This on-farm study was conducted in Zamfara reserve of north western Nigeria between July, 2002 and June, 2003 to assess feed intake and liveweight of 12 indigenous Red Sokoto castrated bucks, separated into two group...This on-farm study was conducted in Zamfara reserve of north western Nigeria between July, 2002 and June, 2003 to assess feed intake and liveweight of 12 indigenous Red Sokoto castrated bucks, separated into two groups of six, supplemented and nonsupplemented respectively. The nonsupplemented group grazed natural pasture and crop stubble of crop fields, whereas the supplemented group grazed natural pasture, crop stubbles and received concentrate supplementation. Concentrate supplement （wheat offal） was fed at 1% of the metabolic weight of the animals which corresponds to the mean of the farmers offer. The total faecal collection method and grab samples of feed were used to estimate total intake of dry matter （DM）, organic matter （OM）, crude protein （CP） and metabolizable energy （ME）. Liveweight of the animal was recorded at five weekly intervals. Results of the study indicated that nutrients intake of supplemented animals were generally higher than those of the nonsupplemented group, but not significantly different （P 〉 0.05）. However, it was observed that supplementation significantly （P 〈 0.05） affected the liveweight of the supplemented bucks during early dry season in December, During this period feed became more available to the grazing animals from crop residues. It was therefore concluded that supplementation with wheat offal at 1% metabolic weight may not be enough to counteract weight loss of grazing goats during the other periods of dry season in this environment.展开更多
An eight-compartment model of the energy dynamics of an alpine meadow-sheep grazing ecosystem was proposed based on SHIYOMI's system approach. The compartments were the above-ground plant portion, the underground...An eight-compartment model of the energy dynamics of an alpine meadow-sheep grazing ecosystem was proposed based on SHIYOMI's system approach. The compartments were the above-ground plant portion, the underground live portion including roots, the underground dead portion including roots, the above-ground litter Ⅰ (degradable portion), the above-ground litter Ⅱ (undegradable portion), the sheep intake, the sheep liveweight, and the faeces. Energy flows between the eight compartments were described by eight simultaneous differential equations. All parameters in the model were determined from paddock experiments. The model was designed to provide a practical method for estimating the effects of the number of rotational grazing subplots, grazing period, and grazing pressure on the performance of grazing systems for perennial alpine meadow pasture. The model provides at least 28 different attributes for characterizing the performance of the grazing system. Analyses of 270 simulated rotational grazing systems of summer-autumn meadow pasture (grazing from 1st June to 30 October each year) provided an inference base to support two recommendations concerning management variables. First, with a three-paddock, 29-day grazing period and 30.14kJ·m -2 ·day -1 grazing pressure scheme, the system has the highest total grazing intake, 4250.44kJ·m -2 , during the grazing season. Secondly, with a three-paddock, 7-day grazing period and 28.89kJ·m -2 ·day -1 grazing pressure scheme, the accumulated graze is 4073.34kJ·m -2 . The potential productivity of the alpine meadow under grazing is defined in this paper as the maximal dry biomass of herbage grazed by the grazing animals over the whole growing season. It has been analysed by applying optimal control theory to the model. The productivity is regarded as the objective function to be maximized through optimization of the time course of the grazing pressure, the control variable. The results show that: (1) under constant grazing pressure, the optimal grazing pressure is f 16 =25.90kJ·m -2 ·day -1 (f 46 =f 56 =0) with the highest accumulated intake of J (1) =3268.17kJ·m -2 ; and (2) the optimal grazing pressure is f 16 =25.94kJ·m -2 ·day -1 (f 46 ≠0, f 56 ≠0) with the maxial accumulated intake J (145) =3500.39kJ·m -2 . Under variable grazing pressure, the dynamics of optimal grazing pressure is shown in Fig.6(a) and Eqs. (9)(11), while the potential productivity (the highest accumulated intake) is J (145) =8749.01kJ·m -2 , 2.5 times the constant grazing pressure.[展开更多
文摘This on-farm study was conducted in Zamfara reserve of north western Nigeria between July, 2002 and June, 2003 to assess feed intake and liveweight of 12 indigenous Red Sokoto castrated bucks, separated into two groups of six, supplemented and nonsupplemented respectively. The nonsupplemented group grazed natural pasture and crop stubble of crop fields, whereas the supplemented group grazed natural pasture, crop stubbles and received concentrate supplementation. Concentrate supplement （wheat offal） was fed at 1% of the metabolic weight of the animals which corresponds to the mean of the farmers offer. The total faecal collection method and grab samples of feed were used to estimate total intake of dry matter （DM）, organic matter （OM）, crude protein （CP） and metabolizable energy （ME）. Liveweight of the animal was recorded at five weekly intervals. Results of the study indicated that nutrients intake of supplemented animals were generally higher than those of the nonsupplemented group, but not significantly different （P 〉 0.05）. However, it was observed that supplementation significantly （P 〈 0.05） affected the liveweight of the supplemented bucks during early dry season in December, During this period feed became more available to the grazing animals from crop residues. It was therefore concluded that supplementation with wheat offal at 1% metabolic weight may not be enough to counteract weight loss of grazing goats during the other periods of dry season in this environment.
文摘An eight-compartment model of the energy dynamics of an alpine meadow-sheep grazing ecosystem was proposed based on SHIYOMI's system approach. The compartments were the above-ground plant portion, the underground live portion including roots, the underground dead portion including roots, the above-ground litter Ⅰ (degradable portion), the above-ground litter Ⅱ (undegradable portion), the sheep intake, the sheep liveweight, and the faeces. Energy flows between the eight compartments were described by eight simultaneous differential equations. All parameters in the model were determined from paddock experiments. The model was designed to provide a practical method for estimating the effects of the number of rotational grazing subplots, grazing period, and grazing pressure on the performance of grazing systems for perennial alpine meadow pasture. The model provides at least 28 different attributes for characterizing the performance of the grazing system. Analyses of 270 simulated rotational grazing systems of summer-autumn meadow pasture (grazing from 1st June to 30 October each year) provided an inference base to support two recommendations concerning management variables. First, with a three-paddock, 29-day grazing period and 30.14kJ·m -2 ·day -1 grazing pressure scheme, the system has the highest total grazing intake, 4250.44kJ·m -2 , during the grazing season. Secondly, with a three-paddock, 7-day grazing period and 28.89kJ·m -2 ·day -1 grazing pressure scheme, the accumulated graze is 4073.34kJ·m -2 . The potential productivity of the alpine meadow under grazing is defined in this paper as the maximal dry biomass of herbage grazed by the grazing animals over the whole growing season. It has been analysed by applying optimal control theory to the model. The productivity is regarded as the objective function to be maximized through optimization of the time course of the grazing pressure, the control variable. The results show that: (1) under constant grazing pressure, the optimal grazing pressure is f 16 =25.90kJ·m -2 ·day -1 (f 46 =f 56 =0) with the highest accumulated intake of J (1) =3268.17kJ·m -2 ; and (2) the optimal grazing pressure is f 16 =25.94kJ·m -2 ·day -1 (f 46 ≠0, f 56 ≠0) with the maxial accumulated intake J (145) =3500.39kJ·m -2 . Under variable grazing pressure, the dynamics of optimal grazing pressure is shown in Fig.6(a) and Eqs. (9)(11), while the potential productivity (the highest accumulated intake) is J (145) =8749.01kJ·m -2 , 2.5 times the constant grazing pressure.[
