Browsing by Author "Cruywagen, C. W."
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- ItemChemical composition, true metabolisable energy content and amino acid availability of grain legumes for poultry(South African Society for Animal Science, 2004) Brand, T. S.; Brandt, D. A.; Cruywagen, C. W.Samples of sweet yellow lupins (Lupinus luteus; n = 4), broad leaf lupins (Lupinus albus; n = 12), narrow leaf lupins (Lupinus angustifolius; n = 8), faba beans (Vicia faba; n = 2), field peas (Pisum sativum; n = 4) and narbon beans (Vicia narbonensis; n = 2) were collected over a two-year period. The physical characteristics (thousand seed and hectolitre mass), chemical composition (dry matter, ash, crude protein (CP), ether extract, acid detergent fibre, neutral detergent fibre and mineral content), energy values (nitrogen corrected true metabolisable energy content (TMEn for roosters)) as well as the lysine and methionine availability (with roosters) of the samples were determined. Lupinus albus had the highest TMEn (12.49 MJ/kg), followed by field peas (11.35 MJ/kg) and narbon beans (11.25 MJ/kg), faba beans (10.90 MJ/kg), L. angustifolius (10.46 MJ/kg) and L. luteus (10.20 MJ/kg). Lupinus luteus had the highest CP concentration (393.6 g/kg) followed by L. albus (381.9 g/kg), L. angustifolius (338.9 g/kg), faba beans (260.0 g/kg), field peas (247.4 g/kg) and narbon beans (237.6 g/kg) (values on a dry matter basis). Lupinus luteus had the highest lysine concentration (22.2 g/kg), followed by L. albus (19.6 g/kg), field peas (19.3 g/kg), L. angustifolius (18.6 g/kg), narbon beans (17.5 g/kg) and faba beans (17.0 g/kg).
- ItemThe effect of age on in sacco estimates of rumen dry matter and crude protein degradability in veal calves(South African Society for Animal Science, 2000) Holtshausen, L.; Cruywagen, C. W.This study was conducted to determine whether rumen dry matter and crude protein degradability in calves aged 8-10 weeks differs from that in mature cows. Five Holstein bull calves were rumen-fistulated at six weeks of age and were used in consecutive weekly 24 h trials from 8-20 weeks of age. Dry matter and crude protein degradability of two starter and two finisher veal calf diets of high or low rumen degradable protein content were estimated from 24 h in sacco incubation. Rumen pH and concentrations of volatile fatty acids and ammonia-nitrogen were determined on a weekly basis. Three rumen-fistulated Holstein cows were also used to evaluate dry matter and crude protein degradabilities of the diets. Estimates of dry matter degradability obtained from calves differed between the low and high degradability diets within weeks. Dry matter degradability differed between the starter and finisher diets (weeks 10 and 11) and remained fairly constant from week 11 to week 20. Crude protein degradability in calves also differed between the low and high degradability diets within weeks. Crude protein degradability increased up to week 12 and then remained constant until week 20. Dry matter and crude protein degradability estimates for the starter diets were both lower than the corresponding values obtained with cows, while estimates for finisher diets were similar. There were no clear trends over time for rumen pH, volatile fatty acid concentrations and ratios, or for rumen ammonia-nitrogen concentrations ion calves. These values showed a degree of variation between weeks and were similar to literature values for mature ruminants.
- ItemEffect of energy sources on ovarian follicular dynamics and oestrous activity of Holstein cows(South African Society for Animal Science, 2018-07-30) Useni, B. A.; Muller, C. J. C.; Cruywagen, C. W.The objective of the study was to evaluate the effects of three nutritional treatments, which differed in energy level and source, on preovulatory follicles, number of follicles and oestrous activity in dairy cows. Twenty two Holstein multiparous cows from the Elsenburg herd were used in this study. After parturition, cows were kept on kikuyu-ryegrass pastures on an ad libitum basis, and allocated to various levels and types of concentrate supplements, which differed in starch and fat contents. The control group received 7 kg/day of a control concentrate, and the treatment groups each received 12.6 kg/day of concentrate. The concentrates contained high starch-low fat (HSLF) and high starch-low fat/low starch-high fat (HSLF-LSHF) levels. The supplement in treatment HSLF was a glucogenic concentrate using maize as the energy source. The supplements in treatment HSLF-LSHF were a combination of a glucogenic concentrate, which was offered for the first 60 days in milk (DIM), similar to treatment HSLF, followed from 61 DIM by a lipogenic concentrate using wheat bran and calcium (Ca) salts of long-chain fatty acids as the energy sources. At 80 ± 10 DIM, cows were synchronized with an Ovsynch protocol without being inseminated before the ultrasonography observation. While they were detained in a shaded neck clamp, cows were assessed individually with an ultrasound scanner every three days for ovarian measurements and follicular activity until the subsequent oestrus. Results showed that ovarian and follicular measurements and the numbers of follicles in various follicle size classes were similar between nutritional treatments. However, the total ovarian follicular counts were significantly higher in cows that received the HSLF and HSLF-LSHF treatments, compared with their counterparts in the control group (i.e. 7.23 ± 0.22, 7.21 ± 0.14 and 6.53 ± 0.19, respectively), through possible improvement in nutritional status. Further research is required to investigate various energy levels and sources that enhance the viability and the quality of the oocyte ovulating from the dominant follicle and improve the intensity and length of the oestrous expression in dairy cows.
- ItemEffect of late prepartum fibre-based diets on the live weight changes and reproduction of Holstein cows in the subsequent lactation period(South African Society for Animal Science, 2019-03-07) Useni, B. A.; Muller, C. J. C.; Cruywagen, C. W.The objective of this study was to evaluate two late prepartum fibre-based diets that differed in nonstructural carbohydrate (NFC) and protein levels on live weight (LW) changes and fertility traits of Holstein cows until 120 days postpartum. At 30 days before calving, 120 pregnant Holsteins (heifers, n = 54 and dry cows, n = 66) from the Elsenburg herd were assigned to two nutritional treatments according to parity, expected calving date, LW, and milk production during the previous lactation. Prepartum heifers and cows were fed independently a similar type and level of a prepartum concentrate, associated with an ad libitum intake of either unchopped oat hay for the control group or a partial total mixed ration (pTMR: oat hay (48%), lucerne hay (43%) and soybean oil cake meal (9%)) for the treatment group. After parturition, cows in both the control and treatment groups were maintained on ad libitum cultivated irrigated kikuyu-ryegrass pastures, supplemented each with a post-partum concentrate of 7 kg/day from calving until 120 days in milk (DIM). As expected, young and still growing primiparous cows were significantly lighter in pre- and post-partum LW traits compared with mature multiparous cows (parity > 3). Prepartum LW of cows was similar between the control and the treatment in both parity groups. Post-partum LW of the primiparous cows differed significantly between the control and the treatment, which were 488 ± 9 and 507 ± 13 kg, respectively. However, no difference was observed in terms of post-partum LW of multiparous cows of the control and the treatment groups, which were 579 ± 10 and 579 ± 8 kg, respectively. Primiparous cows that received the prepartum oat hay-based diet showed significant decrease in post-partum LW loss changes, LWnadir, LW loss at nadir and rate of LW loss from calving to LWnadir in comparison with their counterparts on the prepartum pTMR-based diet, but these LW traits were similar in multiparous cows. Prepartum diets did not have an effect on post-partum fertility parameters of the multiparous cows, whereas primiparous cows that received the control diet recorded a significantly longer interval from calving to first service (CFS) in the subsequent lactation in comparison with their counterparts fed the treatment diet i.e. 117 ± 9 and 86 ± 8 days, respectively. Proportions of cows that were pregnant at 120 DIM were similar in the subsequent lactation between groups that received the prepartum oat hay- and pTMR-based diets in both parity groups. Further research is required to investigate different prepartum feeding periods and nutritional approaches involving various levels and sources of energy and protein nutrients to encourage post-partum metabolic and hormonal responses that benefit the fertility of dairy cows in the subsequent lactation.
- ItemThe effect of rumen inert fat supplementation and protein degradability in starter and finishing diets on veal calf performance(South African Society for Animal Science, 2003) Cruywagen, C. W.; Lategan, E. L.; Hoffman, L. C.Thirty six Holstein bull calves were divided into six groups to determine the effect of protein degradability and rumen inert fat supplementation in starter and finishing diets on nutrient digestibility and veal production. Calves received low (LD) or high (HD) degradable protein diets, with or without rumen inert fat supplementation. Two commercial fat sources were used, Morlac (mlc) and Golden Flake (gf), included in the experimental diets at 2.5% of dry matter (DM). A commercial milk replacer was fed to all calves at 4 L/day for 42 days, followed by 2 L/day until weaning at 49 days of age. Starter diets were offered ad lib. from day 14 to 10 weeks of age and finishing diets ad lib. from 11 to 20 weeks of age. All calves were slaughtered at 20 weeks to determine carcass weight and dressing percentage. There were no significant differences in body weight gain or dry matter intake over the entire 20 week period. Feed conversion ratio (FCR) was improved when fat was supplemented to LD, but not to HD diets. The FCR (DM intake/kg gain) of LD, HD, LDmlc, HDmlc, LDgf and HDgf diets was 3.45, 3.44, 3.07, 3.81, 3.02 and 3.43, respectively. All 36 calves were used in a digestibility trial during week 18 of the study, using chromium oxide as a marker. Apparent digestibility values (%) for LD, HD, LDmlc, HDmlc, LDgf and HDgf, respectively, were 61.7, 65.9, 75.4, 69.0, 75.5 and 67.2 for DM, 61.4, 61.6, 71.3, 68.2, 75.4 and 66.1 for crude protein and 58.6, 66.5, 76.0, 70.9, 78.4 and 70.8 for fat. Dry matter and fat digestibilities were significantly higher when fat was added to LD diets, but not to HD diets. The CP digestibility was significantly higher when fat was added to either the LD or the HD diets. It was concluded that rumen inert fat supplementation to calf diets appears to improve feed conversion ratio and DM and fat digestibilities, but only when added to low degradable protein diets and only after 10 weeks of age. Crude protein digestibility appears to improve with fat supplementation to either high or low degradable protein diets.
- ItemThe effect of the addition of a lactic acid bacterial inoculant to maize at ensiling on silage composition, silage intake, milk production and milk composition(South African Society for Animal Science, 2002) Meeske, R.; Van der Merwe, G. D.; Greyling, J. F.; Cruywagen, C. W.The aim of the study was to determine the effect of the addition of a lactic acid bacterial inoculant to maize at ensiling on the fermentation dynamics during ensiling, aerobic stability of the silage as well as the intake, milk production and milk composition of Jersey cows fed maize silage diets. The inoculant contained Lactobacillus plantarum and Pediococcus acidilactici as well as amylase. Maize was ensiled in laboratory and bunker silos. The inoculant did not result in a more rapid lowering of the pH or a more rapid lactic acid production compared to untreated maize silage made in laboratory silos. Both the control and inoculated maize silages were well preserved with a pH of 3.57 and 3.62, a lactic acid concentration of 66 and 63 g/kg DM and an ammonia nitrogen concentration of 5.88 and 5.10 g/100 g of total nitrogen respectively. No butyric acid was found in either untreated or inoculated maize silage. The maize silages made in the bunker silos were well preserved with a DM of 283 and 307 g/kg silage, pH of 3.50 and 3.51, lactic acid of 37.0 and 35.3 g/kg DM for the control and inoculated maize silage, respectively. The addition of the inoculant to maize at ensiling improved the palatability, intake and the aerobic stability of maize silage compared to the untreated control maize silage. The intake of untreated and inoculated maize silage by Jersey cows was 7.6 and 8.4 kg DM/day for the control and inoculant treatment, respectively. Milk production, milk composition, live weight and condition score of Jersey cows was not significantly affected by the addition of the inoculant to maize silage.
- ItemEffects of energy levels and sources on plasma metabolites and live weight of Holstein cows(South African Society for Animal Science, 2018-07-30) Useni, B. A.; Muller, C. J. C.; Cruywagen, C. W.The objective of the study was to evaluate the effects of nutritional treatments, which differed after calving, on energy levels and sources on plasma metabolite profiles and live weight (LW) changes as an indication of the nutritional status in Holstein cows. During the dry period, pregnant heifers (n = 69) and dry cows (n = 153) from Elsenburg Research Farm were maintained under similar feeding and management conditions. After parturition, cows had ad libitum access to cultivated irrigated kikuyu-ryegrass pastures, and were assigned to three concentrate groups, according to calving date, parity, LW and the milk yield of their previous lactation. The groups were supplemented with various levels and types of concentrate, of which the energy was provided by starch and fat. The control group was offered 7 kg/cow/day of a control concentrate supplement for both primiparous and multiparous groups, while concentrates in treatment groups were fed at 11.6 and 12.6 kg/cow/day for primiparous and multiparous groups, respectively. The control supplement was a maize-based concentrate, which contained low levels of starch. The concentrate components of the treatments consisted of high starch-low fat (HSLF) and a high starch-low fat/low starch-high fat (HSLF-LSHF) combination. The HSLF supplement was a glucogenic concentrate, which contained maize as the energy source. The HSLF-LSHF supplements consisted of a glucogenic concentrate, which was offered for the first 60 days in milk (DIM) as per the HSLF treatment, and was followed from 61 DIM with a lipogenic concentrate containing wheat bran and calcium (Ca) salts of long-chain fatty acids as the energy sources. The results showed that all cows mobilized their body fat reserves, as was evident in changes in plasma non-esterified fatty acids (NEFA) before and after calving. Postpartum plasma NEFA and β-hydroxybutyrate (BHB) did not differ significantly between nutritional treatments in multiparous cows. However, the postpartum levels of plasma NEFA and BHB were significantly higher for the control, indicating a status of advanced negative energy balance (NEB) and possible subclinical ketosis compared with HSLF and HSLF-LSHF treatments in primiparous cows. Postpartum plasma urea levels decreased significantly in both primiparous and multiparous animals in the control group, compared with the HSLF and HSLF-LSHF groups. As affected by time, postpartum LW was significantly lowest and LW loss was significantly highest in cows that received the control supplements compared with HSLF and HSLF-LSHF supplements for primiparous and multiparous cows. In addition, LW lossnadir and the number of days to reach it significantly increased in primiparous cows that received the control concentrate, compared with those of the HSLF and HSLF- LSHF treatments. However, this trend was not observed for multiparous cows. The findings of this study showed that HSLF and HSLF-LSHF treatments improved the nutritional status, as was evident in the reduced extent of NEB and limited LW loss of dairy cows, compared with those in the control group.
- ItemIn vitro degradation of melamine by ruminal microorganisms(South African Society for Animal Science, 2015) Cruywagen, C. W.; Calitz, T.An in vitro study was conducted to determine the extent of melamine degradation in rumen liquor. Rumen liquor was collected from two ruminally cannulated Holstein cows on four separate dates, one week apart. Erlenmeyer flasks (250 mL) were prepared for incubation by adding 1000 mg of a dairy feed substrate, 100 mg melamine and 100 mL incubation medium, purged with CO2 and fitted with rubber stoppers equipped with one-way gas release valves. The initial melamine concentration was thus 1000 mg/L. The substrates consisted of 600 mg of a commercial dairy concentrate, 200 mg lucerne hay and 200 mg oat hay. The incubation medium consisted of 19 mL rumen liquor, 77 mL of Van Soest buffer and 4 mL of a reducing solution. The flasks were incubated at 39 ºC for 0, 6, 24 or 48 hours (two flasks per time in each of four replicates). The 0 h incubation served as a control treatment to enable the calculation of melamine recovery values. For the control treatment (0 h), fermentation was terminated at the onset of the trial by aerating the rumen liquor and submerging the flasks in 50 mm ice. On termination of the incubation, 100 mL 0.2 M perchloric acid was added to each flask in order to dissolve any undegraded melamine. Melamine concentrations were determined by liquid chromatography-tandem mass spectrometry. Melamine degradation was low after 6 hours and 24 hours of incubation (3.2% and 5.5%, respectively) and increased to 13.6% after 48 h of incubation. It was concluded that melamine has low degradability in rumen liquor.
- ItemMilk production and in sacco disappearance of pasture NDF in grazing Jersey cows receiving a barley based concentrate(South African Society for Animal Science, 2007) Lehmann, M.; Meeske, R.; Cruywagen, C. W.The aim of the experiment was to determine the effect of feeding low (2.4 kg/d), medium (4.8 kg/d) and high (7.2 kg/d) levels of a barley-based concentrate on milk production and in sacco ruminal disappearance of dry matter (DM) and neutral detergent fibre (NDF) in Jersey cows grazing a Westerwold ryegrass pasture. Sixty Jersey cows in early- to mid lactation were randomly allocated to one of three treatments (n = 20). Milk production tended to increase when concentrate level was increased from 2.4 to 4.8 kg/day. Fat corrected milk yield, milk fat yield and milk fat percentage were not affected by treatment. Protein yield only increased when the concentrate level was increased from 2.4 to 4.8 kg/cow per day but there was no further increase when feeding the high level of concentrate. Live weight change and body condition score only increased when the concentrate was fed at 7.2 kg/cow per day. An additional 12 Jersey cows, fitted with ruminal cannulae, were randomly allocated to the High and Low concentrate treatments in a two-period crossover design. Rumen liquid samples were collected every four hours for the determination of rumen pH and volatile fatty acid (VFA) concentrations. Rumen pH was not affected by treatment while total VFA, acetate and isovalerate concentrations increased when the level of concentrate mixture was increased. Rumen NH3-N concentrations were not affected by treatment. The in situ nylon bag technique was used to determine DM and NDF degradation of the pasture. Pasture samples were incubated in the rumen for 0, 4, 8, 12, 20, 30, 48, 72 and 96 hours. Increasing the concentrate mixture did not affect in situ disappearance of pasture DM and NDF, or the rate of degradation. It was concluded that the supplementation of a barley based concentrate to pasture based Jersey cows does not improve animal response when fed at levels higher than 4.8 kg/cow per day. © South African Society for Animal Science.
- ItemMilk production of dairy cows as affected by the length of the preceding dry period(South African Society for Animal Science, 2014-08-22) Useni, B. A.; Muller, C. J. C.; Cruywagen, C. W.The objective of the study was to determine the effect of the duration of the dry period (DP) on the milk yield and milk composition during the following lactation. Milk performance records of 561 Holstein cows, with a previous DP from the Elsenburg Research Farm obtained from the National Milk Recording Scheme, were used in the study. Four groups of dairy cows were identified, based on the duration of their dry period, i.e. cows with a DP of less than 60 days, DP of 61 to 90 days, DP of 91 to 120 days and DP of more than 121 days. The number of records for each group was 76, 162, 83 and 240 lactations, respectively. An ANOVA was conducted using the Generalized Linear Model of SAS to compare milk yield and milk composition according to the DP length. Almost 43% of cows had a DP longer than 121 days, while less than 14% of cows had a DP of less than 60 days. The milk yield was positively affected by DP length. Cows with a DP of less than 60 days produced less milk than cows with longer (more than 61 days) dry periods, e.g. 6462 ± 321 vs. 7393 ± 99 kg. Results were similar for cows in their second and fourth parity. In addition, the milk composition of cows was also affected by DP length, i.e. higher fat and protein levels in the milk from cows with a short DP. Cows in the third lactation with a DP above 121 days produced more milk than the other DP groups. However, the milk composition of cows in the third lactation was not affected by DP length. A DP of less than 60 days reduced milk yield, while an extended DP of more than 121 days would be costly for the dairy farmer even though milk yield was higher. A long dry period may also result due to an excess body condition and calving complications during the subsequent lactation.
- ItemPre- and postpartum effects of starch and fat in dairy cows : a review(South African Society for Animal Science, 2018-01-30) Useni, B. A.; Muller, C. J. C.; Cruywagen, C. W.This review discusses the effects of starch and fat before and after calving on metabolism, energy balance (EB), milk production, and reproduction in dairy cows. The shift in dairy cows from a pregnant non-lactating state to a non-pregnant lactating state induces physiological changes, which affect the metabolic and endocrinal axes to redirect body energy stores towards the mammary gland for milk production. Overfeeding high starch and fat levels during the dry period after calving may result in cows failing to adapt to the negative energy balance (NEB) because of major liver and rumen dysfunction. Alternatively, keeping dry cows on high-forage/low-energy diets adjusts dry matter intake (DMI) to optimize the rumen function and decrease the severity of the NEB during transition. These periparturient biological improvements in dairy cows showed real benefits such as fewer postpartum health complications (e.g. milk fever, ketosis, mastitis, metritis), decreased body condition loss and improved reproductive axis in the subsequent lactation. Adding dietary starch and/or fat to diets of dairy cows following parturition increased milk yield. In addition, milk protein of dairy cows increased with glucogenic diets, but decreased with lipogenic diets. Inversely, milk fat usually increases after feeding lipogenic diets, but it decreases when feeding glucogenic diets to dairy cows. Glucogenic and lipogenic nutrients can affect the cow’s metabolism and its EB status positively, as is evidenced by plasma non-esterified fatty acids (NEFA), β-hydroxybutyrate (BHB), glucose, amino acids, insulin, insulin-like growth factor-I (IGF-I), growth hormone (GH), gonadotropin hormones, and progesterone (P4) levels. These metabolites (NEFA, BHB, glucose, amino acids) and hormones (insulin, IGF-I, GH, P4) have been shown to affect folliculogenesis, ovulation, conception, and pregnancy success. Feeding a starch-based diet to dairy cows can lead to acidosis and increase glucose and insulin levels, while decreasing NEFA and BHB levels. Furthermore, an insulinogenic diet favours an early resumption of ovarian activity, but has adverse effects on the quality of oocytes. In contrast, keeping dairy cows on a fat-based diet elevates NEFA and BHB levels and decreases glucose and insulin levels. Additionally, a lipogenic diet increases the plasma P4 levels and improves the quality of oocytes. These evidences suggest that reproductive performances in dairy cows can be enhanced by feeding an insulinogenic diet until the resumption of the ovarian cycle then switching to a lipogenic diet from mating period onwards. Since long-term field studies on fertility are limited and the reproduction process in dairy cows is multi-factorial, further research is needed on the pre- and postpartum effects of starch and/or fat as well as their combinations on reproduction axis and thus to draw conclusions on reproductive performances.
- ItemReplacing maize grain with dried citrus pulp in a concentrate feed for Jersey cows grazing ryegrass pasture(South African Society for Animal Science, 2017-07-06) Steyn, L.; Meeske, R.; Cruywagen, C. W.Dried citrus pulp (DCP) is a high-fibre by-product of the citrus industry. In total mixed ration (TMR) systems it has been shown to maintain a more stable ruminal environment, improving overall production compared with maize. The aim of the study was to determine the effects of stepwise replacement of maize with DCP in a concentrate supplement on milk yield, milk composition and rumen health of Jersey cows grazing ryegrass pasture. Sixty-eight lactating Jersey cows (μ ± SD; 84.5 ± 43.8 days in milk, 20.4 ± 3.09 kg/day) were used in the trial. Cows were allocated to one of four treatments, with 17 cows per treatment, namely no DCP (NDCP): 0% replacement; low DCP (LDCP): 33% replacement; medium DCP (MDCP): 66% replacement; and high DCP (HDCP): 100% replacement. An additional six ruminally cannulated Jersey cows were randomly allocated to the NDCP and HDCP treatments in a two-period cross-over design. Milk yield decreased between 2.1 and 3.2 kg/day when maize was replaced with DCP. Milk fat content did not differ between treatments. However, treatment had a quadratic effect on milk protein and lactose content, with the LDCP and MDCP treatments having the highest values. No change in the diurnal ruminal pH curve and no differences in the rate and extent of pasture dry matter and neutral detergent fibre degradability between treatments were observed. In conclusion, replacing maize grain with DCP in a conventional concentrate diet led to a decrease in milk yield, while rumen health was maintained.
- ItemRuminal protein and fibre degradability of lucerne hay as affected by regrowth period and dairy breed(South African Society for Animal Science, 2011) Cruywagen, C. W.; Muller, C. J. C.; Du Toit, F. J.The chemical composition of roughages constantly changes while it grows towards maturity. The effective dry matter (DM), crude protein (CP) and neutral detergent fibre (NDF) degradabilities of lucerne hay (LH), harvested after regrowth periods of 4, 5 or 6 weeks, were determined in ruminally cannulated Holstein and Jersey cows by using the in sacco nylon bag technique. The degradabilities of DM and NDF across breeds differed between the LH harvested after the regrowth periods of 4, 5 and 6 weeks. Increasing the regrowth period of LH from 4 to 6 weeks significantly reduced effective DM degradability (k p = 0.08) from 59.0% to 51.2% and NDF degradability from 30.8% to 21.2%. Crude protein degradability tended to decrease with advancing maturity, with values of 77%, 73% and 74% after 4, 5 and 6 weeks' regrowth, respectively. Effective degradability of DM, CP and NDF did not differ between Holstein and Jersey cows. The results from this study suggest that LH harvested after a shorter regrowth period is of a higher quality in terms of DM, CP and NDF degradability which decreases as the plants mature.
- ItemThe use of crude protein content to predict concentrations of lysine and methionine in grain harvested from selected cultivars of wheat, barley and triticale grown in the Western Cape region of South Africa(South African Society for Animal Science, 2000) Brandt, D. A.; Brand, T. S.; Cruywagen, C. W.Correlations were determined between the crude protein (CP) and lysine or methionine concentrations of grain from wheat (cultivar: palmiet), barley (cultivar: clipper) and triticale (cultivar: usgen 19) grown in the Western Cape region of South Africa. Twenty samples of varying CP content were collected for each grain type from different areas within the winter-rainfall sub-region. The relationships between CP content (x; percentage on an air-dry basis) and lysine concentration (y; percentage of CP) were as follows: (wheat) y = 6.380 - 0.198 x, (r2 = 0.85); (barley) y = 6.003 - 0.167 x, (r2 = 0.92); (triticale) y = 5.538 - 0.156 x, (r2 = 0.75). The relationships between CP content (x; percentage on an air-dry basis) and methionine concentration (y; percentage of CP) were as follows: (wheat) y = 2.115 - 0.025x, (r2 = 0.39); (barley) y = 1.527 - 0.030x, (r2 = 0.59); (triticale) y = 1.581 - 0.022x, (r2 = 0.31). It was concluded mat the regression equations may be used as a rapid screening method for predicting the lysine and methionine content of South African wheat, barley and triticale grain from CP content.