Alentejano Pig

The present chapter presents the history and current status of Alentejano pig breed, a Portuguese autochthonous swine breed. A review of literature regarding reproductive and productive traits was carried out. Reproductive performance includes sow age at first parturition and at culling, litters per sow and per year, piglets born alive per litter, percentage of stillborn per litter, piglets birth weight, mortality rate until weaning, piglet weaned per litter, duration of lactation and farrowing interval. Growth performance includes average daily gain and average daily feed intake during lactation, early, middle and late growing stages and fattening stage. Carcass traits were evaluated using age and weight at slaughter, hot carcass weight, carcass yield, lean meat content, back fat thickness at withers and at the level of the last rib, muscle thickness at the cranial edge of gluteus medius muscle and loin eye area. Meat and fat quality traits of longissimus muscle were evaluated by means of pH at 45 min and 24 hours after slaughter, objective colour (CIE L*, a* and b*), intramuscular fat content and fatty acid composition of intramuscular fat. However, a considerable number of studies on Alentejano pig, data on reproductive performance and some parameters of meat quality are still scarce.


History and the current status of the breed (census)
The Alentejano pig belongs to the Mediterranean group [1] and derives, as the Iberian breed pig, from the primitive Sus scrofa mediterraneus. Alentejano pig belongs to the Iberian type breeds, characterized by low prolificacy [2] and low growth rate (except under "montanheira" regime). It is also quite adipogenic [3]. Its meat and fat are considered as excellent for both fresh meat market and to process high-grade sausage and dry cured products. Alentejano pigs are well adapted to the environment and to the use of natural resources as feed. Already in the first century AD, Roman documents stressed out the importance of acorns from holm oak forests and in the outdoor rearing of these pigs from Lusitanos [4]. Before change and domination of indoors pig production system, Alentejano was the main pig breed in Portugal, representing over 45% of the total national pig population [5]. This breed was predominantly distributed by the regions south of the Tagus river. Due to several factors, this breed declined in numbers and importance, mainly since the second half of the twentieth century, and was on the edge of extinction in the 1980s.

Exterior phenotypic characteristics
The information on the morphology of the Alentejano pig is summarized in Table 1. Alentejano is a medium-sized pig with a light bone structure, black coat colour and scarce black, blonde or reddish thin hair (Figures 2 and 3). It has a long, thin head with a pronounced frontonasal angle, and relatively small, thin, forwardfacing ears, triangular in shape and slightly tipped out. The body is not too wide and deep; the back is of medium length and width, slightly arched; the shoulders and hams are regularly developed and medium in width; the extremities are short and slim, ending with small feet with uniform black pigmented hooves. Their temperament is considered energetic [4,9]. Nowadays, the classifications used by the Census of Alentejano pig breed from 1994 to 2017 [8].

Measurement (average) Adult male Adult female
Body weight (kg) 160 120 Body length 2,3 (cm) 126 Ear length Small to medium Small to medium Chest girth 3 (cm) 122 Number of teats 10 1 Data provided by ANCPA (personal communication). 2 Measured from the tip of the nose to the starting point of the tail. 3 Entire males at 120 kg live weight [10]. technicians from the breeders' association vary between placid and friendly to moderately tractable (ANCPA, personal communication), considering the differences found between farms.

Geographical location and production system
This breed's origin and present location is the southwest of the Iberian Peninsula. It is reared under extensive conditions, perfectly adapted to the environment and the use of natural feedstuff resources [7]. It participates into a well-defined agro-sylvo-pastoral system known as "Montado". As a strategic step of this production system, the intensive fattening of animals occurs in Quercus forests from late October to late February ("montanheira") [5].
Traditionally, the herds were divided into three categories: breeding sows, growing pigs and fattening pigs [11]. Breeding sows and growing pigs were fed with natural pastures and, when necessary (e.g., during summer) supplemented with cereal grains (barley, oats or corn), legumes (chickling vetch, faba bean or black chickpea), and local agricultural by-products, which conditioned the growth and duration of the production cycle. Pigs fattened with acorns and grass present very high average daily gains [7,12].  Conversely, nowadays, there is no uniform production system. Breeding season, feeding management, weight and age at slaughter vary among farms, depending on the tradition and the production objectives [7]. However, most production systems usually use two farrowing seasons (spring-summer and fall-winter). Piglets born between April and September go to montanheira the following year. Piglets born between December and March supply the roast piglets' market, the fresh meat market with pigs weighing on average less than 120 kg, and are used for herd replacement when purebred [7,13]. In some cases, alike the observed in Spain with the Iberian pig, in this last farrowing season, a terminal cross with Duroc breed is used to obtain crossbred pigs with better growth performances, higher yields and leaner carcasses (ANCPA, personal communication). The extensive and semi-extensive systems are the most common, and the presence of a free-range feeding period is obligatory for production of PDO and PGI products. However, Alentejano pigs are increasingly reared in semi-extensive systems where, to improve and standardize performance and productivity, most sows and growing pigs receive concentrated balanced feeds. Breeding farms are also abandoning the traditional concrete facilities ("malhadas") and in most cases, farrowing occurs outdoor, in a "camping" environment with huts and/or collective shelters [14].

Organisations for breeding, monitoring and conservation
The Alentejano pig is listed among the endangered Portuguese breeds of farm animals. In 2015, the national legislation (https://dre.pt/web/guest/pe squisa/-/search/66619894/details/maximized) categorized the Alentejano pig breed as in moderate risk of extinction. The names and contacts of the main organizations of the breed are presented in Table 2. The breeding program is run by ACEPA, A.C.E. (Alentejano Pig Complementary Consortium of Companies, A.C.E.), created in 2011, which also holds the Alentejano pig Herdbook. Besides ACEPA, two breeders' associations-the Association of the Alentejano Pig Breeders (ACPA), covering mainly the south of the Alentejo region, and the National Association of the Alentejano Pig Breeders (ANCPA), covering mostly the centre and north of the region-collect data that are stored and processed by the database GenPro (Ruralbit Lda.). More recently (in 2014 and 2017), each association created a Group of Producers (ALPORC SA and PACOOP, CRL) for commercial issues.

Reproductive traits
Despite the availability of commercial artificial insemination doses, in most cases females are naturally mated. At farm level, the ratio of boar:sow varies from 1:5 up to 1:15 (ANCPA, personal communication). Table 3 summarizes the basic data available on the reproductive traits. The mean age of sows at first parturition ranges from 10.6 to 16.6 months, but the gilts management (especially feeding) in each farm can greatly influence this trait, justifying individual variations from 9 up to 24 months of age, at farm level (ANCPA, personal communication). Gestation is shorter than in other breeds or genotypes (111 days [2]). Regarding the litter characteristics, sows of Alentejano breed have a number of live born piglets ranging from 6.7 to 9.4 ([2, [15][16][17][18][19], Charneca R, personal communication), weighing between 1.0 and 1.3 kg at birth [2, 15-17, 20, 21]. The reported stillbirth rate varies between 1.2 and 11.3% [2,15,16]. The high rate on stillbirth in one of the studies [15] may be related to the high total prolificacy also observed in that trial. The reported values for stillbirth rate are lower than the reported in modern genotypes [22]. The mortality rate at weaning mentioned in two studies [2,16] ranged from 18.8 to 27.5%. Both are relatively high values but in line with reported values for other Iberian pigs [23]. The average value for weaned piglets per cycle is 5.7 (ANCPA, personal communication), based on a sample of 2636 records from 20 farms, which is in accordance with the reported values for the prolificacy and mortality rate observed in other scientific studies [2,[15][16][17]. Due to the relatively low growth rate of sucking piglets [2,15,16,18] and usual poor post-weaning conditions, the lactations are usually longer than the practiced in the modern intensive systems, ranging from 35 to 60 days ( [15-17, 20, 21], Charneca R, personal communication). These long lactations increase the farrowing interval and reduce the breed productivity. Regarding the reproductive performance of the Alentejano breed, the information available only covers some data (e.g., number of litters per sow and per year, life production of sow and farrowing interval), representing data collected by the breeders' associations. In the authors' opinion, these data should be used for a clearer monitoring in this breed, after validation. The information available for the Alentejano suggests that this pig breed has a moderate reproductive efficiency.

Growth performance
Basic data available on growth performance of Alentejano pig are presented in Tables 4 and 5. Due to the big differences reported between studies regarding the live weight range covered, the stages for growth performance were defined as lactation (regardless of how long it was), early, middle and late growing stages (from weaning to approximately 30 kg, between 30 and 60, and between 60 and 100 kg live weight, respectively) and fattening stage (above 100 kg live weight). In some sources [17,[24][25][26], only the overall growth rate for the whole studied period (defined as overall) was provided. It should also be noted that only a small number of studies actually aimed at evaluating the breed potential for growth. In the studies mentioned in Table 4, the average daily gain in the lactation period ranged from 133 to 191 g/day. The lactation periods considered varied from 35 to 56 days, and in most cases, piglets were supplemented 15-21 days after birth. Still, all the values are lower than the ones

(2636)
No.-number; mth-month; d-days. 1 Charneca R, unpublished data, University of Évora, 2016. 2 Charneca R, unpublished data from Experimental Centre of Ministry of Agriculture (CEBA), data from 2017. 3 Charneca R, unpublished data from University of Évora experimental farm (Mitra), data from 2012 to 2015. 4 ANCPA, 2018. Breed database values representing data collected from 20 farms computed specifically for this chapter. The number of animals considered for each trait is provided within brackets. Table 3.
Main reproductive traits in Alentejano pig breed.

References
Feeding regime and production system  No, number; ADG, average daily gain in g; w, weaning; Ad Lib, ad libitum feeding regime; Semi, semi ad libitum feeding regime; Rest, restrictive feeding regime. 1 ADG in period of lactation regardless of how long it was. 2 ADG in growing period estimated from weaning to approximately 30 kg, between approximately 30 and 60 kg and between approximately 60 and 100 kg live body weight, respectively. 3 ADG in a period of fattening is reported for above 100 kg live body weight. 4 When the source provides only the overall growth rate for the whole studied period, this growth rate is defined as overall ADG.  No., number; ADFI, average daily feed intake in kg/day; Ad Lib, ad libitum feeding regime; Semi, semi ad libitum feeding regime; Rest, restrictive feeding regime; ME, metabolisable energy; CP, crude protein. 1 ADFI in growing period estimated between approximately 30 and 60 kg (middle) and between approximately 60 and 100 kg live body weight (late), respectively. 2 ADFI in a period of fattening is reported for above 100 kg live body weight. 3 When the source provides only the overall average feed intake for the whole studied period, this feed intake is defined as overall ADFI. Table 5.
Average daily feed intake (in kg/day) in Alentejano pig breed in different studies.
observed in modern breeds [2]. Average daily gain in the early growing stage (192 g/day; [18]) is also considerably lower than those observed in modern breeds [38,39], denoting lesser intensity of rearing and/or growth potential. Also, the middle and late growing stages, the fattening stage, and the overall stage are generally characterized by relatively slow growth and high heterogeneity (251-489, 187-805, 336-1000, and 187-805 g/day in middle and late growing stage, fattening stage, and overall stage [17,18,[24][25][26][27][28][29][30][31][32][33][34][35][36][37]). These differences may be explained by the fact that studies covered distinct situations, where different rearing systems and/or environmental conditions (e.g., season) and also feeding levels were practiced. In the context of the evaluation of growth performance, it is also of interest to observe the extreme values, because it can be assumed that the maximum figures exhibit the growth potential of Alentejano pigs in ad libitum conditions of feeding (≈1000 g/day in the fattening stage [18]). The information on the feed intake and feed nutritional value ( Table 5) is scarce, which limits the evaluation of the breed´growth potential. Nevertheless, as expected, average daily feed intake (ADFI) increased with body weight. In restricted animals, ADFI ranged from 1.6 to 1.7 kg in middle growing stage (from $30 to 60 kg live weight), from 1.9 to 2.9 kg in late growing stage (from 60 to 100 kg live weight) and from 2.5 to 2.7 kg in the fattening stage (>100 kg live weight). The same tendency was observed in ad libitum fed animals even tough values are only available for middle (from 1.5 to 2.0 kg ADFI) and late growing stage (from 2.4 to 3.2 kg ADFI).

Body composition and carcass traits
In Portugal, in most common commercial conditions, Alentejano pigs are slaughtered at weaning for roasted piglet market, at 90-100 kg live weight for the fresh meat market, at 120-140 kg for the production of dry-cured sausages, and at 150-170 kg for the ham industry in Portugal or in Spain [7]. Table 6 summarizes the available information on the most commonly encountered carcass traits obtained from research and field studies. Alentejano breed pigs involved in these studies were slaughtered at ages ranging from 120 to 360 d, and between 39 and 160 kg live weight. Dressing yields and lean meat contents were calculated based on commercial cuts obtained according to the Portuguese norm NP-2931. The backfat thickness at withers ranged from 45 to 78 mm, while at the level of the last rib it varied from 12 to 63 mm. Similarly, muscularity measured as lean meat content varied from 35.9 to 51.7%, the loin eye area from 15 to 32 cm 2 , whereas the muscle thickness measured above Gluteus medius muscle varied from 36 to 43 mm, which indicates lower muscular development compared to modern breeds [39,47,48]. This variation in backfat and muscle thickness is a consequence of the wide range of final live weights of pigs and different feeding regimes applied in the considered studies. Table 7 summarizes the most commonly encountered meat and fat quality traits of Alentejano´carcasses, as measured in Longissimus muscle. In the studies reporting meat quality in Alentejano pigs, pH measured in Longissimus muscle at 45 min post-mortem ranged from 5.89 to 6.45, while at 24 h post mortem it varied between 5.39 and 5.79. These pH 24 values reported in the carcasses of Alentejano pigs are slightly higher than those from modern breeds [52,53], suggesting the existence of lower glycogen stores before slaughter and more 11 Alentejano  No., number; BW, body weight; CW, carcass weight; Ad Lib, ad libitum feeding regime; Semi, semi ad libitum feeding regime; Rest, restrictive feeding regime.

Meat and fat quality
1 M muscle thickness measured according to ZP method (at the cranial edge of Gluteus medius muscle (mm). 2 Groups differ in weight at slaughter; to see more details on study design, address to the corresponding source.  For fatty acid composition, only pigs on control diet were considered. Control diets differ among studies, to see diet composition address to the corresponding source. 3 Groups differ in weight at slaughter; to see more details on study design, address to the corresponding source. Table 7.
Summary of collected literature data on meat quality traits measured in Longissimus muscle from pigs of Alentejano pig breed.
oxidative muscle metabolism. These high pH 24 values are also associated with lower drip loss [54], which corroborates with higher intramuscular fat content (ranging from 3.1 and 7.5%) and darker colour (high Minolta L* value; L* varying from 43 to 51). As previously observed, lower pH values are related with higher water losses by drip due to a reduction in the repulsive electrostatic forces between the myofilaments, partial denaturation of the myosin head (address to [55,56] for review). On the other hand, higher values of intramuscular fat are generally associated to a decrease in the moisture diffusivity coefficient [57]. Intramuscular fat content is highly variable among studies (3.1 and 7.5%; [24, 27, 29, 40-42, 46, 49-51]), mainly due to study conditions (feeding All related legislation and additional information about these products can be found at https://tradicional.dgadr.gov. pt/en/. regime, intensity of rearing, age and body weight at slaughter) but generally increases with body weight at slaughter within specific study (e.g., from 6.2% at 70 kg to 7.5% in 110 kg [40]) and is higher when a restrictive feeding regime is applied. The extreme values obtained for SFA, MUFA and PUFA content of intramuscular fat in Longissimus muscle were 35.0-43.7, 47.7-57.5, and 4.1-10.9% [27,29,33,[49][50][51]. Due to big differences between studies with regard to the feeding regime, feed composition, final body weight/age, and fatness, which are all important factors influencing the fatty acid composition of meat, the results of the fatty acid composition should be interpreted with caution. Nevertheless, it can be concluded that the results reported in the considered studies indicate higher proportions of SFA and particularly of MUFA, in contrast to lower PUFA content, in comparison to the modern meaty type of pigs [27,49,58,59]. This can be attributed to a higher synthesis of MUFA (which increases with age [60]) and SFA, caused by higher fat deposition, as shown by the results of body composition (backfat thickness at the level of the last rib = 40 mm on average, Table 6).

Use of the breed and main products
The Alentejano pig is bred for the production of high-quality meat, sausages and dry-cured products. This slow growing-fat local pig breed is mostly reared in extensive finishing conditions, using the different agro-forest resources at their disposal. The high slaughter ages and weights grants great maturity and better flavour to the meat and meat products obtained, as already recognized in ancient Roman documents [4]. Meat from the Alentejano pig has high contents of oleic acid-rich intramuscular fat, micronutrients and antioxidants [27,61]. It must be produced according to the conditions established in the Portuguese legislation (Decreto-Lei no. 95/2014, 24th of June-MAM, 2014) to be certified under the Protected Designation of Origin ("Carne de Porco Alentejano DOP"). Meat, fat and offal from Alentejano pigs are also used for the production of high-quality products ( Table 8). There are currently five PDO and 23 PGI certified products [62].