The effect of plant age on the chemical composition of fresh and ensiled Agave salmiana leaves

In the first study dry matter (DM), organic matter, crude protein (CP), neutral detergent fibre (NDF) and soluble carbohydrate (SC) concentrations were determined in whole leaves and the upper and lower sections of whole leaves of the Agave salmiana (Otto ex. Salm-Dyck) plant. The pH and saponin concentration were measured in aqueous extracts from these leaves. The leaves were collected from plants at the young (ca. 12 years old), bud (ca. 14 years old) and mature (ca. 16 years old) stages of growth. The CP level of young Agave (48 g/kg DM) leaves was higher than in leaves from the bud (38 g/kg DM) and mature (43 g/kg DM) stages, and higher in the upper (51 g/kg DM) than in the lower (35 g/kg DM) leaf sections. The leaves at the bud stage contained lower NDF (189 g/kg DM) but higher SC (358 g/kg DM) levels than those of mature (272 g NDF, 247 g SC/kg DM) and young (273 g NDF, 189 g SC) plants. The saponin content of leaves was higher in the mature (11.1 g/kg DM) than in the bud stage (7.5 g/kg DM). In the second study the chemical composition of whole leaves from young, bud and mature micro-ensilaged (3.5 kg as fed) Agave was determined over a 36 weeks fermentation period. Agave silage had acceptable chemical characteristics. As time of fermentation increased, a linear decrease in DM and saponin concentration, a linear increase in NDF and lactic acid levels and a quadratic increase of pH values and ammonia-N concentrations were recorded. Both fresh and ensilaged leaves of the mature and the bud stages were the most desirable maturity stages of Agave to be utilised as feed for ruminants. Keywords: Agave salmiana, chemical composition, magueySouth African Journal of Animal Science Vol. 38 (1) 2008: pp. 43-5

Influence of supplemental aminooligosaccharides on in vitro disappearance of diets for dairy cattle and its effects on milk yield

Two experiments were conducted to evaluate the influence of supplemental aminooligosaccharides (AOS) on the disappearance and fermentation of diets for lactating cows, and its effects on milk yield andquality. In the first study, diets containing 0 or 0.2% AOS (dry matter basis) were incubated for 24, 48 and 72 h with ruminal fluid to evaluate the in vitro dry matter disappearance (IVDMD) and fermentationcharacteristics. The addition of AOS improved IVDMD of diets, induced higher total bacterial and cellulolytic bacterial counts and decreased the number of bacteria that produce lactate compared to the control. At 24 h incubation, AOS increased volatile fatty acid concentrations and the molar proportion of propionate, though at 48 and 72 h incubation AOS did not affect the fermentation characteristics of the diets. In a further experiment, milk yield and milk quality were evaluated using 50 Holstein dairy cows (193 days in milk). Cows were randomly assigned to the diets tested in the in vitro study. Feed intake was not modified by AOS. Milk yield of cows fed AOS was significantly higher than that of cows not supplemented. Because AOS tended to decrease the percentage of fat in milk, fat and solid-corrected milk content were similar for the two treatments. Percentage and yield of non-fat solids, protein and lactose, and the somatic cell count in milk were not affected by AOS. The milk urea-N concentration of the cows fed AOS was lower than of thosenot supplemented. Supplementing AOS enhanced the disappearance and fermentation characteristics of the diet. Further studies with cows earlier in lactation are necessary to evaluate the effects of AOS on milk yieldand milk components

Trends in greenhouse gas emissions from dairy cattle in Mexico between 1970 and 2010

The objective of the present work was to estimate and assess trends in greenhouse gas (GHG) emissions, particularly methane (CH4) and nitrous oxide (N2O), from dairy cows in Mexico from the base year of 1970 to 2010. Empirical and mechanistic models were used to estimate enteric methane emissions based on chemical composition of diets. Methane from manure was calculated using Intergovernmental Panel for Climate Change (IPCC) and US Environmental Protection Agency recommended equations. N2O emission was calculated according to IPCC recommendations. Compared with the 1970s, current management practices using modern dairy cows increased feed conversion efficiency 32% and milk yield 62%. GHG emission intensity (i.e. emissions per unit of product) was reduced 30%, 25% and 30% for CH4, N2O and total emissions, respectively. The study showed that although GHG emissions in absolute terms increased in the past 40 years, emission intensity decreased due to higher level of production. This trend is likely to continue in the future, assuming milk production follows the same increasing trend as in other countries in North America. © 2014 CSIRO

Chemical composition and in vitro degradation of red and white mesquite (Prosopis laevigata) pods

The objective of this study was to compare the chemical composition and ruminal degradation of whole pod, exomesocarp, endocarp and seed fractions of red and white mesquite pods. The pods contained on average 220 g free sugars, 78 g crude protein, 21 g fat per kg dry matter (DM), and a potential DM degradation of 163 g/kg. Contaminant fungi (mostly Aspegillus spp.) count was low. Unsaturated fatty acids, mainly linoleic acid, were the predominant (~50%) fatty acids in whole pods and seeds. Sucrose was the largest free sugar proportion. The highest fibre content was found in the endocarp, the highest free sugar was found in the exomesocarp, and the highest crude protein content was found in the seeds. Tannins were more abundant in red pods (0.4 mg/100 g DM) than in white ones. Some differences in nutritional values were found between red and white pods and their components (exomesocarp, endocarp and seeds), although both have a potentially high nutritive value. Whole pods and the endocarp can be used by ruminants; seeds can be used by simple stomach animals; and the exomesocarp can be used in human nutrition because of its low glycaemic index propertiesKeywords: Degradation rate, fatty acids, sugar, tannin

Effects of feeding the seeds of Prosopis laevigata, Acacia schaffneri and Ceratonia siliqua on the performance of broiler chicks

The aim of the present study was to assess the nutrient contents and potential feeding value in the diet of broiler chicks of the seed of three tree species, mesquite (Prosopis laevigata), Schaffneri´s wattle (Acacia schaffneri) and the carob tree (Ceratonia siliqua). The dry matter (DM), ash, crude protein (CP), amino acid and fatty acid concentrations of the seeds were determined. Growth performance was measured in terms of weight gain, feed intake and feed conversion ratio. Sixty-four day-old Cobb broiler chicks were randomly assigned to the following treatments: control diet; control + P. laevigata; control + A. schaffneri and control + C. siliqua. The diets were formulated to contain 200 - 210 g CP/kg and 13.39 MJ ME/kg, with approximately 60 g CP/kg diet originating from the respective seeds. Prosopis laevigata contained the highest protein level (394 g/kg DM), followed by A. schaffneri (229 g/kg DM) and C. siliqua (183 g/kg DM). The concentration of linoleic acid in the fat was found to be the highest in all three species, followed by oleic acid. The methionine concentration in the seed of the three species was low compared with that in soybean meal. Weight gain and feed intake of the chicks were significantly higher in the control diet and there were no significant differences between P. laevigata and A. schaffneri. Chicks receiving C. siliqua had the lowest weight gain. Feed conversion ratio was the lowest in the control diet, with no significant differences between the P. laevigata and A. schaffneri treatments, while C. siliqua had the highest feed conversion ratio. It is concluded that the seeds of the two species, P. laevigata and A. schaffneri, could partially replace commercial feed ingredients as protein and energy sources in diets of poultry kept under subsistence farming conditions in rural areas of Mexico.Keywords: Wild seeds, mesquite, Schaffneri´s wattle, carob, small-scale poultry production, backyar

Short communication: Effect of breed on performance and carcass characteristics of Mexican hair sheep

To determine the effect of breed on growth performance and carcass characteristics in Mexican hair sheep, 48 lambs (average 38.9 ± 1.56 kg body weight, BW) were used in a completely randomized experimental design. The breed types assessed were 16 Pelibuey (PB), 16 Pelibuey x Katahdin (PB-KT) crossbred and 16 Pelibuey x Dorper (PB-DP) crossbred lambs. The lambs were fed a maize grain-based diet (88% concentrate and 12% forage) containing 155 g CP and 12.13 MJ ME/kg DM. The growth performance trial lasted 45 days. The average daily gain was significantly higher for the PB breed than for the PB-KT and PB-DP cross-breds. Feed intake in the PB and PB-KT was significantly higher than in the PB-DP. The feed conversion ratio was lower for the PB than for PB-KT and PB-DP lambs. Hot carcass dressing and leg perimeters were significantly lower for the PB than for the PB-DP lambs, and similar to that of the PB-KT lambs. The lowest dorsal fat values were measured in the PB breed, compared with both the PB-KT and PB-DP cross-breds. Mesenteric fat (as % of BW) in the PB was significantly higher than in PB-KT and PB-DP lambs. Empty rumen and small intestine weights (as % of BW) in the PB lambs were significantly higher than in the PB-DP lambs, but their large intestine was significantly smaller than in the other two breeds. It was concluded that the PB lambs have a better growth performance and carcass characteristics than the PB-DM lambs, but similar to that of the PB-KT lambs.Keywords: Dressing percentage, longissimus dorsi, organ weights, lambs, Pelibuey, Katahdin, Dorpe