Agriculture Reference
In-Depth Information
for gilts with 221 to 240 d of age at first mating compared with gilts mated at younger
or older ages. According to Schukken
et al.
(1994), gilts conceiving at more than 220
days of age corresponded with significantly shorter expected reproductive herd life, but
when combining the effect of litter size and herd life, profit per sow was not significantly
affected by age at first conception.
Hoge and Bates (2011) studied several measures of longevity and lifetime prolificacy
in North American Yorkshire sows and concluded that regardless of the longevity or
lifetime prolificacy definition, a younger age at first farrowing significantly decreased
the risk of culling. Consistently, several studies reported younger age at first farrowing
as a factor increasing survivability (Fernández de Sevilla
et al.
, 2008, 2009a; Holder
et
al.
, 1995; Serenius and Stalder, 2004, 2007; Yazdi
et al.
, 2000a,b). According to Knauer
et al.
(2010), commercial females that are younger at puberty and at first farrowing (i.e.
208 and 353 days of age respectively) have a greater probability of reaching parity four.
On the other hand, Rozeboom
et al.
(1996) did not find an association between age at
first breeding and the ability to complete three parities, or litter size at birth or weaning
in parities one, two, three, or overall. However, the same study reported that increasing
age at first breeding was related to increases in pig birth weights and pig weaning weights
in parities one, two, and overall. In a study conducted on Austrian Large White and
Landrace populations, sows having their first litter before 43 weeks of age or after 60
weeks of age encountered an increased risk of culling (Mészáros
et al.
, 2010).
Nutritional needs for longevity
Nutritional theories that may impact longevity are through mechanisms such as reducing
amino acid intake to reduce the lean to fat ratio and increasing dietary trace minerals
and vitamins that are critical in bone and other tissue development (Kitt, 2010). Mineral
supplementation is vital in the development of the soft and hard tissue structures in the
sow's toes. Calcium is required for normal growth, development and maintenance of the
skeleton where it provides strength and structure. Phosphorus is an essential bone forming
element as it is required for the appropriate mineralization of the skeleton (Crenshaw,
2001). Magnesium contributes to bone strength and integrity and it is also important
in nerve impulse transmission (Patience and Zijlstra, 2001). Micro minerals such as
zinc, copper, and manganese are crucial for a wide variety of physiological processes
in all animals. Copper acts as a growth stimulant when included at pharmacological
concentrations in the diet (125 to 250 mg/kg; Barber
et al.
, 1957). Manganese is essential
for growth and fertility of animals (Underwood and Suttle, 1999) and plays a critical
role in the formation of the organic matrix of the bone. Zinc is required for growth,
development, reproduction and metabolic activity (Hill and Spears, 2001). Deficiencies
in zinc can lead to decreased immune function, lower antibody titers and other deficits
(Richards
et al.
, 2010). Dietary mineral and vitamin deficiencies may be detrimental
to bone, articular cartilage quality and horn quality (Van Riet
et al.,
2013). Animals
fed diets deficient in calcium and phosphorus display lameness, slow gait, paralysis
and spontaneous fractures (Crenshaw, 2001). Signs of manganesium deficiency include
reluctance to stand, weak pasterns and loss of equilibrium (McDowell, 1992). Manganese
deficiency results in skeletal abnormalities, including shorter and thicker front legs,
