| dc.description.abstract | Two studies were done to assess the influence of feeding
levels of sorghum based diets on reproduction in primiparous sows.
The first study was conducted to asses the effect of replacing
maize w i th sorghum in p i q diets in terms of digestibility of
energy, prote in, fibre. Four di fferent iso-energetic and
iso-nitrogenous diets were formulated to National Research Council
(NRC) specifications and fed to eight finishing pigs (four barrows
and four gilts) in a latin square designed experiment. The first
diet (I) was a maize-soybean control diet. The second (II) was
maize based, the third (III) was based on maize and sorghum in
equal proportions by weight, while the fourth diet (IV) was based
wholly on sorghum. Sunflower and cotton seed cake were the protein
sources in diets II to IV. Dietary energy deficiencies were made up
for by use of lard.
The digestibility coefficients of energy and protein for diets
I to IV ranged from (77 to 82.3%) and (69.5 to 85.9%)
respectively. There was a progressive improvement ln energy and
protein digestibility values with increase of maize ln the diets.
In the second study, 24 gilts were fed low (L) and high (H)
levels of experimental feed (14.2 MJ/kg DE; 14% CP) in gestation.
The low group (L) was given 1 kg of feed per day while the high
group was fed 2.1 kg per day. At farrowing gilts in each level • were redistributed to a low (L) and a high (H) levels of lactation
feed (14.6 MJ/kg DE; 15% CP) during lactation. The low group was
fed 1 kg plus 0.3 kg per piglet in the litter daily and the high
was fed 2.1 kg plus 0.5 kg per piglet. Combinations of feeding
levels in gesta~ion and lactation resulted in high-high (HH) ,-highlow
(HL), low-high (LH) and low-low (LL) levels. Gilt and piglet
weights were recorded weekly. Seven blood samples were taken at 30
minute intervals weekly during lactation from 2 sows in each
gestation-lactation feeding level SUbgroup, centrifuged and plasma
taken for LH assays. Weaning was after a four week lactation when
daily feed allowance was reduced to 2 kg. The sows were slaughtered
28 days post-mating for reproductive system and carcass evaluation
studies. Gilts on the high plane of feeding gained 30.3 kg while
those on low plane ga ined 15.4 kg during gestation. The actual
maternal body weight gain was 15.9 and 2.7 respectively (P < 0.05).
Litter size, average piglet birth weight and conversion efficiency
were unaffected by feeding level (P > 0.05). Over the lactation,
the LL group lost 16kg, LH lost 17.1, HL lost 11.2 and HH lost 1.9
kg (P < 0.05). Litter and piglet weight gain was not affected by
feeding level (P > 0.05) but feed efficiency was higher (P < 0.05)
for the lower level of feeding.
High fed sows came back to oestrus eight days earlier than in
the other three groups. Decreasing level of feeding was
characterised by either prolonged anoestrus or conception failure.
In the subsequent gestation, the gilts were slaughtered 28 days
after mating. The four feeding levels had no carcass measurement
differences at slaughter(P > 0.05). However, sows fed high in
gestation released more ova, had heavier ovaries and placentas,
higher foetal fluid volumes (P < 0.05) but did not differ from low
fed sows in embryo weight (P > 0.05) by slaughter time. Similarly,
sows fed high in lactation released more ova and had heavier
placenta and embryos (P < 0.05). In contrast there was no
difference in foetal fluid volume and ovary and corpora lutea
weights with level of feeding during La ct.at i.on . Increasing feed
intake over gestation and lactation was associated with increased
ovary, placenta and embryo sizes, and higher foetal fluid volumes
(P < 0.5). However, the trend showed that these variations were • more dependent on gestation rather than lactation level of feeding.
The horn of uterus did not influence any embryo developments. Low
fed gilts during gestation had lower plasma levels of luteinizing
hormone during the first week of l2lctation but not thereafter.
It was therefore concluded that the level of feeding during
gestation is important for embryo number and development in the
subsequent reproductive cycle. | en |
