Seasonal variations in the chemical composition and dry matter degradability of exclosure forages in the semi-arid region of northern Ethiopia

The present study was conduced at two sites (Tembien and Wukro) in the semi-arid region of Tigray in northern Ethiopia to investigate the seasonal dynamics in the chemical composition and dry matter digestibility of grass and browse species of exclosures. The browse species studied in Tembien and Wukro had a mean crude protein (CP) value of 166 and 117 g/kg dry matter (DM), respectively. The mean in vitro dry matter digestibility (IVDMD) coefficient and predicted metabolizable energy (ME) density of the browse species were 0.72 and 9.83 MJ/kg DM, respectively at Tembien, 0.62 and 8.38 MJ/kg DM, respectively, at Wukro. Neutral detergent fibre (NDF) and acid detergent fibre (ADF) values of the browse species varied from 192 to 437 and 127 to 391 g/kg DM, respectively. Acid detergent lignin (ADL) values ranged from 36 to 190 g/kg DM. The mean CP of the grass species in Tembien and Wukro during the long rainy season was 76 and 73 g/kg DM, respectively and values declined below a critical maintenance level during the dry and short rain seasons. Mean IVDMD and ME values for the two sites were 0.41 and 0.47, and 5.38 and 6.11 MJ/kg DM, respectively. The NDF, ADF, and lignin values of the grass species were generally above 700, 400, and 70 g/kg DM, respectively. The CP, IVDMD and ME values of the mixed grass samples differed (P<0.05) among harvesting months and values ranged from 20 to 103 g/kg DM, 0.47 to 0.72 MJ/kg DM, and 6.16 to 9.91 MJ/kg DM, respectively. The browse species could be used as useful dry season protein supplements to the N deficient native grass species. Especial emphasis should be given to propagate Maerua angolensis and Cadaba farinosa at community nursery sites. Harvesting in September, rather than the current extended harvest period that took place in October and November, can considerably improve the feeding value of native grass hay for smallholder ruminant production systems.     

Nutrient digestibility and prediction of metabolizable energy in total mixed rations for ruminants

The aim of the present study was to determine equations that predict ME in total mixed rations (TMR) based on routine methods. The ME content of 30 TMR for dairy cows was determined based on digestible crude nutrients obtained with wether sheep. Concentrations in the TMR (in g/kg DM) varied between 118 and 234 for crude protein, 26 and 48 for crude lipid, 131 and 250 for crude fibre, 281 and 488 for NDF, and 173 and 304 for ADF. Gas production ranged from 40.7 to 54.1 ml/200 mg DM, and enzymatically degraded organic matter from 652 to 800 g/kg DM. Digestibility [%] ranged from 68.6 to 84.0 for organic matter, from 55.6 to 84.3 for crude lipid, from 55.0 to 77.8 for crude fibre, from 57.6 to 77.0 for NDF and from 53.1 to 79.6 for ADF. ME ranged from 9.6 to 11.9 MJ/kg DM, and NEL from 5.7 to 7.4 MJ/kg DM. ME content was highly correlated with the concentration of both crude fibre and enzymatically degradable organic matter as well as with organic matter digestibility. A multiple regression equation based on crude fibre and crude lipid predicted ME with a reasonable goodness of fit (r² = 0.81; s_y.x = 2.4%). The inclusion of other nutrients, of neutral and acid detergent fibre, neither of gas production did improve the goodness of fit. The best prediction was achieved with inclusion of enzymatically degraded organic matter (r² = 0.90; s_y.x = 1.7%).     

Prediction of the metabolisable energy content of forages and mixed diets for horses: validation and comparison of two evaluation systems

The metabolisable energy (ME) content of feeds is a better estimate of their ‘true’ energy value than their digestible energy (DE) content, because ME takes account of the gross energy of methane (GEgas) and the gross energy of urine (GEurine) losses. The accuracy and precision of the Gesellschaft für Ernährungsphysiologie (GfE) and Institut National de la Recherche Agronomique (INRA) systems for predicting the DE and ME contents of diets for horses were compared using the results of a study comprising 15 mixed diets. The INRA system was more accurate than the GfE system for predicting DE, GEurine and ME: the biases between the predicted and the measured values were − 0.26 vs –0.46 MJ/kg DM for DE (P < 0.05), − 0.03 vs 0.13 MJ/kg DM for GEurine (P < 0.05) and − 0.09 vs –0.62 MJ/kg DM for ME (P < 0.05). The biases for GEgas were not significantly different (P > 0.05) between systems. In addition, a study was carried out with 24 forages to compare the ME value of permanent meadow and lucerne hays predicted with the GfE and the INRA systems. The INRA system gave higher prediction values of DE than the GfE system (P < 0.001) and lower estimates of GEgas (0.34 vs 0.63 MJ/kg DM for permanent meadow hays and 0.38 vs 0.63 MJ/kg DM for lucerne hays) (P < 0.001) and GEurine (0.85 vs 0.93 MJ/kg DM for grassland hays and 1.08 vs 1.37 MJ/kg DM for lucerne hays) (P < 0.001). The INRA system thus gave higher estimates of ME (7.57 vs 6.77 MJ/kg DM for permanent meadow hays and 8.80 vs 6.46 MJ/kg DM for lucerne hays, P < 0.001) in agreement with the results obtained with mixed diets. The ME values of permanent meadow hays and legume hays should therefore be predicted separately using specific equations as previously established for the DE value.     

Effects of feeding cows in early lactation with soy hulls as partial forage replacement on heat production,retained energy and performance

This study measured the effects of replacing corn silage and vetch hay by soy hulls in total mixed rations (TMRs) fed to 25 pairs of cows through 90 d in milk, on dry matter (DM) intake, in vivo digestibility, milk yield and composition, onset of normal estrous activity, body condition score (BCS), health and the energy balance of lactating cows. The partitioning of metabolizable energy (ME) intake between heat production (HP) and retained energy (RE) in milk and body change of each cow was measured. The two TMRs differed in the content of forage and forage aNDFom [235 g/kg versus 350 g/kg; and 128 g/kg versus 187 g/kg DM, in the experimental (EXP) and control (CON) diets, respectively]. This was reflected by an increase in voluntary DM intake by 7.2% (P=0.02) in the EXP group as compared with the CON. In vivo DM and aNDFom digestibility were 4.9% (P=0.03) and 22.7% higher (P=0.01), respectively, in the EXP group than in the CON. The higher DM intake and digestibility of the EXP TMR were reflected by a concomitant increase of 7.4% in milk yield and 10.8% in RE (P=0.01) of the EXP cows as compared with the CON. The two dietary groups expressed similar somatic cell counts, and metabolic disorders (i.e., ketosis and/or lameness), as well as pedometer activity (steps/h) suggesting similar udder health, behavior and animal welfare. A trend to an earlier return to normal ovarian activity occurred in the EXP cows as reflected by fewer days to 1st ovulation and advanced outset of estrous cycle. Despite the higher RE of the EXP cows, the HP of both groups was maintained at an upper level of 141–136 MJ/cow/d during the 90 d of the experiment.     

Influence of condensed tannins from Brazilian semi-arid legumes on ruminal degradability,microbial colonization and ruminal enzymatic activity in Saanen goats

The present study aimed at determining the influence of condensed tannins present in the Brazilian legume species Mimosa hostilis, Mimosa caesalpinifolia and Bauhinia cheilantha on ruminal degradability, microbial colonization and enzymatic activity. Polyethylene glycol (PEG) was used to reduce the astringency and concentration of soluble condensed tannins. Four ruminally-cannulated Saanen goats (60 ± 8 kg BW) were fed, in two experimental periods, with a hay diet based on the studied legumes treated or non-treated with PEG. Voluntary intake, microbial colonization, DM, CP, NDF, and ruminal degradability of PEG treated and non-treated forage leaves, as well as pH, ammonia and 1,4 β-endoglucanase activity of the rumen content were evaluated. Astringency and soluble tannin concentration of the studied legumes were reduced by approximately 70% and 50%, respectively, with PEG treatment. Average DM intake was higher for the treated diet (16.76 g DM/kg BW/day against 13.06 g DM/kg BW/day). Percentile values for degradation parameters and for potential and effective degradabilities of DM, CP and NDF were also affected by the tannins, but at different intensities. Electron microscopic observations of ruminally-incubated legume leaves showed a more effective microbial colonization of PEG-treated leaves for all legume species. A decrease in pH and an increase in ammonia concentration and in endoglucanase activity in the ruminal content was also observed for PEG-treated diets at all sampling periods. Condensed tannins of the studied legume species have influenced the adhesion conditions, colonization and enzymatic activity of the microbial ecosystem, and consequently the ruminal degradation of the different dietary fractions. For this reason, the reduction in condensed tannin would be of great importance to improve the nutrition of ruminant feeding of these species.     

Variations in chemical composition and in vitro and in situ ruminal degradation characteristics of dried distillers’ grains with solubles from European ethanol plants

The objective of this study was to characterise variations in the composition and nutritive value of dried distillers’ grains with solubles (DDGS) for ruminants, and to estimate the undegradable crude protein (UDP) in DDGS. Thirteen samples originating from wheat, corn, barley and blends of different substrates were studied. The rumen degradation of crude protein (CP) was determined using the nylon bag technique. Samples were incubated for 0, 1, 2, 4, 8, 16, 32 and 72 h, and in situ degradation kinetics were determined. The UDP was estimated using a passage rate of 8%/h. In vitro gas production was measured to estimate the metabolisable energy (ME), net energy for lactation (NE_L) and in vitro digestibility of organic matter (IVDOM). Chemical profiles varied among samples [in g/kg dry matter (DM) ± standard deviation]; the values were 310 ± 33 CP, 86 ± 37 ether extract, 89 ± 18 crude fibre, 408 ± 39 neutral detergent fibre, 151 ± 39 acid detergent fibre and 62 ± 31 acid detergent lignin, as well as in protein fractions according to the Cornell Net Carbohydrate and Protein System [in g/kg CP]; the values were for fractions A, 161 ± 82; B1, 24 ± 11; B2, 404 ± 105; B3, 242 ± 61; and C, 170 ± 87. The ME, NE_L [MJ/kg DM] and IVDOM [%] also varied among samples: 12.1 ± 0.59, 7.3 ± 0.39 and 72.5 ± 4.30, respectively. The in situ rapidly degradable CP fraction (a) varied from 10.2% to 30.6%, and the potentially degradable fraction (b) averaged to 66.8%. The UDP varied from 8.6% to 62.6% of CP. The present study suggests significant variations in composition and nutritive value among different sources of DDGS. The UDP could be predicted on the basis of analysed CP fractions, but the accuracy of UDP prediction improved upon the inclusion of neutral-detergent insoluble nitrogen, explaining 94% of the variation in the UDP values. We conclude that chemical protein fractions may be used to predict the UDP values of DDGS and that the variability in the protein fractions of DDGS should be considered when formulating diets for dairy cows.     

Palatability in sheep and in vitro nutritional value of dried and ensiled sainfoin (Onobrychis viciifolia) birdsfoot trefoil (Lotus corniculatus), and chicory (Cichorium intybus)

Three temperate forages, sainfoin, birdsfoot trefoil, and chicory, characterized by elevated contents of plant secondary compounds, were compared to a ryegrass-clover mixture (control) in dried (Experiment 1) and ensiled form (Experiment 2) in their palatability and nutritional value. Palatability was measured in adult wethers (n = 6) allowed to choose between the familiar control forage and one of the three test plants. Palatability index was calculated from differences in intake of control and test plants measured after given times. Generally at first contact, palatability of the unfamiliar plants was low. Lag time until palatability index approached or exceeded a value of 100 was 2-5 d, but could not be related to the content of condensed tannins. Sainfoin had a high palatability, the highest content of condensed tannins (77.4 +/- 10.23 g/kg DM), a high content of duodenally utilisable crude protein (94.7 +/- 16.87 g/100 g CP), and a high content of metabolizable energy (9.5 +/- 0.38 MJ ME/kg DM), making this plant most promising for various purposes including anthelmintic action.     

Investigations on the effect of the ruminal N-balance on rumen metabolism, urea content in blood serum and milk as well as some liver parameters of lactating cows

Seven dairy cows fitted with ruminal and duodenal cannulae were used to investigate the influence of the amount of ruminally available N (Ruminal N-Balance, RNB) on the rumen metabolism and to answer the question on the lowest N-amount in the rumen, without negative effects on the fermentation. Animals were fed a ration on the basis of 7.9 kg corn silage and 7.2 kg concentrates related to dry matter, intended to meet the animals mean NEL and protein requirements. RNB amounted to -0.6 g/MJ ME in the basis ration. The other 3 rations were adjusted to RNB-values of -0.3, 0 and + 0.3 g/MJ ME by urea supplements in the concentrates. The increase in RNB resulted in higher NH3-N concentrations in the rumen fluid and in the duodenal digesta and higher urea concentrations in the blood and milk. The significantly highest amount of protein at the duodenum was detected when RNB showed an equilibrium (RNB = 0). The efficiency of microbial protein (MP) synthesis (gMP/kg fermented organic matter) was the same, g MP/d and g MP/MJ ME were significantly lower with RNB = -0.6g/MJ ME as compared to RNB = 0. The group with thelowest RNB showed the highest level of feedprotein degradation as well as the lowest organic matter, NDF and ADF fermentation. An effect on cholesterol, total bilirubin and gammaGT due to different RNB was not detected. The activities of GLDH and AST were highest when the RNB was -0.6 g/MJ ME. From the results, it can be concluded that significantly negative effects on rumen fermentation occur when RNB-values are below -0.3 g/MJ ME. However, a positive RNB did not increase t he degradation and synthesis capacity of the rumen micro-organisms as compared to RNB = 0.     

Effects of the dietary protein content and the feeding level on protein and energy metabolism in Iberian pigs growing from 50 to 100 kg body weight

Nutritional requirements of the Iberian pig, a slow-growing, obese porcine breed, are not well defined and seem to differ from those of conventional or high-performing pigs. The effects of the dietary protein content and the feeding level on the utilisation of metabolisable energy (ME) and the rates of gain, protein, and fat deposition were studied with 81 Iberian castrates growing from 50 to 100 kg body weight (BW) by using the comparative slaughter technique. The animals were fed 4 diets providing 145, 120, 95, and 70 g ideal crude protein (CP) per kg dry matter (DM), and containing 13.94, 14.29, 14.56, and 14.83 MJ ME per kg DM, respectively. Three levels of feeding were evaluated: 0.60, 0.80, and 0.95 × ad libitum intake. Growth rate increased (linear and quadratic, P < 0.001) as the dietary ideal CP content decreased. It also increased with the feeding level (linear, P < 0.001; quadratic, P < 0.05). Gain:feed and gain:ME intake improved by decreasing the ideal CP content in the diet (linear, P < 0.001 and P < 0.05, respectively; quadratic P < 0.001 for both variables). Increasing the feeding level improved linearly gain:feed and gain:ME intake ( P < 0.001). Protein deposition (PD):ME intake ranged between 1.23 and 1.44 g/MJ, and it showed a tendency to reach the maximum value when the diet providing 95 g ideal CP per kg DM was fed (quadratic, P = 0.078). When this diet was offered at 0.95 × ad libitum, PD reached a maximum value of 71 g/day. This dietary treatment resulted in average values for average daily gain and retained energy (RE) of 854 g/day and 21.4 MJ/day, respectively. The average rate of gain was 19.93 g/MJ increase in ME intake, equivalent to an energy cost of 50.2 kJ ME per g gain, irrespective of the dietary ideal CP content. Also, the overall marginal efficiency of protein deposition (ΔPD:ΔME; g/MJ) was 1.34. Increasing the feeding level led to increases in PD (linear, P <  0.001) and RE (linear, P <  0.001; quadratic, P <  0.01) irrespective of the dietary ideal CP concentrations. Between 50 and 100 kg BW, the chemical composition of 1 kg gain averaged 78, 592, 28.7, and 284 g for CP, fat, ash, and water respectively. The net efficiency of use of ME for growth ( k_g) and the maintenance energy requirements were 0.606 and 396 kJ/kg BW ^0.75 per day, respectively. The results support earlier findings that the genotype has marked effects on protein and energy metabolism of growing pigs and underline important compositional differences of the Iberian pig compared with conventional or modern porcine genotypes.     

Nutritional and ecological evaluation of dairy farming systems based on concentrate feeding regimes in semi-arid environments of Jordan

The objective of this study was to evaluate the nutritional and ecological aspects of feeding systems practiced under semi-arid environments in Jordan. Nine dairy farms representing the different dairy farming systems were selected for this study. Feed samples (n = 58), fecal samples (n = 108), and milk samples (n = 78) were collected from the farms and analysed for chemical composition. Feed samples were also analysed for metabolisable energy (ME) contents and in vitro organic matter digestibility according to Hohenheim-Feed-Test. Furthermore, fecal nitrogen concentration was determined to estimate in vivo organic matter digestibility. ME and nutrient intakes were calculated based on the farmer’s estimate of dry matter intake and the analysed composition of the feed ingredients. ME and nutrient intakes were compared to recommended standard values for adequate supply of ME, utilizable crude protein, rumen undegradable crude protein (RUCP), phosphorus (P), and calcium (Ca). Technology Impact Policy Impact Calculation model complemented with a partial life cycle assessment model was used to estimate greenhouse gas emissions of milk production at farm gate. The model predicts CH₄, N₂O and CO₂ gases emitted either directly or indirectly. Average daily energy corrected milk yield (ECM) was 19 kg and ranged between 11 and 27 kg. The mean of ME intake of all farms was 184 MJ/d with a range between 115 and 225 MJ/d. Intake of RUCP was lower than the standard requirements in six farms ranging between 19 and 137 g/d, was higher (32 and 93 g/d) in two farms, and matched the requirements in one farm. P intake was higher than the requirements in all farms (mean oversupply = 19 g/d) and ranged between 3 and 30 g/d. Ca intake was significantly below the requirements in small scale farms. Milk nitrogen efficiency N-_eff (milk N/intake N) varied between 19% and 28% and was mainly driven by the level of milk yield. Total CO₂ equivalent (CO₂ equ) emission ranged between 0.90 and 1.88 kg CO₂/kg ECM milk, where the enteric and manure CH₄ contributed to 52% of the total CO₂ equ emissions, followed by the indirect emissions of N₂O and the direct emissions of CO₂ gases which comprises 17% and 15%, respectively, from total CO₂ equ emissions. Emissions per kg of milk were significantly driven by the level of milk production (r² = 0.93) and of eDMI (r² = 0.88), while the total emissions were not influenced by diet composition. A difference of 16 kg ECM/d in milk yield, 9% in N-_eff and of 0.9 kg CO₂ equ/kg in ECM milk observed between low and high yielding animals. To improve the nutritional status of the animals, protein requirements have to be met. Furthermore, low price by-products with a low carbon credit should be included in the diets to replace the high proportion of imported concentrate feeds and consequently improve the economic situation of dairy farms and mitigate CO₂ equ emissions.     

Energy supply of the okapi in captivity: fermentation characteristics of feedstuffs

A variety of feeds are used in the nutrition of browsing ruminants. During digestion trials on okapis, feedstuffs of different facilities were sampled and the Hohenheim gas test was used as in vitro fermentation method to quantify their fermentative behavior. Forty‐six feeds were analyzed (7, fruit and vegetable; 11, energy concentrates and pelleted compounds; 13, forage; 9, browse leaf; 6, small and large twig samples). Gas production of these samples was recorded after 2, 4, 6, 8, 10, 12, and 24 hr of fermentation. Browse leaf samples were additionally analyzed with a tannin‐binding agent (polyethylene‐glycol) to assess limiting effects of condensed tannins. Metabolizable energy (ME) was estimated from 24 hr gas production according to standard regressions. Vegetables and particularly fruits were found to yield very high gas productions during the first 2 hr of fermentation, whereas unmolassed beet pulp was found to have a more even distribution of gas production/energy release over total fermentation time. Feeds like rolled oats or bread were evaluated to yield very high energy contents of >14 MJ ME/kg dry matter (DM). Alfalfa (Medicago sativa) hay had a comparable fermentation pattern to fresh browse samples, characterized by a high fermentation rate. In conclusion, energy‐rich constituents for captive ruminant diets should not include larger amounts of vegetables and especially fruits, due to their very fast fermentation during the initial phase of fermentation and the connected risk of rumen acidosis. Energy‐concentrates like beet pulp (unmolassed) showed moderate fermentation characteristics and energy content and are well suited as a component of zoo ruminant diets. Energy‐concentrates with very high energy densities (>13 MJ ME/kg DM) like bread or rolled oats are not suitable for a diet that is intended to promote long feeding times. Various aspects are involved in the decision for appropriate forage for browsing ruminants; based on fermentation pattern, alfalfa hay seems to be a reasonable substitute for browse leaves. Zoo Biol 0:1–16, 2006. © 2006 Wiley‐Liss, Inc.     

Nutritional characterization of Mucuna pruriens: 1. Effect of maturity on the nutritional quality of botanical fractions and the whole plant

This study was conducted to determine the stage of maturity at which the dry matter (DM) yield and nutritive value of velvet bean (Mucuna pruriens) is optimized. Mucuna was harvested at 77, 110 and 123 days after planting (DAP) from quadruplicate 5 m × 1 m plots within each of 6 blocks. At each DAP, DM yield, chemical composition, botanical composition, in vitro rumen fluid-pepsin DM digestibility (IVDMD) and concentrations of total polyphenols, l-dopa and tannins were determined on the whole plant and botanical fractions. Whole-plant Mucuna DM yield increased (P<0.01) linearly with maturity; proportions of leaves and stems decreased linearly (P<0.01), whereas proportion of pods increased (P<0.01). Concentrations of neutral-detergent fiber (aNDF) in whole plant, leaf, and stem increased (P<0.05), or tended (P<0.10) to increase linearly with maturity, as did the acid-detergent fiber concentration of leaves and stems. Maturity decreased (P<0.05) ether extract concentrations of leaves linearly, and stems quadratically, but increased (P<0.05) whole-plant and pod starch concentrations. Pods contained relatively high concentrations of lysine, histidine, phenylalanine, aspartate, glutamate, leucine, isoleucine, and valine, but low concentrations of methionine and cystine. The essential amino acid index did not vary with maturity. Most minerals in Mucuna are concentrated in the leaves and the whole plant contains sufficient Ca, P, K, Mg, Fe, Cu, Na, Mo, Mn, and Zn for growing sheep, although their bioavailability of these minerals is unknown. Total polyphenol concentration quadratically (P<0.01) increased with maturity in the whole plant, tended to increase (P<0.10) in pods, linearly (P<0.01) decreased in stems and fluctuated in leaves. Maturity quadratically increased l-dopa concentration of the whole plant (P<0.05) and stems (P<0.01), but did not affect those of leaves and pods. Maturity quadratically increased (P<0.05) total tannin concentration in the whole plant, but decreased (P<0.10) that of pods. The l-dopa was concentrated in the seeds and pods of mature (110–123 DAP) plants, but tannins were concentrated in leaves and stems. Whole-plant IVDMD was not affected by maturity, but digestible DM yield linearly (P<0.01) increased with increasing DM yield. There was a 2-week harvest window (110–123 DAP) during which whole-plant crude protein and IVDMD remained unchanged. Nevertheless, harvesting at 123 DAP gave the best combination of biomass yield and nutritive value.     

Effect of feed restriction or feeding high-fibre diet during the rearing period on body composition, serum parameters and productive performance of rabbit does

This study evaluated the effect of different feeding regimes from 11 weeks of age to first parturition on feed intake, leptin, non-esterified fatty acids (NEFA) and total protein serum levels, as well as productive performance in young rabbit does. In addition, body composition was estimated by bioimpedance analysis. Thirty-six 11-week-old does were randomly distributed in three groups. The AL-C group was fed ad libitum a control diet containing 350 g neutral detergent fibre (aNDFom)/kg, 11.6 MJ digestible energy (DE)/kg and 173 g crude protein (CP)/kg, and the does were inseminated at 16 weeks of age. The R-C group was fed 150 g/d of the same diet until 16 weeks of age, one week before artificial insemination (AI) at 17 weeks of age, and then fed ad libitum. The AL-F group was fed a diet containing 475 g aNDFom/kg, 9.4 MJ DE/kg and 174 g CP/kg ad libitum, and was inseminated at 17 weeks of age. During rearing (11-16 weeks), does in the R-C group had the lowest DE (1.54 MJ/d; P<0.003) and digestible protein (DP, 17.9 g/d; P<0.001) intake, as well as the lowest protein (172 g/kg; P<0.05) and energy (5.9 MJ/kg) body contents, leptin concentration at 16 weeks of age (2.48 ng/ml; P<0.001) and fertility (P<0.02) at first AI. Daily feed intake during pregnancy and lactation, as well as prolificacy and litter weight, were similar among groups. The highest percentage of body fat was observed for all the does when were inseminated for the first time (135 g/kg; P<0.001), consistent with the highest leptin (4.48 ng/ml; P<0.001) and total protein serum levels (6.87 g/dl; P<0.001) at this time. Serum NEFA level around parturition was higher (P<0.05) in groups AL-C and R-C (1.11 and 0.85 mmol/l) than in group AL-F (0.71 mmol/l), suggesting a lower lipid mobilization that tended to improve fertility rate for AL-F does on day 11 post-parturition (P<0.09). In conclusion, feed restriction during the rearing period delays reproductive development in young rabbits. In nulliparous does, ad libitum feeding during rearing with a high-fibre diet allows a similar productive performance to that of feeding with a less fibrous diet. Nevertheless, the use of high fibre diets during rearing does not affect feed intake throughout the first pregnancy and lactation.     

A calorimetric investigation of the nutritive value of formic acid- and formaldehyde—Formic acid-treated grass silages

Experiments were conducted to study the utilisation of a ryegrass mixture preserved chemically by formic acid (silage 1) of mean gross energy (GE) 18.6 MJ/kg dry matter (DM), and formaldehyde—formic acid (silage 2) of mean GE 18.3 MJ/kg DM. The parent grass and resulting silages were analysed chemically and calorimetric balance trials were performed with four sheep fed at maintenance and 1.5 times maintenance.Silages 1 and 2 had similar, high digestibility coefficients for DM (0.732 and 0.718), organic matter (OM) (0.755 and 0.742), and energy (E) (0.730 and 0.710). The digestible energy (DE) contents of silages 1 and 2 were 13.3 and 12.7 MJ/kg DM, respectively, at the lower level of feeding and 13.8 and 12.8 MJ/kg DM, respectively, at the higher level. The metabolisable energy (ME) contents of silages 1 and 2 were 11.6 and 10.8 MJ/kg DM, respectively, at the lower level of feeding and 12.0 and 11.0 MJ/kg DM, respectively, at the higher level.The mean efficiency of utilisation of ME for growth (K_g) for silages 1 and 2 was 0.43 and 0.39, respectively; these results are in broad agreement with those predicted by other workers.     

Effect of zinc supplementation from two sources on growth,nutrient utilization and immune response in male crossbred cattle (Bos indicus×Bos taurus) bulls

To investigate effects of Zn supplementation on performance, mineral balance and immune response, 15 male crossbred cattle (Bos indicus×Bos taurus) bulls of about 14 ± 0.4 months of age and weighing 226.0 ± 9.1 kg were divided in to three groups of five. Bulls in the control group were fed wheat straw and a concentrate mixture (basal diet with 32.5 mg Zn/kg dry matter (DM)), and in ZnSO₄ and ZnProp groups 35 mg Zn/kg DM was added through Zn sulphate and Zn propionate, respectively. All bulls were fed their respective treatment diets for 180 days. Daily feed intake was recorded and bulls were weighed at every 15 days to determine change in body weight (BW). After 120 days of feeding, bulls were vaccinated with Brucella abortus strain 19, and cell mediated and humoral immune responses were assessed between 120 and 148 days of experimental feeding. After 150 days of feeding, a metabolism study of 6 days duration was completed to determine nutrient digestibility and mineral balances (i.e., Ca, P, Zn, Cu, Fe and Mn). Intake of total DM, digestibility of DM, crude protein, ether extract, neutral detergent fibre and acid detergent fibre, N balance, average daily gain, feed: gain did not differ between the groups. Intake, excretion and balance of Ca, P, Zn, Cu, Fe and Mn also did not differ between the groups. However, retention of Zn was higher (P<0.001) in the ZnProp group. Bulls supplemented with Zn propionate had higher cell mediated (P<0.01) and humoral (P<0.05) immune response, while there was no alteration in immune response due to Zn sulphate supplementation. Results indicate that a diet containing about 32.5 mg Zn/kg DM was adequate to support normal growth and digestibility, but a better immune response occurred when Zn propionate was added to the diet at 35 mg/kg DM versus Zn sulphate.     

Effect of willow supplementation upon plasma amino acid concentration in ewes grazing drought pastures of low nutritive value

Effects of supplementing willow stem cuttings to ewes grazing drought pastures upon plasma amino acid (AA) concentrations was studied on Massey University's Riverside Farm, near Masteron, on the East Coast of New Zealand. Ewes of similar age and weight (i.e., 59.0 ± 2.22 kg) were assigned to two groups of 7 each, either with (supplemented) or without (control) supplementation of willow, and experimental grazing was carried for 10 weeks from early February until mid April of 2005. Live weight (LW) was recorded fortnightly and body condition score (BCS) was monthly. Blood samples for quantification of plasma amino acids were collected at week 5 and 10. Both groups had a similar pre-grazing pasture mass (i.e., 2000 kg of dry matter/ha) and dead matter content (0.80) with the diet selected by the ewes containing a metabolisable energy (ME) of 8.3 MJ/kg DM, which is typical of drought conditions. The willow was readily eaten, with intake averaging 0.26 kg DM/ewe/d. Willow was of higher ME content than short drought pasture (i.e., 10.1 versus 8.4 MJ/kg DM) and contained condensed tannins at 40.8 ± 1.97 g/kg DM. Both groups of ewes lost live weight at about 50 g/d. Plasma concentration of 3-methyl histidine (88 versus 127 μmol/L) at week 5 and non-essential amino acids (1082 versus 1417 μmol/L) at week 5 and (1155 versus 1324 μmol/L) at week 10, were substantially lower (P<0.05) in willow supplemented versus control ewes, indicating that willow supplementation reduced catabolism of body proteins in ewes under drought feeding conditions.     

Palatability in sheep and in vitro nutritional value of dried and ensiled sainfoin (Onobrychis viciifolia) birdsfoot trefoil (Lotus corniculatus), and chicory (Cichorium intybus)

Abstract

Three temperate forages, sainfoin, birdsfoot trefoil, and chicory, characterized by elevated contents of plant secondary compounds, were compared to a ryegrass-clover mixture (control) in dried (Experiment 1) and ensiled form (Experiment 2) in their palatability and nutritional value. Palatability was measured in adult wethers (n = 6) allowed to choose between the familiar control forage and one of the three test plants. Palatability index was calculated from differences in intake of control and test plants measured after given times. Generally at first contact, palatability of the unfamiliar plants was low. Lag time until palatability index approached or exceeded a value of 100 was 2 – 5 d, but could not be related to the content of condensed tannins. Sainfoin had a high palatability, the highest content of condensed tannins (77.4 ± 10.23 g/kg DM), a high content of duodenally utilisable crude protein (94.7 ± 16.87 g/100 g CP), and a high content of metabolizable energy (9.5 ± 0.38 MJ ME/kg DM), making this plant most promising for various purposes including anthelmintic action.     

Nutritive value of peas for nonruminant diets

Peas, the seeds of Pisum sativum, are produced usually in temperate regions but are accepted as a food source worldwide. Traditionally, nonruminant diets utilized peas which had been rejected by the food industry but specific cultivars of feed (or field) peas also have been developed for livestock use. In view of the diversity of varieties, seeding times (spring or winter-sown) and agronomic conditions during the growing season, there is a considerable range in the composition and nutritive value of peas. The seed coat (hull) represents 70 to 140 g kg⁻¹ of the total weight and consists mainly of non-starch polysaccharides, while the major components of the dehulled pea are starch ( 450 g kg⁻¹) and protein ( 250 g kg⁻¹). Published energy values for the whole seed range from 12.2 to 16.6 MJ ME kg⁻¹ DM for pigs and 10.1 to 12.8 MJ TME_N kg⁻¹ DM for poultry. Reported analyses for crude protein vary from 156 to 325 g kg⁻¹ DM, while content and availability of the constituent amino acids vary also with cultivar, seed type and analytical methods. Most concerns about low digestibilities relate to the sulphur amino acids and tryptophan. Potentially detrimental constituents in raw peas include anti-proteases, haemagglutinins, phytic acid and tannins although these appear negligible in Canadian peas. When analytical data are lacking, the following limits to use of peas are suggested: 100, 200 and 350 g kg⁻¹, respectively, in pig starter, grower and finisher diets; 200 g kg⁻¹ in broiler, 250 g kg⁻¹ in turkey and 300 g kg⁻¹ in layer diets.     

Effect of niacin supplementation on digestibility,nitrogen utilisation and milk and blood variables in lactating dairy cows fed a diet with a negative rumen nitrogen balance

The aim of the present experiment was to determine if a niacin supplementation of 6 g/d to lactating dairy cow diets can compensate negative effects of a rumen nitrogen balance (RNB) deficit. A total of nine ruminally and duodenally fistulated lactating multiparous German Holstein cows were successively assigned to one of three diets consisting of 10 kg maize silage (dry matter [DM] basis) and7 kg DM concentrate: Diet RNB– (n = 6) with energy and utilisable crude protein at the duodenum (uCP) according to the average requirement of the animals but with a negative RNB (–0.41 g N/MJ metabolisable energy [ME]); Diet RNB0 (n = 7) with energy, uCP and a RNB (0.08 g N/MJ ME) according to the average requirement of the animals and, finally, Diet NA (n = 5), which was the same diet as RNB–, but supplemented with 6 g niacin/d. Samples of milk were taken on two consecutive days, blood samples were taken on one day pre- and post-feeding and faeces and urine were collected completely over five consecutive days. The negative RNB reduced milk and blood urea content and apparent total tract digestibility of DM, organic matter (OM) and neutral detergent fibre (NDF). Also N excretion with urine, the total N excreted with urine and faeces and the N balance were reduced when the RNB was negative. Supplementation of niacin elevated plasma glucose concentration after feeding and the N balance increased. Supplementing the diet with a negative RNB with niacin led to a more efficient use of dietary N thereby avoiding the negative effects of the negative RNB on the digestibility of DM, OM and NDF.