Effect of Feeding Frequency on Non-Carcass Components and Wholesale Cuts of Iranian Fat-Tailed Lambs
This experiment was conducted to evaluate the effect of feeding frequency on non-carcass components and wholesale cuts in fat-tailed ram lambs of the Varaminni breed (n = 30, BW = 30.6±3.47 kg). Animals were assigned to three experimental groups according to their initial live body weights in a completely randomized design. The lambs in three groups fed with a TMR ration based on live body weight. First group (control) fed one daily, second group (treatment) fed twice times daily and third treatment fed four times per day. Live body weights recorded at 21 days intervals. Moreover, four lambs from each group were slaughtered and carcass characteristics were measured. Final BW, total BW gain and ADG did not differ (p>0.05). Tail fat content were significantly (p< 0.05) higher in control than those in experimental group. The other carcass characteristics were not significantly different in control with experimental groups. It was concluded that increase of feeding frequency in varaminni ram lambs (fat tailed lambs) resulted in decreased fat reservoirs thus may be beneficial for improving meet production and decrease in fat content of tail.
Feeding ruminants at frequent intervals establishes a reasonably steady-state condition for both digestion and metabolism (Mark and Amos, 1991). Increasing the frequency of meal consumption by ruminants may complement the effect of fiber, associated with its physical form, on ruminal fermentation by maintaining a more constant ruminal Water-Holding Capacity (WHC). Feeding less frequently may shift site of nutrient digestion from the rumen to the hindgut, altering the supply of fermentable substrate to the ruminal microbes and ultimately affecting the protein: energy ratio supplied to the small intestine. These relationships might especially be true when high concentrate diets are fed (Bragg et al., 1986).
The goal of bunk management practices such as programmed feeding, multiple
feed deliveries per day and consistent timing of feed delivery is to reduce
variability in intake (Schwartzkopf-Genswein et al., 2003). Increase
of feeding frequency may improve bioenergetics efficiency and nitrogen retention
in the body (Sutton et al., 1985; Shabi et al., 1999). Feeding
of animals in less frequency increases fat deposition and mobilization. Consequently,
the efficiency of energy retention will be decreased (Sutton et al.,
1986). Robinson and McNiven (1994) showed that feeding cows for seven times
per day instead of two times increased DMI, OM, NDF and crude protein intake.
Moreover, feeding cows for five times daily instead of two times increased DMI
and rumen pH and decreased propionate: acetate ratio in rumen (Robinson and
McQueen, 1994). French and Kennely (1990) showed that increased feeding frequency
improved rumen pH and acetate: propionate ratio, but plasma insulin concentration
tended to decrease. Consuming of easily digestible carbohydrates will decrease
rumen pH and consequently will decrease cellulolytic activity. It can increase
amilolytic activity and consequently increases acetate: propionate ratio in
rumen (Bauman et al., 1971; Kaufmann, 1976). Increased propionate concentration
can stimulate insulin secretion in ruminants (Jenny et al., 1972). Increased
insulin secretion will stimulate glucose and fatty acid absorption and consequently
will increase lipogenesis and reduce lipolysis in adipose tissue. In lactating
cows, insulin usually decreases fatty acid availability for milk fat synthesis
(Foster and McGarry, 2000; Sutton et al., 1988). Therefore, increase
of feeding frequency probably reduces fat synthesis and deposition in different
body tissues. In sheep reported are very low and effect of feeding frequency
on milk fat and tissue component specially fat content are unknown. Church et
al. (1980) reported Increased eating rates have been associated with improved
performance in sheep, Thus, the aim of this study was to investigate the effect
of feeding frequency on body weight and carcass characteristics in Varaminy
growing ram lambs contain fat tail that today fat production in form o tail
is very important problem of animal nutritionist in Iran.
MATERIALS AND METHODS
Animals and location of experiment: Thirty weaned uncastrated ram lambs
of the fat tailed varaminy breed with 5-6 months of age and mean initial BW
of 30.6±3.47 kg were used in the experiment carried out over a 14 week
period between October and January 2004 at the sheep feedlot facility of the
Animal Science Department of Tehran University in Karaj, approximately 45 km
west of Tehran city. The mean maximum temperatures of the area ranged from 20°C
in October to 15°C in January with 250 mm annual rainfall. Lambs were weighed,
ear tagged and treated for external (Azontole, Bayer, Germany) and internal
(Albandazole, VMP Co., Iran) parasites and injected with enterotoxemia vaccine
(Razi Institute, Iran). Lambs were individually housed in concreted floor pens
(1.25x0.8 m) in an environmentally controlled building and were allowed ad
libitum access to feed and water throughout the trial. Lambs were assigned
to three dietary treatments in a completely randomized design. The mean BW gain
and ADG of 30 lambs by the end of trial were 14.1±3.2 kg and 156.6±24.4
g, respectively. The basal diet (Table 1) was formulated for
maximum growth and met or exceeded the requirements recommended by NRC (1985).
The 30 treatments consisted of the basal diet supplemented with one (control),
two, or four time per day. Feed samples were obtained from each batch of feed
mixed for the determination of DM, CP, Ether Extract (EE), ADF, NDF, Ca and
P (AOAC, 1990). At the end of 15 week trial, all of the lambs in each treatment
group were weighed after 16 h of feed deprivation and four lambs from each group
were slaughtered by Iranian traditional procedure (Nik-Khah, 1984) in the department
of Animal Science abattoir. After complete bleeding, the bodies were skinned
and external organs such as head, feet and skin were weighed. The carcasses
were eviscerated and the internal organs or tissues including heart, liver,
kidneys (without fat), lungs, gastrointestinal tract (GIT) and kidney-pelvic-gut
fat was separated and weighed. Wholesale cuts including neck, proximal thoracic
limb, proximal pelvic limb, steak-lumbar, brisket-abdominal region and fat tail
were separated and weighed (Nik-Khah, 1984). The Average Daily Gain (ADG) was
calculated by differences of the initial BW and the slaughter live weight (final
Experimental design: The individual lamb was considered the experimental unit. Least-squares means were reported with pooled standard error. Differences were considered significant at p<0.05. The data were analyzed with the GLM procedures of SAS (1998). Initial BW was used as a covariate in the analysis of the final BW and ADG.
The final BW, total BW gain and ADG were not affected by treatment (Table
2). The head, skin, feet, heart, liver, kidney, empty GIT, lung, heart fat
and internal fat weights were not affected by feeding frequency (p>0.05)
(Table 3). When the two treatments were compared with the
control group, there were no significant differences in the head, feet, liver,
kidney, lung, empty GIT weights (p>0.05), whereas, treatment with two time
per day have higher value in many part of non-carcass component, also Internal
fat weight of lambs fed diets include 2 or 4 time per day were numerically higher
from control and this value in treatment with 4 time per day was highest. Among
carcass wholesale cuts, the weights of proximal thoracic limb, proximal pelvic
limb, neck, steak-lumbar and brisket-abdominal region were not affected by feeding
frequency (p>0.05), where the weights of fat tail decreased by addition of
feeding frequency (p<0.05) (Table 4).
|| Effect of feeding frequency on final BW, total BW gain and
Average Daily Gain (ADG) in fat-tailed lambs
|| Effect of feeding frequency on non-carcass components in
|a: Internal Fat = Kidney-pelvic-gut fat, b:
Empty gastrointestinal tract, *NS: p>0.05
|| Effect of feeding frequency on wholesale cuts in fat-tailed
|a,b: The means in rows with different superscripts
are significantly different, *NS: p>0.10
In the present study, increase of feeding frequency did not affect final BW,
total BW gain and ADG. It is commonly assumed that fluctuations in intake can
cause acidosis and reduce mean DMI and this reduce were affected ADG (Britton
and Stock, 1987). However, in the present study body weight changes were not
significantly different in both experimental groups, where the ratios of some
carcass components is were relatively higher in treatment group than those in
control group. Increase in feeding frequency decreased fat deposition in tail
of varaminni ram lambs. Moreover, internal fat content were not differ with
increased feeding frequency that this occur was inversed with other research
(Sutton et al., 1985; Shabi et al., 1999). Shabi et al.
(1999) has been suggested that increase of feeding frequency would decrease
fat synthesis and deposition in body. In Iranian tail fat lamb that tail is
main store of fat, increased feeding frequency were decreased fat content of
this part but feeding frequency has not affected on internal fat. Sutton et
al. (1986 and 1988) and French and Kennely (1990) in three separated studies,
observed that feeding of dairy cows 6 times per day instead of 2 times decreased
plasma insulin concentration but increased GH and glucose concentrations. They
suggested that it was due to decreased rumen propionate concentration. Considering
the important role of insulin in lipogenesis and reducing lipolysis and stimulatory
effect of GH on lipolipogenesis and protein accretion (Foster and McGarry, 2000)
it is concluded that increasing of feeding frequency can decrease fat synthesis
and deposition. It seems in tailed sheep this effect influence the fat content
in tail and do not influence the internal fat deposition. Moreover this decrease
in fat tail influence other tissue such as wholesale cuts that in this study
numerically was increased.
Implication: Fat production specially in sheep carcass in form of tail in Iranian sheep is very high, thus different method such as genetically, physiological and nutritional method applied for decrease fat contain of carcass. One of nutritional method for increase protein and decrease fat is bunk management Increase of feeding frequency in this lambs led to decreased tail fat. Hence. We emphasis that with increased feeding frequency, carcass fat (in tail) content of sheep is mediated.
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