Chemical composition,digestibility and feeding value of maize cobs

The digestibility of treated maize cobs was studied using Romney Marsh wether sheep in a 2 × 3 factorial design; maize cobs were ground through a 10- or 6-mm screen and three chemical treatments were applied to each grinding: distilled water (control); sodium hydroxide (4.5 g per 100 g cob dry matter); and Magadi soda (9.0 g per 100 g cob dry matter). Cobs were treated for 24 h using one litre of solution per kg of maize cobs.The digestion coefficient of crude protein was lowered (P< 0.01) by finer grinding of the maize cobs. Dry matter digestibility coefficients were 44.7, 54.2 and 61.6% for maize cobs treated with water, NaOH and Magadi soda, respectively. Digestibility of energy, cell walls and cellulose was increased more by Magadi soda than by NaOH. Digestibility of acid detergent fibre (ADF) was depressed (P< 0.05) by NaOH but improved (P< 0.05) by Magadi soda. Chemical treatment lowered (P< 0.01) the digestibility of crude protein from 28.0 to 17.0% (NaOH) or to 18.7% (Magadi soda). Grinding and chemical treatment of maize cobs interacted (P< 0.01) in their effects on digestibility of crude protein.Friesian cattle, grazed on a predominantly Nandi Setaria (Setaria sphacelata) and Silver Leaf Desmodium (Desmodium uncinatum) pasture, and supplemented with water-, NaOH- and Magadi soda-treated maize cobs, gained 0.41, 0.55 and 0.51 kg per day, respectively. Daily maize cob intake was higher on NaOH-treated than on water- and Magadi soda-treated cobs. Cattle on NaOH- and Magadi soda-treated cobs required more than 1 month to adapt to the cobs and show superior gain.     

Very high expander processing of maize on animal performance,digestibility and product quality of finishing pigs and broilers

The present study investigated the effect of hydrothermic maize processing and supplementation of amino acids (AA) in two experiments. In total, 60 barrows and 384 broilers were fed four diets including either unprocessed (T1), or hydrothermically processed maize, that is short- (T2), or long-term conditioned (LC) (T3), and subsequently expanded maize of the same batch. Assuming a higher metabolizable energy (ME) content after processing, the fourth diet (T4) contains maize processed as treatment T3, but AA were supplemented to maintain the ideal protein value. Performance, digestibility and product quality in both species were assessed. Results show that in pigs receiving T4 the average daily feed intake was lower compared with the other treatments, whereas no difference was observed in broilers. The T3 improved the feed conversion rate compared with T1 (P<0.10) for both species. In contrast, average daily gain (ADG) (1277 g/day for T2 and 1267 g/day for T3 v. 971 g/day for T1) was only altered in pigs. The hydrothermic maize processing increased the apparent total tract digestibility (ATTD) of dry matter, starch and ether extract after acid hydrolysis. This may be a consequence of higher ATTD of gross energy in the finishing phase for both animal species, suggesting a higher ME content in diets with processed maize. The higher ME content of diets with processed maize is supported also by measurements of product quality. Supplementation of AA in T4 enhanced the loin depth in pigs as well as the amount of breast meat in broilers. Further effects of processing maize on meat quality were the reduced yellowness and antioxidative capacity (P<0.10) for broilers, likely due to the heat damage of xanthophylls and tocopherols. Processing also increased springiness and chewiness (P<0.10) of the broilers breast meat, whereas the loin meat of pigs showed a decreased lightness and yellowness (P<0.10) in meat when hydrothermic processed maize was used (for T2, T3 and T4). LC processed maize (T3) showed the lowest springiness in pork, however the supplementation of AA in T4 did not show differences between the treatments. Shown results demonstrated positive effects of hydrothermic processing of maize on animal performance and digestibility in both species. However, effects on carcass characteristics and product quality differed. The negative effects on product quality could be partly compensated with the AA supplementation, whereas a change in meat colour and reduced antioxidative capacity was observed in all groups fed hydrothermic maize processing.     

Digestibility of timothy hay by African elephants

Two juvenile, female African elephants (Loxodonta africana) were used in summer and winter trials to determine the apparent digestibility of timothy (Phleum pratense) hay. After 12–14 days of dietary adjustment, dry matter intake and fecal excretion were quantitatively measured for 7 days. Dry matter of timothy hay contained 8.6 and 7.7% crude protein, 57.3 and 44.0% acid detergent fiber, and 6.5 and 6.4% ash during the summer and winter trials, respectively. Estimates of apparent digestibility during summer and winter, respectively, were 39 and 35% for dry matter, 43 and 32% for gross energy (GE), 45 and 30% for crude protein (CP), and 36 and 24% for acid detergent fiber (ADF). While GE and CP digestibility estimates tended (P < .09) to be greater in the summer trial, only the digestibility of ADF was different (P < .05) between summer and winter. Dry matter intake was 1.4–1.6% of body weight (BW), providing an average of 144 kcal of digestible energy per kg BW^0.75. This value is similar to that (155 kcal per kg BW^0.75) used for estimating digestible energy requirements for maintenance of light-breed horses.     

Can lantana seeds be utilized in lamb rations?

Lantana seeds contain 70.6 g crude protein, 12.8 g ether extract, 103.1 g crude fibre, 761.0 g nitrogen-free extract, 52.5 g total ash, 8.4 g calcium and 2.5 g phosphorus/kg dry matter. The replacement, by lantana seeds, of 200 g maize/kg of concentrate mixture for lambs was studied in two experiments lasting 3–4 months. The crude protein concentration in the lantana ration was lower than in the maize, and significantly (P<0.01) so in the second experiment. In the first experiment, the digestibility and intakes of dietary crude protein (DCP) and total dietary nitrogen (TDN) of the lantana group were not significantly lower. In the second experiment, dry matter and crude protein digestibility and intakes of DCP and TDN of the lantana group were significantly (P<0.01) lower than the maize group. Even after adjustment for mean protein concentration in the diets, the intakes of DCP (P<0.01) and TDN (P<0.05) in the lantana group were significantly lower. In a repeat metabolic trial also, the adjusted intakes of both DCP and TDN (P<0.01) of the lantana group were significantly lower. In spite of the depression in feed utilization, the biochemical and haematological parameters of the blood of animals in the lantana group were within the normal range. The apparent non-toxicity of lantana seeds to lambs over long-term feeding trials calls for further work on their possible utilization as a feed ingredient.     

Utilization of alkali-treated grain. 2. Utilization by steers of diets based on hay or straw and mixed with either NaOH-treated or rolled barley

In the first of three experiments, Hereford cross steers were fed ad libitum from 325 kg to slaughter at 425 kg on diets containing 50% hay and 50% rolled or NaOH-treated (30 g/kg) barley. Liveweight gain and food conversion ratios were similar for the two groups (1.24 vs. 1.42 kg/day; 7.0 vs. 7.0 kg dry matter intake/kg gain, respectively). Dry matter and organic matter digestibility was significantly higher (P < 0.01) when the diet contained rolled, rather than NaOH-treated, barley. There were no significant differences in fibre digestibility (51.2 vs. 59.1%, respectively).In the second experiment, the optimum level of NaOH was determined for the treatment of barley when given with hay. The level of NaOH required to achieve a digestibility in whole barley similar to rolled barley was 40 g NaOH/kg, i.e., approximately 10 g/kg more than when NaOH-treated barley formed the sole component of the diet. Dry matter and organic matter digestibility increased linearly as the level of NaOH applied increased (P < 0.05) and tended to peak at 40 g NaOH/kg barley. Starch digestibility also increased linearly (P < 0.001). Fibre digestibility did not vary significantly between treatments.In the third experiment, the voluntary intake of straw by steers given rolled or NaOH-treated barley at two levels of supplementation was determined. The intake of straw was slightly, but not significantly, greater when NaOH-treated rather than rolled barley was used. The digestibility of dry matter, organic matter, starch and fibre was not significantly affected by method of cereal treatment. No problems of animal health arose throughout the three experiments.     

Intake and digestion by lambs of dwarf elephant grass (Pennisetum purpureum Schum. cv. Mott) hay or hay supplemented with urea and different levels of cracked corn grain

This study was carried out to evaluate intake, digestibility, ruminal fermentation, nitrogen (N) retention and ruminal microbial protein synthesis in lambs fed dwarf elephant grass (Pennisetum purpureum Schum. cv. Mott) hay or hay supplemented with urea and 0, 5, 10 or 15 g/kg of live weight (LW) of cracked corn grain. Ten lambs (mean LW of 28 ± 0.9 kg), housed in metabolic cages, were used in a double 5 × 5 Latin Square experiment. Except fibre intake and digestibility, which was higher, the intake and digestibility of the others feed components, as well as ruminal microbial protein synthesis and N retention were lower in non-supplemented lambs. Corn supplementation increased total dry matter (DM) (P<0.05), organic matter (OM), non-structural carbohydrate (NSC) and energy intake (P<0.01) but decreased total neutral detergent fibre (aNDFom) (P<0.01) intake, as well as OM and aNDFom intake from the hay (P<0.01). Apparent DM, OM and energy digestibility, as well as OM true digestibility (OMTD) increased (P<0.01), and aNDFom digestibility decreased linearly (P<0.01) as corn supplementation increased. Total N intake was not influenced but, apparent and true N digestibility, as well as urinary N excretion decreased (P<0.01), and ruminal microbial N entering the small intestine increased linearly (P<0.01) as corn supplementation increased. However, the efficiency of ruminal microbial protein synthesis was similar for all treatments. Mean ruminal pH values and ammonia N concentrations decreased linearly (P<0.01) with level of corn supplementation. Ammonia N and amino acid, as well as peptide concentrations in ruminal fluid were quadratically related (P<0.01) with the time after feeding. Corn supplementation had a linear additive effect on total dry matter and digestible energy intake, as well as on N retention, but a linear negative effect on hay intake and on fibre digestibility. However, decreased forage digestibility by animals was probably neither related to lower ruminal pH, which values were always higher than 7.0, nor related to ruminal sugar concentrations, which were similar for all treatments.     

Simplified method for alkali treatment of low-quality roughages for use by small-holders in developing countries

The method described is a modification of the soaking procedure of Beckmann and of Torgrimsby. As the effluent NaOH solution is successively replenished and re-used many times before being discarded, pollution is minimised. Furthermore, the amounts of water and alkali consumed are smaller than with the Beckmann method, and the same container is used for all treatments and washing. The method is adaptable to small-scale farming.In Experiment 1, Cynodon hay was treated with 0, 50 or 100 kg NaOH/tonne dry matter (DM), by a modification of the Beckmann method. Significant (P < 0.01) improvements in digestibility of dry matter (DM), organic matter (OM), and cell wall constituents (CWC) were obtained, and voluntary feed intake was raised significantly (P < 0.01).In Experiment 2, both NaOH and Ca(OH)₂ treatments at 0, 50, 100 and 150 kg alkali/tonne DM of maize stover, significantly (P < 0.01) increased DM and OM digestibility, but the response was greater with NaOH. A combination of NaOH and Ca(OH)₂ treatments had no consistent effect on digestibility, but the trend was a decline in digestibility when Ca(OH)₂ was applied at high rates of 100 and 150 kg Ca(OH)₂/tonne DM. The recovery of DM increased with Ca(OH)₂ treatment, but decreased with NaOH.In Experiment 3, the treatment of maize stover with 0, 25 or 50 kg Ca(OH)₂/tonne DM, in combination with 0, 100 or 150 kg NaOH/tonne DM, significantly (P < 0.01) decreased DM, OM, and CWC digestibility below that achieved by NaOH alone.It is concluded that with the modified method an initial allowance of 100–150 kg NaOH/tonne DM of stover and replenishment of 40–60 kg NaOH/tonne DM is optimal.     

Effect of level of sodium hydroxide treatment and volume of solution on the nutritive value of maize cobs

Maize cobs were chosen as a test material as these are produced centrally in home-steads during shelling and therefore collection and transport costs are eliminated. The knowledge gained from the improvement of their nutritive value by the dry NaOH treatment method can be adapted easily.The effect of treatment rates was tested with rams in three experiments. In the first experiment, coarsely ground maize cobs were treated at 1.67, 3.33 and 5.0 kg NaOH/100 kg cobs dry matter (DM) and formed 52% of the rations on an air-dry basis. Digestibility increased significantly (P < 0.05) and a regression equation y = 51.57 + 2.28x was calculated in which y = DM digestibility, and x = kg NaOH/100 cobs DM. In the second experiment, maize cobs treated at 2.5, 5.0, 7.5 and 10.0 kg NaOH/100 kg cobs DM formed 67% of the ration and the digestibility of DM, organic matter (OM), cell wall constituents (CWC) and crude fibre (CF) were markedly increased from 2.5 to 5.0 kg NaOH treatment levels and no further responses were obtained thereafter. In the third experiment, maize cobs formed 61% of the rations and the material was treated at 0, 2.5, 5.0 and 7.5 kg NaOH. Digestibility of DM, OM, CF and energy was significantly (P < 0.05) increased at 5.0 and 7.5 kg NaOH levels. Voluntary feed intake followed the same trend, values for g DM intake per kgW^0.75 per day being 60.5, 83.3, 95.7 and 96.0 in the order of increasing NaOH treatment rates. The total digestibility DM, OM and energy intakes were more closely correlated to voluntary feed intake than to digestibility coefficients. It is concluded that 5 kg NaOH/100 kg DM is optimum for both digestibility and voluntary feed intake.The volume of NaOH solution was varied from 25 to 200 l per 100 kg DM of maize cobs in four experiments and the digestibility of DM, OM and CWC with sheep was not affected by this factor, except that the smallest volume (25 l) depressed digestion slightly, apparently because of the difficulty of getting effective mixing with small volumes. It is concluded that 50 l per 100 kg DM of maize cobs is the minimum volume.     

Effect of glycerol supplementation during early lactation on milk yield,milk composition,nutrient digestibility and blood metabolites of dairy buffaloes

This study was conducted to evaluate the effect of increasing levels of glycerol in the diet on milk yield and composition, diet digestibility and some blood metabolites of dairy buffaloes in early lactation. A total of 24 buffaloes were blocked by average milk yield, parity and BW and then randomly assigned to three treatments: control without glycerol (CON); low glycerol (LG): control plus glycerol at 150 ml/day per buffalo; and high glycerol (HG): control plus glycerol at 300 ml/day per buffalo. The experimental period lasted for 60 days. Feeding LG and HG decreased (P<0.0001) dry matter intake compared with the CON. Buffaloes supplemented with LG and HG produced more milk (P<0.01) and had a greater (P<0.0001) yield of fat-corrected milk (3.5%) than those buffaloes fed control treatment. Glycerol-supplemented buffaloes showed a positive energy status indicated by reduced concentrations of non-esterified fatty acids and β-hydroxybutyrate. Feeding LG and HG tended to increase (P⩽0.10) concentrations of milk fat, and serum total protein and globulin and significantly decreased (P⩽0.05) milk urea nitrogen and somatic cells counts (SCCs) compared to the CON group. Inclusion of LG and HG had no effect on organic matter and non-fiber carbohydrate digestion, but improved dry matter (P=0.02), CP (P=0.09), ether extract (P=0.03), NDF (P=0.07) and ADF (P=0.03) digestion.     

Evidence of genetic variability for digestive efficiency in the growing pig fed a fibrous diet

Energy digestibility in the growing pig increases with BW increase and may differ between breeds of pigs or between lines selected on criteria other than digestion. However, little is known about the variability in energy digestibility within a line or a breed of pigs, especially when fibrous diets are fed. For this purpose, 20 Large White castrated male growing pigs originating from four boars (five per boar), and three to four sows per boar, were fed a high dietary fibre (DF) diet (18% NDF) and measured over 10 consecutive weeks (30 to 95 kg BW range) for their apparent faecal energy, nitrogen and organic matter digestibility. Each week, faeces were totally collected over 5 days and the feed dry matter intake over the same days was recorded. All digestibility coefficients increased regularly (P < 0.001) over the experimental periods or with BW increase (+0.6 point/10 kg BW increase for energy); this rate of increase was not affected by boar origin (no interaction; P > 0.05). The digestibility coefficients were affected by boar origin (P < 0.005 for energy), with about 2 points for energy between the extremes (81.7% v. 79.5%), and there was no marked interaction between boar origin and period. These preliminary results suggest the possibility of selecting growing pigs for an increased digestive efficiency when fed high DF diets.     

Rumen fermentation patterns and nutrient digestion in lambs fed cottonseed meal supplemental diets

Twenty crossbred 3–4-month-old male lambs of uniform body weight were used to assess the effect of raw and processed cottonseed (Gossypium) meals (CSM) on nutrient utilisation and rumen fermentation patterns. Lambs were assigned to five dietary treatments in a completely randomised design and fed isonitrogenous and isocaloric concentrate mixtures containing 30% deoiled groundnut cake (DGNC) (control), 40% of either raw, 45 min cooked, 1% calcium hydroxide (Ca(OH)₂) or iron (1 part free gossypol (FG):0.3 parts iron) treated CSM. The concentrate mixtures were fed to meet 80% of crude protein requirements (NRC, 1985) with ad libitum access to chopped maize hay (Zea mays). A metabolic trial of 6 days duration was conducted after 135 days of feeding, and rumen liquor was collected for 2 days at its end. Incorporation of 40% raw CSM resulted in reductions (P<0.01) in the digestibility of dry matter and organic matter in comparison to control fed lambs. Cooking and Ca(OH)₂ treatment of CSM improved digestibilities of these nutrients, to levels comparable to those in control fed lambs. The ether extract (P<0.05) and energy (P<0.01) digestibilities in lambs fed Ca(OH)₂ treated CSM were higher compared to those lambs fed raw CSM diets. Acid detergent fibre and cellulose digestibilities were lower (P<0.05) on cooked and iron treated CSM fed lambs. Retention of nitrogen and energy did not differ among diets. The digestible and metabolisable energy content of the Ca(OH)₂ treated CSM incorporated diet was higher (P<0.01) than the other CSM containing diets, but similar to DGNC containing ration. Rumen pH and total volatile fatty acid concentration was similar among diets, but NH₃–N was lower (P<0.05) on the cooked CSM diets versus the control. Feeding of lambs with raw CSM amounting to 17.9% of total dry matter intake (i.e. 303 mg FG intake per day) adversely affected utilisation of nutrients and rumen fermentation. This depression was alleviated to the greatest extent by 45 min cooking and 1% calcium hydroxide treatment. Iron treatment of CSM had little overall benefit.     

Impact of fibre intake and fibre source on digestibility,gut development,retention time and growth performance of indigenous and exotic pigs

The impact of fibre level and fibre source on digestibility, gastrointestinal tract (GIT) development, total tract mean retention time (MRT) and growth performance was studied in indigenous Mong Cai (MC) and exotic Landrace × Yorkshire (LY) pigs. The diets were based on maize, rice bran, soyabean meal, fish meal and soyabean oil, and cassava residue (CR) or brewer's grain (BG) as fibrous ingredient sources in the high-fibre diets (HF) and were fed ad libitum. A low-fibre diet (LF), containing around 200 g NDF/kg dry matter (DM), was formulated without CR and BG as feed ingredients. The HF diets (HF-CR and HF-BG) were formulated to contain around 270 g NDF/kg DM. The experiment was arranged as a 2 × 3 factorial completely randomized design with six replications, and lasted 27 days. Increased dietary fibre level resulted in a reduction (P < 0.05) in average daily gain, digestibility of organic matter (OM), CP and gross energy (GE) at the ileum and in the total tract, and in MRT, and an increase (P < 0.05) in the feed conversion ratio and in the weight of the GIT (except for small intestine and caecum). The coefficients of total tract digestibility of fibre fractions were higher in HF diets than in the LF diet, with highest values for diet HF-CR, which had a high proportion of soluble non-starch polysaccharides. MC pigs had longer MRT of digesta than LY pigs (P < 0.05), resulting in higher digestibility at the ileum and in the total tract. Across diets and breeds, the total tract apparent digestibility of OM, CP and GE was positively related (R² = 0.80 to 0.84) to the MRT of solids, whereas the MRT was negatively related to the DM intake (R² = 0.60).     

Digestibility and utilisation of diets composed of wet distillers' solids or soyabean meal and supplemented with liquid lysine product for growing pigs

A digestibility and balance trial was carried out to study the nutrient digestibility and utilisation of protein and energy in wet distillers' solids derived from barley or soyabean meal. Eight growing pigs (30–72 kg liveweight) were used in an 8 × 6 cyclic change-over experimental design, in which eight experimental diets were arranged 2 × 2 × 2 factorially. The corresponding factors were the protein source (wet distillers' solids (DS) or soyabean meal (SBM)), protein supply (130 or 162 g crude protein (CP) kg⁻¹ dry matter (DM)) and liquid lysine product supplementation.DS and SBM contained 565 g and 485 g CP kg⁻¹ DM, respectively, and the respective lysine contents in CP were 39 g and 64 g per 160 g N. The liquid lysine product contained 527 g CP kg⁻¹ DM and lysine in CP 193 g per 160 g N.No differences were found in the total tract digestibility of the nutrients or energy among diets composed of DS or SBM without lysine supplementation. Those diets with liquid lysine product supplementation, however, had opposite effects on the digestibility of the diets composed of the different protein sources. Lysine supplementation improved the digestibility of ash (P < 0.001), ether extract (P < 0.05) and crude carbohydrates (CCH) (P < 0.05) in diets composed of DS and adversely impaired the digestibility of organic matter and CCH (P < 0.05) in diets composed of SBM. The calculated digestibility of CP and gross energy were respectively 91.2% and 88.3% in SBM and 90.2% and 85.0% in DS. The digestible and calculated net energy contents were respectively 18.16 MJ kg⁻¹ DM and 10.73 MJ kg⁻¹ DM for SBM and 19.31 MJ kg⁻¹ DM and 10.40 MJ kg⁻¹ DM for DS.The pigs on the diets composed of DS had higher total (P < 0.001) and urea (P < 0.01) nitrogen (N) excretion in urine and lower daily retention of N (P < 0.001) than the pigs on the diets composed of SBM. The liquid lysine product supplementation of the diets decreased the total and urea N excretion in urine (P < 0.001) and improved the daily N retention (P < 0.001). With lysine supplementation, the protein utilisation of the diets composed of DS was improved to the level of the diets composed of SBM. No differences were observed in the utilisation of energy among the diets composed of different protein sources.It is concluded that DS is highly digestible, but its protein is efficiently utilised only with lysine supplementation.     

Performance of heifers fed on diets based on NaOH-treated maize cobs and the effect of supplementary urea and source of carbohydrates

Oven drying of maize cobs treated with 5 kg NaOH/100 kg dry matter (DM) did not influence digestibility but improved voluntary feed intake. The incorporation of nitrogen in the form of urea at 0, 0.5, 1.0 and 1.5% in the diets was useful in improving the digestibility of DM, organic matter (OM) and cell wall constituents (CWC). The response was linear. In one experiment, sugarcane molasses at 20% of a diet based on NaOH-treated maize cobs was completely replaced by cassava flour, maize meal or maize bran, and these had a detrimental effect both on voluntary feed intake and digestibility. The knowledge gained in the series of experiments was used in formulating complete diets for a 63-day experiment involving 9–15-month-old growing dairy heifers. Six animals per group were assigned to control or NaOH-treated cobs diets, the mean growth rate was significantly (P < 0.01) improved from 0.412 to 0.585 kg per day and the DM consumed per unit gain was reduced from 13.0 to 11.5 kg by NaOH treatment.     

Digestibility of diets containing increasing levels of NaOH-treated or untreated wheat straw

Sodium hydroxide-treated or untreated wheat straw was included in a basal alfalfamaize diet at 0, 10, 20 and 40%. As the level of straw increased, the apparent digestibility of dry matter (DM) and organic matter (OM) by sheep, decreased linearly (P < 0.01), with a faster decrease (P < 0.05) for diets containing untreated straw. The digestibility of DM decreased by 0.22 and 0.41% and OM by 0.24 and 0.42% for treated and untreated straw diets, respectively, with each 1% increase of straw in the diets.Addition of treated straw increased (P < 0.05) digestibility of cell wall constituents (CWC), acid detergent fibre (ADF) and hemicellulose (HC). However, when untreated straw was added, the digestibility of HC was reduced, whereas the digestibility of CWC and ADF was dependent on the level of straw added. Increasing levels of NaOH-treated straw in the diets produced linear increases (P < 0.05) in digestibility of CWC, ADF and HC. However, significant (P < 0.05) linear or quadratic responses were not noted in the digestibility of CWC, ADF and HC with increasing levels of untreated straw in the diet. Apparent digestibility of crude protein was not affected by addition of either NaOH-treated or untreated straw to the diet.In general, although changes in nutrient digestibility of the basal component small, large changes in the digestibility of nutrients in the straw component were apparent and accounted for the major differences in digestibility of the diets. The absence of curvilinearity in the regression equations suggested that there were no associative effects.     

Pigs that are divergent in feed efficiency,differ in intestinal enzyme and nutrient transporter gene expression,nutrient digestibility and microbial activity

Feed efficiency is an important trait in the future sustainability of pig production, however, the mechanisms involved are not fully elucidated. The objective of this study was to examine nutrient digestibility, organ weights, select bacterial populations, volatile fatty acids (VFA’s), enzyme and intestinal nutrient transporter gene expression in a pig population divergent in feed efficiency. Male pigs (n=75; initial BW 22.4 kg SEM 2.03 kg) were fed a standard finishing diet for 43 days before slaughter to evaluate feed intake and growth for the purpose of calculating residual feed intake (RFI). Phenotypic RFI was calculated as the residuals from a regression model regressing average daily feed intake (ADFI) on average daily gain (ADG) and midtest BW^0.60 (MBW). On day 115, 16 pigs (85 kg SEM 2.8 kg), designated as high RFI (HRFI) and low RFI (LRFI) were slaughtered and digesta was collected to calculate the coefficient of apparent ileal digestibility (CAID), total tract nutrient digestibility (CATTD), microbial populations and VFA’s. Intestinal tissue was collected to examine intestinal nutrient transporter and enzyme gene expression. The LRFI pigs had lower ADFI (P<0.001), improved feed conversion ratio (P<0.001) and an improved RFI value relative to HRFI pigs (0.19 v. −0.14 SEM 0.08; P<0.001). The LRFI pigs had an increased CAID of gross energy (GE), and an improved CATTD of GE, nitrogen and dry matter compared to HRFI pigs (P<0.05). The LRFI pigs had higher relative gene expression levels of fatty acid binding transporter 2 (FABP2) (P<0.01), the sodium/glucose co-transporter 1 (SGLT1) (P<0.05), the glucose transporter GLUT2 (P<0.10), and the enzyme sucrase–isomaltase (SI) (P<0.05) in the jejunum. The LRFI pigs had increased populations of lactobacillus spp. in the caecum compared with HRFI pigs. In colonic digesta HRFI pigs had increased acetic acid concentrations (P<0.05). Differences in nutrient digestibility, intestinal microbial populations and gene expression levels of intestinal nutrient transporters could contribute to the biological processes responsible for feed efficiency in pigs.     

Botanical composition and extent of lignification affecting digestibility of wheat and oat straw and paspalum hay

Samples of 1 kg of wheat straw, oat straw and paspalum hay were separated manually into botanical fractions, and the three largest fractions of each forage were analysed chemically for cell-wall constituents, silica and nitrogen. Proportions of digested dry matter, cellulose and hemicellulose, and potential digestibility for each of these major botanical fractions were determined when chaffed samples were placed in nylon bags and incubated for 12, 24, 48, 72 and 96 h in the rumen of sheep fed on lucerno. Cross-sections of botanical fractions were stained with safranin and fast green, and proportions of lignified tissue determined by light-microscopy and planimetry.Large differences in dry-matter digestibility between wheat straw and oat straw were attributed to the different proportions of botanical fractions. Within forages, stem was the largest fraction, the most lignified and had the lowest potential digestibility. Proportions of digested dry matter from botanical fractions at 12 h were poorly correlated with lignin content of dry matter (r = 0.25) but at 72 h were negatively correlated with lignin content of dry matter (r = ?0.84, P<0.01) and with proportions of lignified tissue (r = ?0.67, P<0.05) in the respective botanical fractions. Proportions of cellulose and hemicellulose digested at 72 h were strongly correlated with lignin content of cell walls (r = ?0.90, P<0.01; r = ?0.85, P<0.01, respectively). Proportions of lignified tissues were less closely correlated with all measurements of digestibility than were proportions of lignin in cell walls determined chemically. Development of a technique for measuring intensity of lignification might enhance the value of light-microscopy measurements.     

Effects of vitreousness and particle size of maize grain on ruminal and intestinal in sacco degradation of dry matter,starch and nitrogen

We assessed the effects of vitreousness and particle size of maize grain on ruminal and intestinal in sacco degradation of dry matter, starch and nitrogen. Six maize grain (Zea mays) genotypes characterized by differing vitreousness (proportion of vitreous in total endosperm) were ground (3-mm screen; Gr, ground particles, mean particle size (MPS): 526 μm) and cracked with a roller mill using two gap width settings (CS, cracked small particles, MPS: 1360 μm; CL, cracked large particles, MPS: 2380 μm). The ruminal and intestinal in sacco degradation of dry matter, starch and nitrogen was measured on three dry Holstein cows, fitted with rumen, proximal duodenum and terminal ileum cannulas, fed maize silage ad libitum twice daily. The ruminal starch degradability and intestinal digestibility differed among genotypes (P<0.001) and decreased as particle size increased (P<0.001). For the same particle size, starch ruminal degradability decreased (P<0.05) and intestinal digestibility decreased (P<0.002) with vitreousness. Particle size and vitreousness of maize grain are efficient factors for manipulating the amount of starch escaping rumen degradation, but may be limiting for the amount of starch digested in the small intestine.