Evaluation of genetic diversity of the Philippine native pigs and socio-cultural perspective of farmers towards conservation management and breeding

概要

報告番号

※

第

主

号

論

文

の

要

旨

Evaluation of genetic diversity of the Philippine native pigs and
socio-cultural perspective of farmers towards conservation

論文題目

management and breeding （フィリピン在来ブタの遺伝的多様性
および保護管理と品種改良に対する農家の社会文化的視点の評価）

氏

名

BANAYO Joy Barraquias

論 文 内 容 の 要 旨
The world animal genetic resource is rapidly declining, which affects the
resilience of livestock and their contribution to food security. Therefore, each
country must act urgently to characterize their animals and determine the
mechanisms for its utilization and conservation. This study was conducted to
characterize the native pigs in the Philippines with the goal of promoting its
utilization in the achievement of national food security. The objectives of this
study were to describe the genetics and morpho logy of the pig and to determine
the production objectives and trait preferences of the farmers to inform
interventions, such as breeding programs and policies. We examined the native
pigs and interviewed the farmers of 7 Philippine provinces, i.e., Bengue t (B),
Kalinga (K), Isabela (I), Nueva Vizcaya (N), Quezon (Q), Marinduque (M), and
Eastern Samar (S). The provinces are further classified by region or island, i.e.,
North Luzon (B, K, I and N, which can be further differentiated as highland B
alone, or lowland K, I and N), South Luzon (Q and M) and Visaya s (S).
Genetic analysis based on the partial mitochondrial DNA D -loop region showed
that the native pigs have Asian wild boar ( Sus scrofa ) origins from multiple
domestication centers, such as East (D2) and Southeast Asia (D7). Furthermore,
we provide evidence of the potential local domestication of the wild boar in North
Luzon highlands giving rise to a group of pigs (primarily from Benguet)
belonging to the Cordillera clade. We identified a total of 19 haplotypes, of which
2 belong to the Cordillera clade. In addition, we show evidence that the native
pigs were not domesticated from the endemic wild pigs of the Philippines, i.e.,

Sus philippensis, S. cebifrons, S. ahoenobarbus, and S. oliveri, as previously

thought. However, interspecific hybridization with wild pigs was observed in
Kalinga, a predominantly indigenous community in the Cordillera region of
North Luzon. Microsatellite analysis s howed that these pigs from Kalinga have
the highest effective population size ( Ne = 420). This result highlights the
advantage of interspecific hybridization in the native pig. In contrast, majority of
the remaining populations have an effective population size below 50, which is a
critical point for short-term viability. Thus, immediate conservation actions are
proposed, such as incentivizing the farming of native pigs to encourage more
farms to utilize this breed and increase its effective population size .
On the other hand, the native pigs in each province showed sufficient genetic
distance (pairwise Fst 0.130 to 0.427) to be considered as distinct populations.
Furthermore, although exotic breeds comprise the majority of pigs in the
Philippines, the native pigs are distinct from transboundary breeds (breeds
found worldwide) Landrace, Large White and Duroc. The genetic distinctiveness
of the native pigs of various provinces poses a challenge in their careful
management, especially with regard to the mainten ance of between-population
genetic diversity, while at the same time maximizing the economic benefit of
heterosis via crossbreeding (with pigs of Cordillera clade or with exotic breeds).
We further evaluated whether native pigs can be discriminated on the basis of
morphology or appearance. Multivariate analysis differentiated the pigs of North
Luzon lowland, South Luzon and Visayan pigs with 84% accuracy. However, the
North

Luzon

highland

pigs

(Benguet)

were

not

physically

discriminated.

Variables that contributed highly to the discrimination were the ratios of tail
length to body length, ear length to body length, and snout length to head length.
On the other hand, clustering analysis showed two groups of pigs, referred as
medium-sized

and

small-sized pigs.

The

grouping did

not correlate

with

geographic origins, suggesting that management may have played a role. The
former has a body weight from 34 to 48 kg while the latter from 13 to 31 kg.
Medium-sized pigs have a body length from 80 to 89 cm, while small-sized pigs
have 56 to 74 cm. In addition to the physical differences of pigs between islands,
their reproductive traits, i.e., teat count (average of 6, on each side) and litter
size (average of n = 7), are moderately variable. We observed a difference of 2
teats (on each side) and about 2 piglets between the highest and the lowest
record. This study shows that the native pig in the Philippines can be
differentiated based on physical parameters which is consistent with their
multiple genetic origins.
We acknowledge that an effective intervention is needed to promote the
widespread utilization of the native pig. Understanding the farmer's preferences

of the breed as well as the challenges they encounter can help inform on these
interventions. Multivariate analysis show the existence of 3 farmer typologies,
i.e., (i) the income-driven farmer (type 3, n = 58) whose production objective is
major income, desire improvement in the growth and reproduction traits of the
native pig, and predominantly male, (ii) the fa rmer who is operating a classic
mixed-farm system of crops, ruminants and poultry (type 2, n = 217), who raise
native pigs for supplemental income, and predominantly female, and (iii) t he
product-oriented farmer (type 1, n = 119) whose production objective is also
supplemental income, but relatively more educated and performs secondary
processing of the meat, also predominantly female. Types 1 and 2 farmers have
more years of farming experience (8 and 12 years, respectively) than type 3 (5
years), thus playing an important role in conservation and genetic improvement.
Recognizing these 3 types of native pig farmers is expected to improve future
interventions, for example, support for intensification on type 3 is recommended.
Majority of the farmers put prior ity on the growth and reproduction traits of
the native pig. Although they showed a willingness to improve their production
system, their production system is generally low input . The current native pig
production system is characterized by a plant-based diet, a lack of vaccinations,
and a lack of marketing efforts. Therefore, to achieve improved growth and
reproduction despite low input production systems we recommend a genetic
intervention, such as increasing feed efficiency as a breeding obj ective for the
Philippine native pig.
This dissertation shows the complex genetics of native pigs in the Philippines
and the multiple types of farmers that raise them. Intervention programs such as
breeding, training and financial support systems must targ et their efforts to the
farmer type appropriate for their purpose. For example, intensification may be
appropriate for income-driven farmers of Nueva Vizcaya, while the establishment
of secondary processing facilities may be appropriate for product -oriented
farmers, and finally, a gender-sensitive support system must be developed for
the female farmers that comprise the majority of the native pig farmers of the
Philippines. The activities recommended should help address the low effective
population size of the native pig and to promote its widespread utilization and
conservation.