Doctoral Degrees (Centre for Sustainable Agriculture, Rural Development and Extension)

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Browsing Doctoral Degrees (Centre for Sustainable Agriculture, Rural Development and Extension) by Author "Groenewald, I. B."

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    Potato hash silage as an alternative feed resource for smallholder livestock production
    (University of the Free State, 2010-09) Nkosi, Bhutikini Douglas; Groenewald, I. B.; Van der Merwe, H. J.; Meeske, R.
    Several experiments were conducted to evaluate the ensiling of potato hash (PH) during the period. In the first experiment, a laboratory study was conducted to determine the nutritive value and ensiling potential of PH with poultry litter (PL) and ground hay as absorbents, and whey and molasses as additives. Triplicate samples of PH, PL and hay were collected and sampled for nutritive composition. Mixtures of 800 g PH/kg + 200 g/kg (as is basis) of either PL or hay were produced and treated with: no additive, whey and molasses. The experiment was conducted in a 2 x 3 factorial design (2 absorbents x 3 additives). Mixtures were ensiled in 108 anaerobic jars (1.5L) with 18 jars per treatment, and were stored at 24 - 28°C room temperature. Sampling was done on days 0, 4, 10, 20, 40, 60 and 90 for the determination of fermentation quality and nutritive value of the silage. Further, an aerobic stability test was done on day 90 by exposing silage to air for 5 days. The results showed that PH had 845 g/kg moisture, 11.4 metabolizable energy (ME) MJ/kg, 105 g crude protein (CP) /kg dry matter (DM) and 704 g starch/kg DM. Ensiling PH with ground hay compared to PL as an absorbent, resulted in a better quality silage as indicated by improved fermentation characteristics and chemical composition. Whey and molasses addition improved the nutritive value and the fermentation quality of PH silage but the aerobic stability was not improved. In the second experiment, potato hash silage (treated with no additive, whey and molasses) was produced by mixing 800 g PH/kg with 200 g hay/kg (as is basis), and ensiled in 210 L drums for 90 days, and the fermentation quality of the silages was determined thereafter. Diets containing either potato hash silage (PHS) or maize (Zea mays) silage (MS) were formulated and fed ad libitum to 32 South African Dorper lambs (23.5 ± 0.873 kg live weight) for 63 days. A digestibility study was conducted during the last week of the study. Furthermore, digestibility of the 3 PHS were compared using 9 sheep in a 3 x 3 Latin square design. The untreated potato hash silage (UPHS) was poorly fermented as indicated by higher (P<0.05) concentration of butyric acid, ammonia-N and pH compared to the other silages. Higher (P<0.05) dry matter intake (DMI) and daily gains (218 and 250 g/d) were obtained in lambs fed maize silage diet (MSd) and molasses treated potato hash silage diet (MPHSd) compared to the other diets. Nutrient digestibility was lower (P<0.05) in the UPHS diet compared to the other dietary treatments. The fermentation quality of PH was improved with whey and molasses addition. However, the growth performance was improved (P<0.05) with the MSd and MPHSd, suggesting that MPHSd can replace MSd in lamb diet at 20 % dietary inclusion level without any adverse effect on animal performance. In the third experiment, PH was mixed with wheat bran (70:30) as fed basis and ensiled in 210 L drum for 90 days. Three types of PHS : control, bonsilage forte (BF) and Lalsil Fresh LB(LFLB) were produced. After 3 months, the silos were opened and sampled for fermentation characteristics. Diets were produced by mixing PHS with soybean meal (90:10) as fed basis and a digestibility study was conducted using five South African Mutton Merino rams (37.2 ± 2.21 kg liveweight) per diet. Inoculating PHS with BF and LFLB reduced (P<0.05) pH, WSC, butyric acid and ammonia N while increasing the concentration of lactic acid compared to the control. A higher concentration of acetic acid was obtained with LFLB inoculation, which improved the aerobic stability of silage compared to the other silages. Intakes of dry (DM) and organic matter (OM) were not affected. Gross energy (GE) and CP of silage were improved (P<0.05) with BF and LFLB inoculations. Inoculants increased CP, GE and amylase treated neutral detergent fibre (aNDF) digestibility, but did not alter DM or OM digestibility. Inoculating silage with BF improved (P<0.05) digestibility of ether extract compared to the other treatments, and both inoculants improved (P<0.05) N intake and retention compared to the control. It is concluded that BF and LFLB improved silage fermentation and diet digestibility of CP, aNDF and gross energy. Inoculation with LFLB improved aerobic stability whilst BF inoculation reduced it. In the fourth experiment, totally mixed rations (TMRs) that contained 804 g PH/kg were ensiled in 1.5 L jars with or without Lalsil Fresh Lactobacillus buchneri (LB) for 3 months. Jars were opened on days, 0, 3, 7, 10, 21, 45, 60 and 90 of ensiling and sampled for fermentation and chemical composition determinations. Aerobic stability was determined on day 90 of ensiling. Treatments were LB treated TMR (LB-TMR) and untreated TMR (U-TMR). Furthermore, three TMRs that contained 801 g/kg of either maize (280 g DM/kg) or PH (as fed basis) were ensiled for 90 days in 210 L drums for lamb growth and digestibility studies. The ensiled TMRs were: Maize TMR (M-TMR), U-TMR and LB-TMR and were fed to 24 South African Dorper lambs (20± 0.152 kg live weight) that were allocated in 8 lambs per diet. Inoculation with LB decreased (P<0.05) pH, butyric acid, NH3-N, fibre fractions, CO2 production and yeast population while lactic acid, acetic acid and propionic acid concentrations were increased (P<0.05) compared to U-TMR silage. The ensiled LBTMR was aerobically more stable than U-TMR silage as indicated by lower (P<0.05) CO2 production and yeast population and higher concentrations of acetic acid. Higher (P<0.05) feed intake, average daily gain (ADG), nutrient digestibility and N retention occurred in LB-TMR silage compared to the other silages. It was concluded that LB is effective in producing a better quality PHS, as indicated by improved fermentation, aerobic stability, lamb growth performance and digestibility of LB-TMR silage.