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Lathyrus cicera is a grain legume that is well adapted to grow in low rainfall regions. However, it contains a neurotoxin, 3-(-N-oxalyl)-l-2,3-diaminopropionic acid (ODAP), which can cause paralysis of the lower limbs, known as "lathyrism". An experiment was conducted to measure the nutrient content and ileal digestible amino acid content of a recently-released low ODAP Lathyrus variety chalus. Chemical analyses and total tract digestibility showed that the new Lathyrus variety chalus contained 0.9 g ODAP/kg, 265 g crude protein/kg and 13.5 MJ digestible energy/kg on an as-fed basis. The ileal digestible nutrient content of chalus was measured with six grower pigs (Large White×Landrace, 43 ± 0.3 kg) fitted with a simple T-piece cannula. The chalus contained 12.9, 1.4 and 5.4 g of apparent ileal digestible lysine, methionine and threonine, respectively/kg. Standardised ileal digestible amino acid content was calculated using published endogenous amino acid losses determined in 34-kg-growing pigs under a protein-free method. The chalus contained 14.3, 1.5 and 6.0 g of standardised ileal digestible lysine, methionine and threonine, respectively/kg.

To optimize dietary protein level in relation to growth, semipurified diets with an essential amino acid profile similar to that of the soft body profile were fed for 59 days to young greenlip abalone, Haliotis laevigata (initial shell length, 15–25 mm). Animals were housed in 10-L acrylic tanks, with flow-through seawater supplied at 1 L min–1 (20 °C, salinity= 36 g L–1). Protein level of feeds ranged from 122 g kg–1 to 461 g kg–1 crude protein (CP) on an ‘as is’ basis. Second-order polynomial regression analysis of specific growth rate indicated that maximal growth occurs at 270 g kg–1 CP. The protein and energy components of the feed were estimated to have a digestibility of 71.7% and 55.6%, respectively.

1. The effects of lupin non-starch polysaccharides (NSPs) on apparent metabolisable energy (AME) and composition of digesta from broiler chickens were examined in a dose-response experiment in conjunction with a single combination of 2 commercial enzyme products known from previous studies to partially depolymerise NSPs in diets containing sorghum, casein and lupin kernel. The 7-d experiment was conducted on broiler chickens (24 to 31 d of age) in metabolism cages. 2. The basal diet used in this study contained (in g/kg) sorghum (low tannin) 800, casein 134, celite 20 and vitamins and minerals 46. The inclusion rate for each enzyme product was 0.2 g/kg. Lupin kernel isolate (containing 560 g/kg total NSPs) replaced some of the sorghum and casein. The dose rates of lupin kernel isolate (50, 100 and 150 g/kg) were equivalent to dietary inclusion rates of 80, 160 and 240 g/kg, approximately, of untreated lupin kernel from Lupinus angustifolius cultivar Gungurru. 3. Inclusion of lupin kernel isolate in the diet depressed AME and bird performance, and raised ileal viscosity and excreta moisture, in a dose-dependent manner. 4. A combination of 2 proprietary enzyme products improved dietary AME by 0.3 MJ/kg dry matter. Enzymes reduced excreta moisture when inclusion of lupin kernel isolate was 50 g/kg (equivalent to lupin kernel at 80 g/kg, approximately) but not at higher inclusions. 5. Food enzymes partially depolymerised some insoluble NSPs in lupin kernel isolate, which increased ileal viscosity and soluble NSP content of digesta. 6. It was concluded that development of appropriate exogenous enzyme products could lead to lupin NSPs being used as an energy source for poultry.

Ninety male crossbred pigs were allocated at 30 kg live weight to a 6 5 factorial experiment involving six diets and five levels of feeding where average daily intakes were 1.11, 1.36, 1.67, 1.90 kg and ad libitum between 30 and 60 kg live weight. The control diet contained predominantly animal protein sources, another four diets contained 350 g/kg of either kernels or seeds of either L. angustifolius cv. Gungurru or L. albus cv. Kiev while the remaining diet contained 350 g/kg of peas. All diets were formulated to contain 15.3 MJ DE/kg and 0.7 g available lysine/MJ DE to ensure that dietary protein was adequate. Six estimates of the digestibility of each protein source were determined by the total faecal collection method. The digestible energy contents (SE) of L. angustifolius seed and kernel, L. albus seed and kernel and peas were 15.81 (0.18), 16.85 (0.76), 16.84 (0.34), 17.70 (0.47) and 14.98 (0.15) MJ/kg air dry, respectively. All pigs were killed at 60 kg live weight and the dressing percentage of pigs given L. angustifolius and L. albus diets were 2.6 and 4.7 units lower than the mean dressing percentage of pigs given the other diets. The major factors contributing to this reduction in dressing percentage when lupins were offered to pigs were gut fill and differences in intestinal weight. The relative energy value of the protein sources was assessed by comparing the relationship between the rates of energy deposition in the empty body and DE intake for the diets. The response of energy deposition to energy intake was similar for kernel and seed for both L. angustifolius and L. albus and thus data for kernel and seed were consolidated for both types of lupins. The respective linear relationships between energy deposited in the empty body (E, MJ/day)

In their raw, unprocessed form, lupins have many desirable characteristics for feeding both ruminants and single-stomached animals. An emphasis on these desirable characteristics when formulating diets, combined with an advanced knowledge of how components of lupins can influence nutritional value, will ensure they make a cost-effective contribution to livestock diets. The main lupin species used in livestock diets include Lupinus albus, L. angustifolius and L. luteus. Supplementation of ruminant diets with lupins has been shown to have many positive effects in terms of growth and reproductive efficiency, comparable with supplements of cereal grain. The true value of lupins in ruminants, however, can only be determined following a better definition of animal requirements and a closer match of ration specifications. Pigs can effectively utilize L. angustifolius and L. luteus, but detailed research has yet to reveal the reason for poor utilization of diets containing L. albus. Poultry can tolerate high levels of lupins in their diets but levels are often restricted to avoid problems associated with excess moisture in the excreta. Variable responses to enzymes have been observed when attempting to rectify this problem. Lupins have unique carbohydrate properties characterized by negligible levels of starch, high levels of soluble and insoluble NSP, and high levels of raffinose oligosaccharides, all of which can affect the utilization of energy and the digestion of other nutrients in the diet. In addition to carbohydrates, an understanding of lupin protein, lipid and mineral composition together with a knowledge of potential anti-nutritional compounds is required if the use of this legume is to be optimized.

Two growth experiments were conducted to determine the effect of heat on the utilization of ileal-digestible lysine from field peas (Pisum sativum cultivar Dundale) fed to growing pigs. Five lysine-deficient diets (0.36 g ileal-digestible lysine/MJ digestible energy (DE)) were formulated using raw field peas, and field peas heated to either 110°, 135°, 150°, or 165° for 15 min respectively in a forced-air dehydrator. Additional diets were formulated with supplements of free lysine to verify that lysine was limiting in the diets containing the raw peas, and peas heated to 150° or 165°. The growth performance and retention of ileal-digestible lysine by pigs given the diets was determined over the 20–45 kg growth phase. Heat had a significant quadratic effect (P < 0.01) on growth rate, with responses declining from 543 g/d with pigs given the raw peas, to 407 g/d for those given the peas heated to 165°. Similarly, crude protein deposition declined in a quadratic manner (P < 0.001) from 76 to 36 g/d for pigs fed on raw peas and peas heated to 165° respectively. Retention of ileal-digestible lysine was 0.85 in the pigs given the raw field peas and declined in a quadratic manner (P < 0.001) with the application of heat to 0.48 in those pigs given the peas heated to 165°. Pigs fed on field peas heated to 165° had increased (P < 0.05) liver weights. The results indicate that heat applied to protein concentrates, even at mild temperatures, renders lysine in a form that is apparently absorbed but inefficiently utilized by the growing pig. Consequently, ileal digestibility values for lysine in heat-processed meals are unsuitable for diet formulations.

Three experiments were conducted to examine the effect of heating field peas (Pisum sativum cultivar Dundale) on (1) proximate analysis and total amino acid composition, (2) ileal and faecal digestibilities of amino acids, and (3) digestible energy content. Alternative techniques for assessing ileal and faecal digestibilities and digestible energy respectively, were also investigated. Forced-air dehydrators were used to heat field peas at temperatures of 110°, 135°, 150° or 165°. In the first experiment the apparent ileal and faecal digestibilities of amino acids and the faecal digestibility of energy in the raw and heated field peas were determined using pigs fitted with ‘T’ -shaped cannulas. In the second, apparent ileal digestibility of amino acids and the faecal digestibility of energy were determined using the direct ileal and rectal sampling technique. This involved a single collection of digesta and faeces from the digestive tract of the pig while it was anaesthetized. The faecal digestibilities of amino acids and energy were determined using total faeces collection in the third experiment. In all experiments the respective field-pea treatments comprised 400 g/kg sugar-based diets and were the only source of amino acids. Heat significantly decreased the lysine (14.6–8.7 g/kg; P < 0.001), cystine (3.2–2.6 g/kg; P < 0.01) and arginine (16.7–14.5 g/kg; P < 0.05) contents of the heated peas. The ‘reactive’ lysine content of the field peas, as measured using the Silcock technique, was decreased by 0.11 and 0.30 with the application of heat at 150° and 165° respectively. Heat treatments did not alter the ileal digestibility of most amino acids. Only aspartic acid (0.72–0.58), glutamic acid (0.80–0.65) and the basic amino acids, lysine (0.79–0.56) and arginine (0.85–0.75), showed a significant linear decrease (P < 0.05) in ileal digestibility over the heat treatments, determined using the ileal cannulation procedure. Heating significantly (P < 0.05) decreased faecal digestibility for all amino acids. Faecal digestibility was consistently greater than ileal digestibility for the raw field peas; however, this difference decreased with heat application until faecal digestibility was equal or less than ileal digestibility at the 165° treatment. Heat linearly depressed digestible energy, diet dry-matter digestibility and diet energy digestibility. Losses in lysine, cystine and arginine are likely to be due to early and advanced Maillard reactions. Considerable binding of the remaining lysine also occurred as indicated by a decline in Silcock-reactive lysine. The results indicate that the direct ileal sampling technique is a viable alternative to the cannulation procedure for amino acids, but further method development is required to decrease the variability associated with measurements. The estimation of faecal digestibility using indigestible markers and the partial faeces collection technique was as efficient as total faeces collection. In general, ileal digestibility of amino acids showed little response to heating, however, any changes that were observed were greatest for lysine. In contrast, faecal digestibility of all amino acids was greatly reduced with increasing heat application. This response appeared to be largely due to the effect of heating on microbial degradation and synthesis of amino acids in the hind-gut, rather than a reflection of the changes within the protein induced by heating. This variable response makes faecal digestibility an unreliable estimator of amino acid ileal digestibility.

The effect of heat on the availability of lysine in field peas (Pisum sativum cultivar Dundale) was determined using the slope–ratio assay with growing pigs. The field peas were heated to 110°, 135°, 150°, or 165° for 15 min using a forced-air dehydrator. Lysine availability was significantly depressed (P < 0.05) with the application of heat, even at mild temperatures of 110°. Lysine availability values of 0.96, 0.71, 0.77, 0.56, and 0.47 were determined for the raw peas and peas heated to 110°, 135°, 150° or 165° respectively. The effect of dietary protein level on the ileal digestibility of lysine in raw field peas was determined in a second experiment to estimate true ileal digestibility. Five diets were formulated to contain 85, 105, 125, 145 and 165 g protein/kg. Increasing dietary protein from 85 to 105 g/kg resulted in a significant increase in the estimate of apparent ileal digestibility from 0.84 to 0.93. Comparisons were then able to be drawn between the ileal digestibility, availability and utilization of lysine from raw and heat-treated field peas. The results indicate that unlike ileal digestibility values, estimates of lysine availability are sensitive to heat treatment and are a close reflection of lysine utilization in heated protein concentrates. Thus, lysine availability values would be more suitable for use in diet formulations than ileal digestibility estimates when dealing with heat-processed protein concentrates.

Lupins are high in crude protein, cell wall materials, and gross energy but uncertainty about the bioavailability of nutrients and adverse effects on feed intake limit their use in the pig industry. Three experiments were conducted to determine the effect of lupins on retention time in the digestive tract by determining the average time it took for ingested polyethylene beads to pass through the digestive tract of pigs fed wheat-based diets containing various lupin species and fractions. In Expt 1, pigs were restrictively fed (1.8 kg/day) diets containing either predominantly wheat or predominantly wheat plus 400 g/kg peas or L. angustifolius seeds or kernels. The retention times of diets containing 400 g/kg of L. angustifolius seeds or kernels were significantly greater than those containing wheat alone (66.4 and 64.3 v. 48.8 h, P < 0.05, s.e.d. = 7.7 h), while that for the diet containing 400 g/kg peas was intermediate (55.8 h). In Expt 2 and 3, pigs were fed 1 of 6 wheat-based diets balanced for digestible energy (DE) and amino acid composition and containing either animal protein or 350 g/kg of peas, and L. angustifolius seeds or kernels, or L. albus seeds and kernels. Pigs were restrictively fed (1.5 kg/day) for Expt 2 or fed ad libitum for Expt 3. The mean retention time of the L. albus diets was greater than the other diets in both experiments. Feed intake and daily gain were reduced in pigs fed diets containing L. albus. Despite having lower feed intakes, pigs fed diets containing L. albus had more digesta in the stomach and small intestine at slaughter than the pigs consuming the diets not containing lupins. Appropriate physical treatment or enzymatic supplementation of L. albus diets may alleviate some of the feed intake problems.

This paper reviews the carbohydrate, protein, lipid, anti-nutritional, and physical characteristics ofgrains that determine the variability in their nutritional quality for ruminant animals. The amount, rate, and extent of starch fermentation in the rumen have been the subject of many studies, with large variation found between and within grain species. Electron microscopy scanning techniques have shown that the protein matrix limits the microbial colonisation of starch granules in some grain species, whereas in others it may be the structural carbohydrates that affect colonisation. The composition of the different fibre fractions of grains and their interaction with non-fibre carbohydrates requires investigation, since it has been shown that non-starchpolysaccharides, including neutral detergent fibre and acid detergent fibre, may not be specific enough to predict animal response to grain. Fermentation patterns of the non-starch polysaccharide components of legumes are also poorly understood and hence require further investigation. Different varieties of grain and different seasonal conditions show variation in the protein fractions of the kernel. Since these fractions display different solubility and degradation rates in the rumen, rumen solubility values cannot be generalised for grains. The variability in solubility caused by rumen flow rate and pH is a further complication. Finally, the lipid content of grains varies greatly, with high-oil grains potentially contributing to the energy level of the diet, but possibly negatively affecting rumen fermentation. Due to the degree of variability of characteristics discussed in this review, it is clear that the nutritional quality of grains cannot be assessed in a single rapid assay.