Livestock plays an important role in the economy of Pakistan. It accounts for about 37% of the agriculture GDP and about 9% of the total GDP. This sector earned over 9% of the overall export in 1998-99(Economic Survey, 2000).
Pakistan like other developing countries in Asia is densely populated. The present growth in population indicates that the magnitude of imbalance between the demand and supply of animal protein will become wider in the years to come. The demand for meat, milk and dairy products is rising day by day. The performance of farm animals mainly depends upon its genetic makeup and the feed, which they consume. The animal of even outstanding genotype cannot show its potentials unless it is properly fed.
The major feed resources available in Pakistan for livestock feeding are green roughages, dry roughages and agro industrial by products. The type, availability and ways of utilization of these feed sources vary greatly in different seasons and parts of the country. One of the main reasons for low productivity of livestock is inadequate nutrition. Poor quality feeds due to deficiency of different nutrients cannot meet the requirements of the animals and are often supplemented with protein and energy to increase the productivity of animals. Oil cakes and cereals bran are the conventional concentrates commonly used. However, these supplements are expensive and cannot be offered by the farmers to their livestock at required levels. There are some cheaper agro industrial by products like sugar beet pulp, which can efficiently replace the most expensive cereal grains and their byproducts in conventional concentrate mixtures. Such agro industrial by products if efficiently utilized can fill a part of the existing nutrients gap for livestock.
Sugar beet pulp is a byproduct of sugar industry. Annual production of wet sugar beet pulp in NWFP is about 81 thousands tons (Habib et al.,2003). Fresh beet pulp contains a large quantity of water and can be fed to livestock as such. Alternatively it can be stored for later use either by silage making or drying. Dry beet pulp is a bulky palatable feedstuff and can be used as substitute for cereal grains in livestock rations. The purpose of the present study was to examine the on farm feasibility of feeding dry beet pulp based concentrate as substitute of conventional concentrate in growing goat kids.
MATERIALS AND METHODS
A growth trial with goat kids was conducted at the livestock research and development Farm (LRDF) Surezai, Peshawar. Experimental samples were analyzed at the animal nutrition laboratory, NWFP Agricultural University Peshawar.
Experimental design and animals: The experiment was conducted in a complete randomized design (CRD). Twenty seven beetle goat kids of 3-4 months were distributed in 9 equal groups (three animals /group) on the basis of bodyweight. They were ear tagged and provided with neck straps of nine different colors for group identification. These groups were randomly allotted to pens of uniform dimensions located in a semi open, well–ventilated shed. Each group represented an experimental unit and was randomly assigned to one of the three experimental diets. Thus each diet was replicated over three groups. One week prior to the commencement of the trial, all the kids were treated against endo- and ecto- parasites. The experiment lasted for 70 days including an adaptation period of 10 days.
Diet and feeding: All the kids were grazed for 3-4 hours daily in the fallow land of agricultural fields with natural vegetation, at the LRDF Surezai. On return to respective pens, after grazing, they were offered the following three diets;
Diet A: Chopped oat hay ad libitum (Control diet).
Diet B: Chopped oat hay ad libitum and 750 g DM/group/day Commercial concentrate (PARC Cattle Feed, 18-20% crude protein)
Diet C: Chopped oat hay ad libitum and 750 g DM /group/day Test concentrate (18-20% crude protein).
The test concentrate was composed of dried sugar beet pulp(50%), molasses(13%), cotton seed meal(6%), cottonseed cake(17%), maize oil cake(8%), urea(8%) and minerals. Wet sugar beet pulp was purchased from Khazana Sugar Mill, Peshawar and dried in open under the sun. The other ingredients were purchased from local market. Mixing of ingredients was done in a power driven mixer. All the groups were offered chopped oat hay ad libitum daily after they consumed the concentrates. Clean drinking water was offered three times daily. The quantity of oat hay and concentrates refused by the kids were weighed daily to estimate feed consumption. Representatives samples of feed offered and refuses and also of the grazing vegetation were collected once a week and stored at -10 OC for chemical analysis. Feed ingredients of the test concentrate were also analyzed for nutrient composition before formulation of the mixture.
Nutrient analysis and degradibility: All the samples were analyzed for dry matter, ash, crude protein (CP) Crude Fiber(CF) and ether extract according to the standard procedure of AOAC(1990). The In-sacco DM Degradability (ISDMD) and CP degradability (ICPD) of the feed samples were determined using the Dacron bag techniques (Orskov et al.,1980). Total digestible nutrients (TDN) values of feed were estimated using the equations suggested by Choo(1982). The TDN values were used for estimation of digestible energy (DE) and metabolizable energy (ME) according to the equations reported by NRC (1985).
Feed intake: The daily dry matter intake of oat hay and concentrates was calculated for each replicate group by subtracting the quantity of feed refused from the quantity of feed offered. For this purpose samples of offered and refused oat hay and concentrate were collected at weekly intervals and analyzed for DM contents as described earlier.
Body weight gain, FCR and feed cost: For calculating body weight gains, all the goat kids were weighed for three consecutive days at the beginning and again at the end of the experiment. Weights of the kids were also regularly recorded at fortnight intervals through out the experimental period for monitoring changes in the body weight and calculating growth rates. At all times, the kids were weighed early in the morning before grazing using an electric digital weighing scale. Feed conversion ratio (FCR) was calculated as the quantity of feed (DM) consumed per unit of body weight gain for each experimental unit. The cost of three experimental diets was determined according to the prevailing rates in the local market. Feed cost (Rs) incurred on per unit (kg) of body weight gain and the net return over feed cost were calculated for the three diets.
Statistics: The data were analyzed with the Analysis of Variance procedure according to CRD(Steel & Torrie, 1981). The means were compared for significance of difference with the LSD procedure (Steel and Torrie, 1981). The General Linear Model (GLM) procedure of SAS (2000) was used for statistical analysis of the data.
RESULTS AND DISCUSSION
Nutrient composition and dry matter degradability:
Nutrient concentrations of the basal diet (oat hay and grasses) and of the two concentrate supplements is given Table-1. Composition of the ingredients used in preparation of the beet pulp concentrate is also reported in Table-1. The proportion of different ingredients along with availability of nutrients from each ingredient in the final mixture of beet pulp based concentrate is summarized in Table-2
Oat hay was of medium quality and had crude protein 9.11% in DM , crude fiber 32.83% in DM and metabolizable energy 1.79 Mcal/Kg on DM basis (Table-1). Similar composition of oat hay was reported earlier by Stanton,(1999). Surprisingly, the grasses grazed by the experimental animals were of superior quality as suggested by its high crude protein content (15.76% in DM), low crude fiber (19.11% in DM and high metabolizable enery (ME) concentration of 2.07Mcal /Kg DM (table-1). The grasses mainly consisted Cynodon dactylon, Panicum antidotal and Cenchrus ciliaris. These were not cultivated but existed as natural/ wild stand near water channels where the kids
were daily grazed. Average growth rate of 27.33g/day/kid in un-supplemental control group(Table-3) suggested that the basal diet of oat hay and grazing due to their good quality supported nutrients requirements of the kids over and above that of maintenance. Both commercial concentrate and beet pulp based concentrate mixtures were close in their nutrient composition (Table-1). Crude protein (CP) and ME concentrations were 19.78, 20.31% in DM and 2.41,2.43 Mcal /kg DM in the above two concentrates, respectively. Crude fiber in the beet pulp based concentrate was higher than the commercial concentrate (21.48 Vs 16.11% DM). This was due to inclusion of large quantity of dried beet pulp (50%) in the concentrate mixture. Nevertheless, Bhattacharya and Sleiman (1975) reported that fiber in beet pulp due to low lignifications was highly digestible. These authors reported that fiber digestibility in beet pulp was higher than 70%. No special concentrate mixture for goats or sheep was available in the local market. Consequently, the dairy concentrate mixture manufactured by PARC, Islamabad was used. NRC (1985) recommended dietary concentrations of CP and ME for goats as 13% in DM and 2.0 Mcal/kg DM, respectively. In the present experiment the diet composition qualified this criterion and mean calculated concentration of CP was 17.4% in DM and ME was 2.3 M cal/kg DM. Thus it could be argued that in the present study quality of both the basal diet and concentrate mixture matched the nutrient requirement of the kids recommended by NRC (1985).
Table 1. Nutrient composition of feeds used in the experiment.
Table 2. Composition of beet pulp concentrate mixture on dry matter basis.
Table 3. Comparative cost of feeding the three experimental diets to growing goat kids.
In sacco degradability:
The in Saccodegradability of DM and CP at 12 hour and 24 hour incubation was measured in both the concentrate mixtures. The results are illustrated in Figure 1. Although DM degradability at both 12 and 24 hours was lower (P<0.05) in the beet pulp concentrate, its protein degradability was consistently higher (P<0.05) than the commercial concentrate. The higher degradability of protein in the beet pulp concentrate was due to inclusion of 1% urea (Table 1). Nevertheless, protein degradability in both the concentrate mixtures was appreciably high and remained above 70%. Maximum protein degradability at 12 hour in both the concentrates that did not increase further with prolonged incubation of 24 hour indicated high fermentation rate of protein. Degradability of protein at 12 and 24 hours incubation in commercial concentrate was 84.90 and 84.98 % and in the beet pulp concentrate was 94.82 and 94.98%, respectively. These results suggested that both the concentrate mixtures were equally efficient in providing soluble nitrogen for microbial activity in the rumen of the experimental animals.
The pattern of daily intake of hay DM and hay plus concentrate DM of the three treatment groups during different weeks of the experiment is depicted in Figures 2 and 3. Data on the intake of total DM including grazing could not be recorded due to difficulties in measuring the intake from grazing land. The DM intake of hay and hay plus concentrate significantly varied due to diets (PM0.0001) and weeks (P<0.0001) and revealed a significant interaction of diet X weeks (P<0.01) in both cases. Since fixed and equal quantity of concentrate in diets B and C was offered to the kids that were consumed in full, it will be more meaningful to compare the consumption of hay among the three treatment groups. This will also explain the effect of the two concentrates on hay consumption.
Among the three treatments groups hay DMI was consistently higher (P<0.01) in control groups and remained the same (P>0.05) between the other two groups given concentrate supplements (Diets B & C). Hay DMI across the experimental period of 8 weeks averaged 319.40, 215.74 and 206.04 g/d on diets, A, B and C respectively. The depression in hay intake in response to concentrate feeding ranged from 32.4 to 35.5%. This clearly suggested substitution effect of concentrate on the intake of basal diet. The present findings agree with the result reported by Habib (1993) who found that addition of concentrate correspondingly decreased the consumption of basal diet of hay. However, Preston and Leng (1987) suggested that a good concentrate should not cause substitution effect when given along with forages. These authors further reported that substitution effect of concentrate supplement depend on composition of the supplement and quality of the basal diet. Feed intake is directly related to digestibility (Van Soest, 1982). In the present study oat hay had an optimum level of CP (6.11% in DM) that together with access of the kids to good quality grazing grasses containing CP 15.7% in DM, may have supported efficient rumen fermentation. Therefore, supplementary feeding of concentrate was presumably not effective in further stimulating the fermentable digestion for increased feed intake. Nevertheless, in the light of Sanson (1993) findings, it was expected that beet pulp based concentrate would increase the intake of oat hay. The author reported that beet pulp contain easily digestible cellulose which stimulate fibrolylic activity in the rumen. No clue for such effect was observed in the present study. As explained earlier, access of the kids to high quality grazing grasses may have confounded such effect of beet pulp feeding.
The intake pattern in Figure 2, illustrate that daily consumption of hay in all the three diets progressively increased (P<0.0001) with the advancement of experimental period. Regression analysis suggested that hay DM intake increased by 34.13, 19.09 and 17.99 g/d with advancement of each one week period on diet, A, B and C respectively.
Body weight gain:
Changes in the Body weight (BWT) of kids in response to the diets over the entire period of 60 days were calculated by two methods Viz; difference of initial and final weights and through regression analysis of BWT against the time (fortnight intervals) of recording weight of the animals. There was no difference (P>0.05) in BWT gain calculated with the two methods and both the methods are, therefore, considered equally reliable in estimating BWT changes. These observations agree with Hameed (2003) who also reported same body weight gain in calves with the two methods.
Body weight gain was influenced by diets (P<0.001) and averaged 27.33, 84.19 and 73.92 g/d on diet A, B and C, respectively. Comparison of the mean revealed that BWT gain on control diet was lowest (P<0.05) than the other two diets. The difference in BWT gain between diets B and C was statistically not significant (P>0.05), suggesting that beet pulp based concentrate was equally effective to commercial concentrate in supporting growth rate in the kids. Changes in the net BWT of the animals on the three diets with advancement of experimental period is illustrated in Figure 4. The BWT curve of control group that changed slightly over time suggested slow growth pattern in the control kids. On the other hand BWT linearly increased with time on diets B and C that demonstrated rapid growth rate in the kids on these two supplemented diets. However, the body weight curves on both concentrate-supplemented diets were parallel and exhibited almost the same slopes. These observations are in close agreement with the mean result of BWT gain (g/d) reported in Table 3.
In the present study growth rates in the kids were increased by 65% in response to concentrate feeding, irrespective of concentrate type. The extra gain of 50-60 g/day resulted with concentrate supplements was due to extra protein and energy supplied by the supplements. Both concentrate mixtures had identical CP levels that ranged from 19.78 to 20.31% in DM and the same metabolizable energy concentrations of 2.41 to 2.43 Mcal/kg DM. The energy protein ratio of 8.21 and 8.35 in diets B and C explain the lack of difference in growth performance of the kids given the two supplements. On diets B and C, the average quantity of concentrate 250 gm DM consumed daily by each kid supplied 50 gm CP and 0.61 Mcal ME per day. These additional nutrients from the two supplements, supported 52 gm extra weight gain in the kids. These observations are in close agreement with NRC (1985) that reported standard requirement of 40g CP and 0.50 Mcal ME for a BWT gain of 50g/day in growing.
Feed conversion ratio and feed cost:
Feed Conversion Ratio (FCR) was calculated as the quanity of DM consumed per unit of BWT gain (DM intake /gain ) and explain the efficiency of feed utilization for growth . The results of FCR are presented in Figure 5. Mean FCR on diets A, B and C were 26.81, 10.75 and 12.97, respectively and they were significantly influenced ((P<0.05 by diet composition. The difference in FCR explain that on diet A, relatively more feed DM, almost 2.5 times greater than the other two diets, was required to support per unit growth rate in the kids. Both concentrate supplemented diets (diet B and C) exhibited the same FCR (P>0.05) and is in accordance to the lack of difference between the two diets recorded for other parameters i.e feed intake and growth rate. In consensus with the literature (Cottyn et al.1976) it can be argued that positive response in FCR on diets B and C was related to improved protein /energy ratios in the diets, consumed by the animals. The protein /energy ratios on diet A, B and C, were calculated as 51, 77 and 78, respectively. The comparison of FCR and protein/energy ration on the three diets is illustrated in Figure 5.
Relative cost of feeding the three experimental diets to kids is given in Table 3. Both supplemental diets (diets B and C) resulted in higher return of Rs. 146 and 129/kid, respectively, than that obtained on control diet (Rs. 51/kid) during the period of 60 days. Although cost per kg BWT (Rs. 25/-) was the same on both supplemental diets, the total return was slightly less with the test concentrate. Nevertheless, in the light of statistical inference that revealed same weight gain on both the diets it can be concluded that both concentrate were equally cost effective under the condition of the present study.
Nutritive value of beet pulp based concentrate and commercial concentrate (PARC cattle feed) was found the same and that the two concentrate mixtures are equally cost effective in supporting growth rate in goat kids. The overall results demonstrated feasibility of using dried beet pulp as a major ingredient in compound feed for goat kids. It is, therefore, recommended that drying of wet beet pulp on commercial scale and its incorporation in compound feed for ruminants should be undertaken in areas like NWFP to ensure efficient utilization of this valuable feed for increasing milk and meat production. Moreover, research is needed to explore the substitution of conventional concentrate mixtures with beet pulp-based concentrate mixture in dairy and fattening rations for ruminant livestock.
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