet contribute 11% and 1–1.3% of live weight, respectively (Hernández, 2015; Remache, 2016).
• The liver, lungs, spleen, heart, and kidneys are useful sources of protein, vitamins, and minerals.
• Age and sex differences may cause variations in data.
  • Hernández (2015) reported that 12-month-old guinea pigs had higher offal weights.
  • Remache (2016) reported a progressive development of non-carcass components from 3 to 6 months of age.
  • Lungs, spleen, head, and liver represent a higher proportion in younger guinea pigs.
• Chauca (1997) observed higher weights of non-carcass components in males than females, except for the spleen.
  • Hernández (2015) did not find a sex effect, except that feet were heavier in males in the youngest group, and kidneys were heavier in reproductive males.
    
    

5.3. Carcass composition

• Apraez-Guerrero et al. (2011) found that consumers preferred slaughtered animals to live ones.
  • Guinea pig mortadella and sausages were preferred over beef.
• Sánchez-Macías et al. (2016) cutting procedure showed that the largest cuts are the leg and rib (35–40%), followed by the shoulder (14–17%) and neck (6.5–10.8%) (Palmay et al., 2015; Palacios (2017)).
• Guinea pig carcass composition is 44–48% muscle, 15–20% bone, 5.85–12% dissectible fat, 0.4–1.05% perirenal-fat, 1.4–2.2% remainders, and 18–21% skin (Hernández, 2015).
• At 3 months, female guinea pigs are fatter and contain more bone, but at 12 months, there is no sex difference in carcass composition.
  • Older carcasses have lower muscle and higher fat content.
• Palacios (2017) found that 3 to 6-month-old females have more dissectible fat.
• Bone tissue percentage decreases and fatty tissues increase between 3 and 6 months.
• Carcass components are unevenly distributed among the four cuts (Palmay et al., 2015).
  • Higher dissectible fat is in the neck, followed by the shoulder or ribs.
  • Higher muscle content is in the shoulder, ribs, or hind leg.
  • Bone and skin proportions are similar among cuts.
• Consumers eat a whole cut or half-carcass; therefore, between 5 and 26% of consumption is dissectible fat.

6. Guinea pig meat quality

6.1. Meat proximal composition and fatty acid profile

• Guinea pig meat composition is 73–75.5% moisture, 24.4–26.4% dry matter, 18.8–20.36% protein, 2.7–5.1% fat, and 1.1% ash (Higaonna et al., 2008).
• 18-month-old guinea pigs have more dry matter and fat than 3-month-old animals.
• Chauca (1995) reported 70.6% moisture, 20.3% protein, 7.8% fat, and 0.9% ash.
• Nuwanyakpa et al. (1997) reported 21% protein and 8% fat in West African farm-raised guinea pigs.
• Tandzong et al. (2015) found that meat composition varied by anatomical origin and gender.
  • Females had higher lipid content in the thighs and shoulders.
• Guinea pig meat's protein content is similar to other species, but fat content varies.
• Fat content varies due to sex, age, and genotype.
• Guinea pig meat is high in PUFA, with over 50% of total fatty acids.
• Kouakou et al. (2013) estimated that a guinea pig carcass covers 21% of the daily n-3 PUFA consumption recommended by the National Agency for Food Safety, Environment and Labor of France; considering the skin increases this intake.
• Higaonna et al. (2008) reported that young guinea pig infiltrated fat is higher in polyunsaturated fatty acids than old guinea pigs, while subcutaneous fat of older animals had higher PUFA content (41.8–44.7%).
  
  

6.2. Meat quality

6.2.1. pH evolution and final pH

• Núñez-Valle et al. (2014) determined the postmortem evolution of pH in four muscles.
  • Psoas major and longissimus thoracis et lumborum muscles had the lowest and highest anaerobic capacity, respectively.
  • The pH decreased until 5–6 h, coinciding with rigor mortis.
  • The final pH of the psaos major (6.11–6.27) was higher after 6 h than the other muscles (5.97–6.11).
  • The muscle undergoes a longer period of rigor state, which was resolved after 13 to 15 h post- mortem.
• Stress in guinea pigs could deplete glycogen before slaughter, influencing pH decline.
• Ultimate muscle pH higher than 6 can shorten shelf life (Alonso-Calleja et al., 2004; Gill & Newton, 1979; Magwedere et al., 2013; Shange et al., 2018).
  
  

6.2.2. Shear force value and water holding capacity of Guinea pig meat

• Palacios (2017) found that shear force values increased with age.
  • Tenderness is maintained between 3 and 4 months in males, and 4-month-old females are harder than 3-month-old females.
• Cevallos-Velastegui et al. (2014) compared the water-holding capacity of muscles.
  • Triceps braquii, psoas major, and gracilis had lower values, while gastrocnemio had higher values.
  • Quadriceps femoris had similar values to longissimus thoracis et lumborum.
  • 3-month-old guinea pig meat releases more water than 12-month-old meat.
  • Female guinea pigs lost more water than males at 3 months.
  • Quadriceps femoris muscle could be an alternative for water-holding capacity analysis.
    
    

6.3. Food-borne diseases associated to Guinea pig meat

• Guinea pigs are susceptible to pneumonia, salmonella, parasites, Chagas' disease, and cocciodiosis (Lammers et al., 2009).
• Rodríguez-Lázaro et al. (2015) detected HEV (hepatitis E virus) in illegally imported guinea pig meat.
  • Contamination could occur through zoonotic transmission or manipulation by human handlers.
• Furuoka et al. (2011) performed an experimental transmission of bovine spongiform encephalopathy (BSE) to guinea pigs.
  • Eating infected guinea pigs could transmit this disease.

7. Guinea pig measurements for carcass component, biological and pathologic effects prediction

• Guinea pigs have been used to predict compositional parameters and biological or pathologic effects.
  • Scola et al. (2009) predicted rickettsial skin eschars in humans using an experimental guinea pig model.
  • Ruppert et al. (2016) developed a telemetered guinea pig model for cardiovascular risk assessment.
  • Morissette et al. (2016) used anesthetized guinea pigs to characterize an electromechanical method to predict clinical proarrhythmic potential.
  • Uniyal et al. (2017) found that supplementing 20 ppm Zn nanoparticles had a positive effect on growth rate.
• Studies on carcass and meat quality are limited.
• Barba, Sánchez-Macías, Barba, and Rodríguez (2018) determined the correlation between guinea pig tissue composition and carcass measurements.
  • Combining carcass measurements contributes to predictions of muscle, fat, or bone content.
  • Live and carcass weights showed positive correlation with tissue weights and low correlation in percentages.
    
  • Perirenal fat deposit was strongly positively correlated with dissectible fat.
  • Carcass length, lumbar and thorax circumference were also strongly positively correlated with all carcass components in weight, but not very well-correlated with tissue composition in percentages.
  • The external hind leg length was also well-correlated, but only with muscle, bone and skin tissue weights.
• Barba et al. (2018) presented the prediction of guinea pig carcass tissue composition, using multiple linear regression based on correlation and significance analysis.
  • Carcass weight and thorax circumference were good predictors.
  • Perirenal fat is a very good indicator of carcass fatness (Ara et al., 2012; Barba et al., 2018).
  • The weight of fat can be estimated with live weight, hot carcass, and peri-renal fat weight.
  • Muscle can be estimated with live weight, hot carcass weight, and thorax circumference (R2 of 95%).
    
    
• Sánchez-Macías, Barba-Maggi, Barba-Cuji, and Falconí-Báez (2016) improved the accuracy of the models (from 6.7 to 16.3%) presented by Barba et al. (2018) by including parameters from measurements of a carcass cut of low commercial value, such as the neck.
  • Fat content in the neck was a good predictor of carcass muscle content.
  • Muscle content in the neck is a good predictor of total carcass fat, bone, and skin contents.

8. Conclusions

• Guinea pigs are good meat producers and an alternative source of protein.
• They grow well using food waste, but meat production can increase with concentrate and supplements.
• Dissectible fat varies from 6 to 20% depending on the carcass region, and the fatty acid profile is rich in polyunsaturated fatty acids.
• Guinea pigs are associated with low-income families in the Andean region, Asia, and Africa.
• Due to Salmonella risks, it is not recommended to raise guinea pigs in kitchens.
• More research is needed in meat production systems, carcass and meat quality, animal behavior, welfare, marketing, and social awareness.