The effect of supplementing Rhodes grass hay with cotton seed cake and pyrethrum marc based rations on the performance of Sahiwal female weaners

F W Wekesa, S A Abdulrazak* and E A Mukisira**

National Animal Husbandry Research Centre, P.O Box 25 Naivasha. Kenya.
*Division of Research and Extension, Egerton University, P.O Box 536, Njoro. Kenya
**Kenya Agricultural Research Institute, P.O Box 57811, Nairobi. Kenya
sabdulrazak@yahoo.com

Abstract

The objective of the study was to evaluate the voluntary feed intake and body weight gain of Sahiwal female weaners fed on rhodes grass hay and supplemented with cotton seed cake based ration (CSCBR) and pyrethrum marc based ration (PMBR). Twenty five weaners were allocated to five treatments in a randomised complete design (RCD).

The CP contents of the feeds were 74.1, 156 and 143 g/kg dry matter (DM) and neutral detergent fibre (NDF) was 720, 345 and 329 g/kg DM for Rhodes grass hay (RGH), CSBR and PMBR respectively. At higher level of supplementation, improved dry matter intake was recorded in the group that was offered PMBR than CSCBR. Supplementation also improved dry matter intake with hardly any substitution effect. Better average daily gain was recorded in weaners, which were supplemented with CSCBR but was not statistically different from the PMBR while control group grew at the lowest rate. Volatile fatty acid concentration improved with supplementation but varied across the treatment diets. All the animals across the various treatment diets remained in a positive nitrogen balance during the period of study. Supplementation also improved rumen ammonia nitrogen levels.

It was concluded that CSCBR and PMBR were comparable in respect of animal performance and hence be encouraged in their inclusion in ruminant rations.

Key words: Cotton seed cake, intake, live-weight gain, pyrethrum marc, Rhodes grass hay

Introduction

In many parts of the tropics, the abundant feed resources such as natural pasture and crop residues are characterized by inadequacy of essential nutrients particularly in the dry season. Deficiency of nutrients in diets of ruminants fed low quality forage constrain animal performance and hence the necessity for interventions to correct these deficiencies. Most of the deficiencies can be corrected by supplementation (Siebert and Hunter 1982). Correcting dietary deficiencies can have two effects in ruminants, which includes increasing microbial degradation of feeds in the rumen and improving the animals' metabolic capacity to use energy both of which increase voluntary intake, digestible organic matter and animal performance. It is against this background that feed ingredients comprising of cotton seed cake, pyrethrum marc, poultry litter and maize germ and minerals were used to formulate two rations namely "cotton seed cake" (CSBR) and "pyrethrum marc" (PMBR) supplements for Sahiwal female weaners fed on a basal diet of Rhodes grass hay.

Pyrethrum marc is increasingly being used as a livestock feed in Kenya particularly in the dry season. This is mainly because pyrethrum marc is cheap and available, as Kenya is the leading producer of pyrethrum. Pyrethrum marc has been reported to control sheep gastrointestinal nematodes (Mbaria et al 1988). Partial substitution of maize silage up to 50% with pyrethrum marc in beef cattle feedlots produced better average carcass grades than similar rations without pyrethrum marc (Griffin 1974) while inclusion of pyrethrum marc as a supplementary feed to a basal diet of hay in sheep improved dry matter intake and digestibility of those diets (Thomas 1975). Poultry litter from cages and deep litter system has substantial nutritional value for feeding ruminants as it is rich in non-protein protein and other nutrients, which are very essential for providing nitrogen supply for rumen microbes and conducive environment for microbial activity (Paul et al 1993). Poultry litter supplementation improved dry matter intake of Friesian steers fed on a basal diet of Napier grass (Muia 2000). Poultry litter is also available on-farm to most farmers and hence cheap. Cotton seed cake on the other hand was used because it is good quality as it is known to have by-pass protein attributes which are efficiently utilized by the animals. The objective of the study was to evaluate voluntary feed intake and body weight gain of Sahiwal female weaners when supplemented with CSCBR and PMBR as it was hypothesized that these rations would improve animal performance.

Materials and Methods

The study was conducted at Kenya Agricultural Research Institute's (KARI) National Animal Husbandry Research Centre (NAHRC) at Naivasha, Kenya, which is situated at an altitude of 1890 m above sea level. The annual rainfall is 620 mm and a mean annual temperature of 18 ^o C.

Twenty five Sahiwal female weaners (Bos indicus) with initial mean live weight of 81 kg (± 15.1) and age of 288 days (±48.2) were used in the study. Before being brought in the stables (zero grazing unit) the weaners were previously extensively grazed on natural pasture, which consisted mainly of Naivasha star grass (Cynodon plectostachys) without any supplementation. At the start of the trial, the animals were drenched with an anthelmintic (Nilzan plus®) The animals were dipped weekly as a control measure against tick infestation. Weaners were weighed for three consecutive days weekly using an electronic weighbridge for 8 weeks. Weekly live weight changes were recorded to estimate average daily gains (ADG).

In the digestibility experiment, fifteen doper rams with an initial average live weight of 53 kg (±7.82) and 24.5 months (±12.6) old were used. The rams were treated against internal parasites and confined in metabolic cages fitted with provisions for forage, water and supplements. The animals were used for studies in which digestibility; rumen pH, NH₃-N and Volatile fatty acids were determined. In rumen degradation studies, two fistulated Friesian steers with an average body weight of 400 kg were used. The animals were confined in well ventilated individual cubicles and provided with ad libitum Rhodes grass hay supplemented with 1 kg of dairy meal each plus minerals daily.

Rhodes grass hay (Chloris gayana) (RGH), which was a basal diet, was cut into pieces measuring between 2.5 to 3.0 cm in an effort to minimize both wastage and preferential selection. Feed ingredients used in ration formulation included maize germ, poultry litter, cotton seed cake and pyrethrum marc all of which except poultry litter were purchased from local commercial feed manufacturers. The litter was sieved and sun dried for three consecutive days and subsequently put in gunny bags and stored. Two concentrates were formulated, namely cotton Seed Cake Based ration (CSCBR) (Maize germ 35%, Poultry litter 48%, Cotton seed cake 15%, Minerals (2%) and Pyrethrum marc Based Rations (PMBR) (Maize germ 15%, Poultry litter 65%, Pyrethrum marc 15%,  Minerals 2%.

The experimental design was a complete randomised design. The sahiwal weaners were divided into five groups of five animals each based on live weight and age and randomly allocated to five diets, which included the following:

• RGH: Rhodes grass hay + minerals (control)

• 0.5CSCBR; RGH + 0.5 kg/d CSBR;

• 1.0CSBR: RGH + 1 kg/d  CSCBR;

• 0.5PMBR: RGH + 0.5 kg/d PMBR

• 1.0PMBR: RGH 1 kg/d  PMBR.

Rhodes grass hay was offered ad libitum into two equal halves in the morning (08.00 h) and in the afternoon (14.00 h). However, supplements were all offered in morning feeding. The adaptation period was 14 days while data collection took 56 days. Weighing of weaners was done using an electronic weighbridge before feeding. The daily feed on offer was estimated using the previous day's intake and adding a 10% allowance. Water was available all the time. The feed refusals were collected and weighed every morning before offering RGH. Feed samples were collected daily and oven dried. Samples were bulked on weekly basis and sub-samples take for chemical analysis.

At the start of the digestibility trial, rams were weighed using an electronic weighbridge and drenched with antihelimintic. The 15 Doper rams were allocated to the five treatments with three replicates in a complete randomised design and individually confined in metabolic cages with provisions for basal diet and water on offer all the time. The rams were fed on similar diets as Sahiwal weaners. Total daily faecal and urine outputs for each individual animal were collected after every 24 h in the morning at 8.00 h for 7 days after an adaptation period of 14 days. The weights were recorded and subsequently 10% of faecal weight for every animal was taken into plastic bottles and stored in a deep freezer for later analysis while 100 ml of urine from each animal was put into plastic containers containing 10% sulphuric acid to maintain the pH below 3. Urine samples were stored at -20 ^oC until analysed for N. During the last two days of the digestibility trial, 100 ml of rumen liquor were collected from every ram at 0 (before supplementation), 3, 6, 9 and 12 h after supplementation was given. The collection was done using a stomach tube that was attached to a vacuum pump. The pH of the sample was determined immediately by using a pH meter. The sample was strained using a clean cotton cloth and divided into two equal portions and one portion was acidified with sulphuric acid and stored at -20 ^o C for analysis of NH₃-N and the second portion was acidified with metaphosphoric acid and stored at 4 ^oC for later analysis of VFA.

Samples for chemical analysis were oven dried at 70 ^oC for 48 hours and ground to pass through a 1 mm mill screen. Kjehldah nitrogen (N) and ash was determined by the method of AOAC (1990). Neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) were determined according to the method of Van Soest et al (1991). Calcium was determined by using Atomic Absorption Spectrophotometer and phosphorus by spectrophotometer (AOAC 1990). Analysis for VFA was done using Varian gas liquid chromatograph (GLC-3400) equipment.

To determine the in sacco degradation characteristics of samples, 5 g of dry samples in duplicate after being milled to pass through a 2.5 mm screen were weighed in nylon bags (140 mm x 75 mm, pore size 40-60 microns). The bags were incubated in the rumen of two Friesian cannulated steers that were offered Rhodes grass hay ad libitum. The animals were supplemented with 1 kg of dairy meal each daily plus minerals and had free access to water. Nylon bags were withdrawn at 3,6, 12, 24, 48, 72, and 96 h after incubation. The 0 hour measurement was obtained by soaking the two bags of each sample in warm water (39 ^oC) for 1 hour. The 0 hour and incubated bags were washed with cold running water for 15 minutes using domestic washing machine and oven dried at 60 ^oC for 48 h. The DM degradation data was fitted to the exponential equation

P = a + b (1^e-ct) (Ørskov and McDonald 1979; McDonald 1981)

to determine the degradation characteristics (a, b, A, B, A+B, c, ED); where:

P is the DM degradation at time t,
A denotes washing loss which represents the soluble fraction of the feed,
B = (a + b) - A, is insoluble but fermentable fraction;
c is the rate of degradation of B;
a represents zero intercept;
ED denotes effective degradability, calculated at an out flow rate of 0.05 h^-1.

Metabolizable energy (ME) was calculated using the method of Menke and Steingass (1988): ME (MJ/kg DM) = 14.78-0.014 ADF where ADF = acid detergent fiber.

Statistical analysis

Analysis of variance (ANOVA) was carried out on DMI, digestibility coefficiedns, average daily gain, NH3-N, and VFA using the General Linear Model of SAS computer package (SAS 1987). An F test of 5% probability level was used to test for significance differences between means, which were separated by Duncan's New Multiple Range Test.

Results

The results of the chemical composition of the treatment diets are presented in Table 1. The CSCBR had highest (P<0.05) CP content (156 g/kg DM) while RGH had the lowest  (74.1 g/kg DM). The CSCBR and PMBR had low NDF content (345 and 329 g/kg DM respectively) while RGH had high NDF content (720 g/kg DM). PMBR had high levels of ash, Ca and P while both CSCBR and PMBR had similar amounts of estimated ME.

The control group (T1) had the lowest DMI (2.5 kg/day).  The group supplemented with 1 kg PMBR had the highest DMI (Table 2). The DMD was highest for the group supplemented with 1 kg CSCBR but was similar among the other groups. The ADG varied widely across the treatment diets. The unsupplemented group gained the least while the group supplemented with 1 kg CSCBR gained the most.

The amount of volatile fatty acids (VFAs)  varied across the treatments (Table 3). Treatment PMBR animals had higher levels of acetic and propionic acids while treatment 1.0CSCBR had higher levels of butyric and isobutyric acids. Rumen ammonia levels increased with the increase in supplementation and were higher for the PMBR than the CSCBR diets. However, supplementation did not have a clear effect on the rumen pH.

The nitrogen intake (NI) increased with the increase in the amount of supplementation (Table 4). The animals consuming the CSCBR had higher NI than the PMBR while at similar level of supplementation, the nitrogen balance did not differ (P>0.05) between the animals.

Discussion

The chemical composition of the diets was comparable to that reported in the literature for similar diets. For instance, Irungu et al (1981) reported CP content of pyrethrum marc similar to the one found in this study. The CP content of the basal diet was also similar to that reported by Waweru et al (2004) but higher than that reported by Ondiek et al (1999). The CP content of the supplemented diets was generally high and can be considered adequate for supplying nitrogen to the rumen microbes, assuming that the CP is adequately degraded in the rumen. The diets had adequate levels of calcium and phosphorus and the minerals occurred in the recommended ratio of 1:1 or 2:1 for ruminant animals (McDowell and Conrad 1990). Supplementation of the basal diet tended to increase significantly (P<0.05) the total DMI. However, there were no significant differences in the total DMI between the treatments 0.5CSCBR, 1.0CSCBR and 0.5PMBR, suggesting that at higher levels of supplementation, PMBR can substitute the more expensive CSCBR. In both cases, there was no substitution effect of the basal diet noted. Substitution of part of the basal diet by the supplement depends on the quality of the basal diet (Gulbransen 1974). The quality of the basal diet used in this study was good and hence there was no substitution effect. The general increase in the total DMI due to supplementation could be due to the provision by the supplements of protein and energy for improved rumen microbial activities. The results indicate that such supplements can be used to improve the DMI of poor quality forages for ruminants especially under tropical conditions. The ADG increased significantly with supplementation with both CSCBR and PMBR. The ADG in this study compares well with 250 g/day reported by Gitau et al (1994) for smallholder dairy farms in Kenya. At higher level of supplementation, the ADG obtained with PMBR was similar to that of CSCBR indicating the potential of pyrethrum marc in supplementary feeding of animals.

Optimising rumen fermentation digestion of forages requires adequate ammonia N in the rumen to supply the N required for microbial growth (Leng 1990). Supplementation increased the rumen ammonia N. Satter and Slyter (1974) noted that a minimum level of 50mg/litre of rumen ammonia N is required for optimal microbial growth in the rumen. Hence, the ammonia N in the current study would be considered adequate. However, when a low N basal diet is used, a rumen ammonia N level of 200 mg/litre is required for optimal voluntary intake of the basal diet (Preston and Leng 1987). The VFA play an important role in the rumen as a source of energy for the animal upon absorption. Supplementation significantly (P<0.05) increased the concentration of propionic acid from 59.9 (RGH) to 72.3 mM (1.0CSCBR) except in 0.5CSCBR (57.0 mM). Methane production constitutes an energetic loss of as much as 10% of the gross food energy. Therefore it would be desirable to diminish this loss, which is accompanied with a beneficial increase in propionic or butyric due to the transfer of hydrogen.  All the animals remained in positive N balance and this is in line with the gain in weight by all the groups of animals used in this study.
 

Conclusions

• The cotton seed cake and pyrethrum marc based rations were comparable in respect of animal performance. Since pyrethrum marc is available in plenty in Kenya and is cheap, it should be fully exploited in for inclusion in ruminant rations.

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