GOAT HUSBANDRY | Feeding Management

J.E. Huston , S.P. Hart , in Encyclopedia of Dairy Sciences, 2002

Energy Feeds

Energy feeds include conventional feed grains such as maize, sorghum, oats and barley and byproducts including wheat middlings, cull beans or peas, distillers' grains, maize gluten feed, brewers' grain, hominy, various types of screenings, and beet pulp. Most byproducts should not comprise more than 25% of the ration. Some (maize gluten and beet pulp, for example) should be held to 10% or less. Fat (both plant and animal) can be used to increase energy density of the lactation ration but should not exceed about 6% of the diet. Byproducts containing fat are the most cost-effective feed ingredients to increase energy density of the diet. Fat containing byproducts and their limits in concentrate include whole cottonseed (10%) and raw or roasted soya beans (10%). Excess fat in the rumen will reduce fibre digestion.

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Introduction to cereals and pseudocereals and their production

Kurt A. Rosentrater , A.D. Evers , in Kent's Technology of Cereals (Fifth Edition), 2018

1.2.1.4 Uses

Maize is traditionally a feed grain and this continues to be an important use. However, some types, such as sweetcorn and popcorn are used primarily as human food. Food use of the main crop is also important in some countries, such as several in Africa. Elsewhere, corn grits are used in the manufacture of breakfast cereals, and cornstarch is used as a thickener in food products. Corn syrups are used as sweeteners in processed food and drinks. Recently maize has been used as a feedstock for production of biofuels including ethanol and diesel and in 2014 in the United States this use exceeded feed use (www.ers.usda.gov/topics/crops/corn/background.aspx).

The largest volume industrial process applied to maize grains is wet milling to produce starch as a main product; dry milling, to produce grits is applied to a smaller volume. In both processes the embryos, which are rich in lipid, are isolated and a product known as maize (corn) germ oil is produced by extraction. By-products of maize milling and germ oil extraction are suitable for inclusion in feed.

Maize is the largest component of global coarse grain (corn, sorghum, barley, oats, rye, millet and mixed grains) trade, generally accounting for about two-thirds of the volume over the past decade.

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Sorghum as a Feed Grain for Animal Production

Kimberly C. McCuistion , ... Robert D. Goodband , in Sorghum and Millets (Second Edition), 2019

2.2 Protein and Amino Acids

When compared with other feed grains, sorghum normally contains more crude protein than maize, but less than wheat ( Table 12.2). It is important to note that climate, agricultural management practices, and genetics can impact grain nutritive value and thus feed grains should be analyzed for nutritive value instead of using published values when formulating rations. The range of nutrient values shown in Table 12.2 illustrates this point.

Table 12.2. Sorghum Nutritive Values Compared With Other Feed Grains, With the Normal Nutrient Range Listed Below in Parentheses

Item Sorghum Maize Wheat Barley Millet
DM, % 90.2 (87.8–92.6) 88.9 (85.3–92.6) 89.0 (87.2–90.8) 89.5 (87.0–92.0) 85.6 (77.9–93.3)
TDN, % 87.4 (82.8–92.0) 88.1 (85.9–90.2) 83.8 (81.3–86.4) 80.9 (77.7–84.1) 77.4 (70.5–84.2)
CP, % 12.5 (10.6–14.3) 9.0 (7.4–10.5) 13.6 (11.0–16.3) 11.9 (9.7–14.2) 11.7 (9.4–13.9)
NDF, % 8.4 (0.0–17.3) 10.0 (7.1–13.0) 13.2 (7.6–18.9) 19.0 (12.9–25.2) 20.8 (10.3–31.3)
ADF, % 5.1 (0.5–9.7) 3.7 (2.3–5.2) 4.7 (1.5–7.9) 7.6 (4.1–11.0) 12.6 (4.2–20.9)
Ash, % 2.6 (1.7–3.5) 1.6 (0.4–2.8) 2.2 (0.9–3.5) 3.0 (2.0–3.9) 7.0 (3.4–10.6)
NEm, MJ/kg 9.22 (8.49–9.78) 9.22 (8.95–9.50) 8.58 (8.21–8.95) 8.21 (7.84–8.67) 7.84 (6.92–8.76)
NEg, MJ/kg 6.27 (5.72–6.83) 6.36 (6.18–6.64) 5.81 (5.53–6.09) 5.53 (5.17–5.90) 5.17 (4.34–6.00)
NEl, MJ/kg 8.58 (8.12–9.13) 8.67 (8.49–8.95) 8.12 (7.93–8.39) 7.84 (7.56–8.21) 7.56 (6.83–8.30)

ADF, acid detergent fiber; CP, crude protein; DM, dry matter; NDF, neutral detergent fiber; NEg, net Energy for gain; NEl, net energy for lactation; NEm, net energy for maintenance; TDN, total digestible nutrients.

Source: Dairy One Laboratory, Ithica, NY. Dairy One analyzes feed and forage samples for cattle producers in the United States.

Kafirin is the dominant fraction of sorghum protein. Kafirin constitutes some 54.1% of sorghum endosperm protein, and the lesser fractions include glutelin (33.4%), globulin (7.0%), and albumin (5.6%) (Virupaksha and Sastry, 1968). However, somewhat more recently, Taylor and Schüssler (1986) found that kafirin constituted about 44% of whole grain protein, but 68% of protein in the endosperm of sorghum. Kafirin is located in discrete protein bodies, which are embedded in the glutelin protein matrix of sorghum endosperm where both kafirin and glutelin are intimately associated with starch granules (Selle et al., 2010a). Taylor et al. (1984) found that kafirin and glutelin comprised 48.0% and 27.7% of sorghum protein, respectively, in 41 grain sorghum samples. However, kafirin, as a proportion of protein, was positively correlated (r  =   0.47; P  <   0.01) with sorghum protein concentrations; whereas, the proportion of glutelin was negatively correlated (r  =   −0.40; P  <   0.01). Therefore, as protein content of grain sorghum increases, kafirin proportions escalate, which is not favorable as Rom et al. (1992) observed that glutelin is more readily digested than kafirin using electron microscopy.

In Table 12.3, the amino acid profiles of two sorghum varieties reported by Truong et al. (2016b) are compared with ideal requirements for broiler chickens proposed by Wu (2014). Clearly, kafirin contains a paucity of basic amino acids, especially lysine, but an abundance of leucine, a branched-chain amino acid. The high leucine content in sorghum is noteworthy as excess leucine has been shown to compromise isoleucine and valine availability in poultry and leucine may also have the capacity to depress voluntary feed intakes (Morrison et al., 2007). The digestibility coefficients of 16 amino acids in broiler chickens offered diets based on either 92.7% maize or sorghum were compared by Kamisoyama et al. (2011). The digestibility of protein/amino acids in sorghum was inferior to maize as the mean true digestibility coefficient for maize was 0.945 as opposed to 0.868 for sorghum.

Table 12.3. Amino Acid Concentrations of Kafirin in Two Sorghum Varieties (MP [100.2   g/kg] or HP [109.1   g/kg]) Compared (Indexed) With Ideal Amino Acid Requirements in Diets for Broiler Chickens

Amino Acid Amino Acid Concentrations (g/100   g Protein) a Ideal Dietary Requirements b Index
Sorghum MP Sorghum HP Mean
Arginine 2.19 2.20 2.20 7.05 0.31
Histidine 1.95 1.84 1.90 2.35 0.81
Isoleucine 4.13 4.14 4.14 4.63 0.89
Leucine 15.70 15.83 15.77 7.32 2.16
Lysine 0.58 0.46 0.52 6.71 0.08
Methionine 1.17 1.18 1.18 2.82 0.42
Phenylalanine 5.59 5.72 5.66 4.03 1.40
Threonine 2.72 2.72 2.72 4.70 0.58
Valine 4.79 4.80 4.80 5.37 0.89
Alanine 10.10 10.19 10.15 6.85 1.48
Aspartic acid 6.18 6.09 6.14 4.43 1.39
Glutamic acid 24.32 24.24 24.28 11.95 2.03
Glycine 2.13 2.13 2.13 11.81 0.18
Proline 9.61 9.53 9.52 12.35 0.77
Serine 4.22 4.23 4.23 4.63 0.91
Tyrosine 4.71 4.71 4.71 3.02 1.56

HP, high protein; MP, median protein.

a
Truong et al. (2016b).
b
Adapted from Wu (2014).

Sorghum contains more of the essential amino acids threonine, tryptophan, and valine than maize on a standardized ileal digestible basis (Table 12.1). Therefore, when substituting sorghum for maize in swine rations, a greater quantity of synthetic amino acids (lysine and methionine) should be used to replace soybean meal and lower the cost of the diet. Diets formulated based on the standardized ileal digestible amino acids values will also reduce the nitrogen concentration in swine waste and benefit the environment.

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THE WORLD OF FOOD GRAINS

P.K. Zwer , in Encyclopedia of Food Grains (Second Edition), 2016

Oat for Feed Grain

Oat has been a traditional feed grain for centuries. Recent advances in corn, wheat, barley, soybean, and canola as feed grains have resulted in a worldwide decline of oat production for feed. Despite the decline, the primary use of oats remains as a feed grain. Prior to mechanization, oat was the primary feed for horses that powered farm equipment. Oat is a suitable feed for dairy and beef cattle, sheep, and horses. Although not as prevalent, oat can also be used for poultry, pigs, cats, dogs, birds, rabbits, bison, deer, and fish. In recent years, naked oat is being developed as a feed grain with improved nutritional value for markets such as weaner and grower pigs, poultry, racehorses, and birds. The following discussion centers on the traditional oat grain possessing a hull.

The nutrient value for animal feed is based on the proportion of groat to hull. The ratio varies with variety and environment. Oat groats have a higher oil or lipid content than other cereals, varying between 3% and 11%. The oil is composed primarily of unsaturated fatty acids, which can alter the fatty acid composition of the animal fat. Protein content in oat groats varies from 9% to 15% with higher lysine content than corn, wheat, and barley. Lignin is the primary fiber fraction of the hull and reduces grain digestibility in animals. Lignin content also varies in different varieties. Although hulls with high lignin reduce digestibility, varieties with lower-hull lignin content can have a beneficial effect for horses, cattle, and sheep. The hull reduces digestive problems in these animals.

The hull is a major constraint as a feed grain for poultry and pigs. It reduces digestibility resulting in low protein and poor energy. Because naked oat does not have a hull, the grain provides a good source of energy for grower and weaner pigs, broilers, and laying hens.

Overall, oat is a favorable feed for ruminants such as cattle and sheep. Oat is also the preferred feed for horses due to the palatability, digestibility, and nutritive value of the grain. Naked oat is also used for racehorses, due to the limited requirement of grain intake and the need for a good source of energy.

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Processing of Barley Grain for Food and Feed

Byung-Kee Baik , in Barley (Second Edition), 2014

BARLEY GRAIN PROCESSING FOR POULTRY FEED

Barley is a common feed grain for poultry in most European countries and Canada; it supplies the major portion of energy and nutrients in poultry diets. Even though barley is not usually a preferred grain for poultry, in some countries and regions where maize production is not feasible due to unsuitable climatic conditions, barley is still fed to poultry as the main source of feed. Compared to maize and wheat grain, barley grain contains relatively less starch and more fiber, mainly β-glucan, which together contribute to a lower energy value. The relative metabolic energy value of barley is reported to be about 85% that of maize, while the economic feed value of barley is equivalent to that of maize (Anderson 1998). The proportion of barley grain used in poultry diets in Canada to minimize the negative nutritional effects of β-glucan ranged from 10 to 40% depending on the type and growth stage of poultry (Bhatty 1993a). The antinutritive and other negative effects of β-glucan in the gastrointestinal tract of young chicks can be avoided or at least lessened by supplementation with exogenous β-glucanase of microbial origin (Hesselman et al 1981; White et al 1981; Campbell and Bedford 1992; Lázaro et al 2003, 2004).

Mechanical and Thermal Processing. For feeding poultry, barley grain is routinely processed to reduce the particle size through cracking, crushing, flaking, and grinding and also to disrupt grain integrity for the purpose of improving digestibility and availability of nutrients. Barley grain meal may be pelleted to increase the density of the feed. The particle-size reduction of barley grain is often accompanied by steaming and pressure cooking. The effects of any specific processing for particle-size reduction and heat treatments on the feeding value of barley grain are often inconsistent and inconclusive among studies, probably due to the large variations in grain characteristics of barley fed to poultry, type and age of animals, and diets fed to animals.

The advantages of pelleting, grinding, or preparing grits of barley grain to feed consumption, weight gain, and efficiency of feed utilization seem not to be evident in poultry. Sibbald (1982) reported that finely ground barley grain was lower in true metabolizable energy than coarsely ground barley grain. Hamm et al (1960) and Hussar and Robblee (1962) reported the advantages of preparing barley grain pellets, including improved feeding value in broiler chicks and turkey poults and increased feed consumption and weight gain in chicks. Pelleting barley grain increased feed consumption and body weight gain in white leghorns (Arscott et al 1962). The true metabolic energy of barley grain pellets fed to adult roosters was improved by 0.9% (Sibbald and Price 1976). On the other hand, McIntosh et al (1962) studied the usefulness of pelleting of barley grain for poultry feeding, as compared to grinding and producing grits, and observed no evident advantage of pelleting in the availability of energy. No apparent advantages of a pelleted form of processed barley grain in terms of body weight gain, feed intake, and feed-to-gain ratio over a meal-form diet were observed for broiler chicks fed hull-less waxy-starch and normal-starch barley; however, digest viscosity was reduced by 45% and starch digestibility increased by 17% with pelleted barley (Ankrah et al 1999).

The advantages and effectiveness of heat processing of barley grain and meals for feeding poultry appears not to be evident and may depend on the age of the chicks. While the weight gain of broilers was improved when they were fed diets containing 73% barley heated at 120   °C in one experiment, dietary dry matter digestibility decreased when barley grain was autoclaved at 120   °C for 30   min (Herstad and McNab 1975). Broiler chicks fed barley grain soaked for 18   h and heat-treated beforehand exhibited decreased weight gain and feed efficiency ratio (Thomke and Hellberg 1976). Heat treatment of barley certainly increases the solubility of β-glucan and other hemicelluloses, which subsequently raise the viscosity in the gastrointestinal track (Fadel et al 1988). This elevated digestive tract viscosity negatively affects the digestibility and absorption of nutrients in poultry. In contrast, Garcia et al (2003) reported the faster growth of chicks fed heat-processed barley grain compared with those fed raw barley at early ages and the loss of this positive effect of heat processing after eight days of age. García et al (2008) studied the effect of heat processing of barley grain on digestive traits and productive performance of broilers. In their study, barley grain was processed to a hammer-milled raw meal, a micronized meal (by application of moisture and 74   °C heat), or an expanded form (using 120   °C and 30 bars of pressure in a hydrothermal reactor). Heat processing of barley through micronization and extrusion improved feed intake and body weight gain in broilers of one to seven days of age, but no improvement was observed after 21   days of age. Micronized barley meal significantly increased the intestinal viscosity in chicks up to 28   days old. Expanded barley meals performed better than micronized meals, but their advantages over raw barley meals in feed performance for broiler chicks was not evident in older broiler chicks.

An extrusion process would be an effective and efficient way to modify both the physical and chemical characteristics of feeds by application of high temperature, pressure, and shear force. Feed efficiency of barley is, however, heavily affected by the extrusion conditions adopted. While dry extrusion, performed under an extrusion temperature of 90–125   °C, increased the apparent metabolizable energy of diets by 2.2% in broiler chicks (Plavnik and Sklan 1995), a significant depression of feed efficiency and apparent metabolizable energy as well as of fat and protein utilization was observed in broiler chicks fed barley meals extruded with addition of water under a barrel temperature of 120–130   °C (Vukic-Vranjes and Wenk 1995). Impaired feed utilization of extruded cereal grain in broiler diets was also reported by Vukic-Vranjes et al (1994). Excessive heat applied to barley meals during the extrusion process negatively affected the digestibility and nutritive value in broiler chicks, which parallels the poor feed efficiency of autoclaved or steamed barley meals (Thomke and Hellberg 1976).

Enzyme Supplementation. Broiler chicks require diets of high energy for rapid growth and development. Compared to maize and wheat, barley grain is relatively lower in metabolizable energy and also richer in β-glucan, which is especially undesirable for young chicks. Many attempts have been made to improve utilization and metabolizable energy of barley grain for feeding chicks. Barley grain processed through grinding, soaking in water, and then drying gave a performance similar to or even better than that of maize (Fry et al 1957). Treatments of barley grain with a commercial exogenous β-glucanase preparation of fungal and bacterial origins are well accepted as an effective way to improve weight gain of chicks and feed consumption and to decrease the incidence of sticky droppings (Hesselman et al 1982, Petterson et al 1991, Campbell and Bedford 1992). The effects of enzyme addition to poultry diets on the energy value of barley grain have been extensively studied (Rotter et al 1990; Friesen et al 1992; Ankrah et al 1999; Garcia et al 2003, 2008). It has been suggested that β-glucanase lowers the gastric viscosity of chicks fed barley and increases the absorption of nutrients (Classen et al 1985, Hesselman and Åman 1986, Edney et al 1989, García et al 2008). The delayed contacts between digestive enzymes and nutrients in the digestive tract due to the increased viscosity contributed by soluble β-glucan (White et al 1983) and the physical hindrance of β-glucan present in the cell walls for the hydrolysis of intracellular starch and protein (Hesselman and Åman 1986) are believed to be responsible for the decreased nutrient absorption. The effectiveness of β-glucanase treatment of barley grain for the improvement of its metabolizable energy and the subsequent weight gain of poultry is, however, heavily affected by the age of chicks, barley cultivar, β-glucan content, and enzyme activity (Potter et al 1965; Herstad and McNab 1975; Mannion 1981; Rotter et al 1989a,b; Rotter et al 1990). Broiler chicks fed hull-less waxy- and normal-starch barley with addition of β-glucanase exhibited improved body weight gain, feed intake, feed-to-gain ratio, and intestinal starch digestibility and reduced digesta viscosity (Ankrah et al 1999) (Table 10.12). Improved digestive traits, retention of nutrients, and broiler performance were also observed in broiler chicks fed barley diets supplemented with an enzyme complex containing both β-glucanase and xylanase (García et al 2008).

Table 10.12. Effect of Feeding Normal or Waxy Hull-less Barley as Pellets (Reground +) or Mash (–), with (+) or without (–) β-Glucanase Supplementation on Broiler Chick (21   days) Body Weight Gain, Feed Intake, and Feed Conversion a , b

Starch Type Pellet Enzyme Body Weight Gain c (g) Feed Intake c (g) Feed Conversion (Feed/Gain) c
Normal + + 615 a 1,017 ab 1.69 b
Normal + – 447 b 963 ab 2.19 a
Normal – + 677 a 1,065 a 1.58 b
Normal – – 438 b 900 b 2.08 a
Waxy + + 650 a 1,083 a 1.67 b
Waxy + – 429 b 907 b 2.12 a
Waxy – + 596 a 959 ab 1.63 b
Waxy – – 414 b 893 b 2.19 a
SEM d 29.9 32.3 0.08
a
Source: reprinted from Ankrah et al (1999); used with permission from Elsevier.
b
Means in the same column followed by different letters differ significantly (P  &lt;   0.05).
c
Analysis of variance (2   ×   2   ×   2) indicates treatment effects as follows: body weight gain, enzyme (P  &lt;   0.01); feed intake, enzyme (P  &lt;   0.01) and starch type   ×   pelleting   ×   enzyme (P  &lt;   0.05); feed conversion, enzyme (P  &lt;   0.01).
d
Standard error of mean.

Enzyme supplementation of barley grain for feeding laying hens had largely no significant effects on the feed efficiency of barley grain in regard to laying egg and egg quality characteristics (Berg 1959, 1961) and the performance of hens (Arscott and Rose 1960, Al-Bustany and Elwinger 1988, Brenes et al 1993). Benabdeljelil and Arbaoui (1994) also reported that the proportion of barley in the diet and dietary enzyme supplementation had no significant effects on egg production. In contrast, increases in egg weight, egg production, and/or feed efficiency were observed for laying hens fed barley diets supplemented with β-glucanase (Wyatt and Goodman 1993, Brufau et al 1994). The addition of a commercial enzyme preparation that contained β-glucanase, xylanase, and pectinase to a barley and sunflower meal diet for laying hens increased egg weight and the number of eggs heavier than 60   g but resulted in no significant changes in rate of lay, feed intake, and body weight gain (Francesch et al 1995).

Wettstein et al (2000) opened the door for possible uses of transgenic malt containing β-glucanase in supplementing barley diets for poultry to improve feed efficiency and alleviate antinutritional effects and sticky dropping problems. Addition of a transgenic barley malt containing a thermotolerant β-glucanase in the amount of 6.2% of the total diet to normal barley feed meals for broiler chicks improved weight gain, drastically reduced sticky droppings, and reduced the amount of soluble β-glucan in the intestines and excrements of chicks fed the normal barley by 75 and 50%, respectively (Wettstein et al 2000), in contrast to chicks fed the normal barley without addition of the transgenic barley containing β-glucanase.

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Oats: Grain-Quality Characteristics and Management of Quality Requirements

Pamela Zwer , in Cereal Grains (Second Edition), 2017

10.5.2 Feed

Oats have been a traditional feed grain for centuries. Recent advances in corn, wheat, barley, soybean and canola as feed grains have resulted in a worldwide decline of oat production for feed. Despite the decline, the primary use of oats remains as a feed grain. Oats were the primary feed for horses that powered farm equipment prior to mechanisation. Oats are used primarily as a feed for dairy and beef cattle, sheep and horses, but can also be used for cats, dogs, birds, rabbits, bison, deer and fish. Naked oats are suited as a feed for weaner and grower pigs, poultry, racehorses and birds.

The nutrient value for animal feed is based on the proportion of groat to hull. The ratio varies with variety, but the growing environment can also influence groat percent, which varies from about 60–80%. The high oil content, comprised primarily of unsaturated fatty acids, can alter the fatty-acid composition of the animal fat. High protein content, with a greater proportion of lysine compared to other cereals, is also beneficial to animals.

Lignin is the major fibre fraction of the hull; it reduces grain digestibility in animals. Lignin content also varies in different varieties with most low-lignin varieties possessing improved grain digestibility compared to high-lignin varieties. Increased grain digestibility results in faster animal-weight gain. The hull plays an important role in feed as it reduces digestive problems such as acidosis.

The hull is a major constraint as a feed grain for poultry and pigs, because non-ruminants do not possess the enzymes necessary to digest the cellulose, hemicellulose and lignin. Because naked oats do not have the hull, the grain provides a good energy source for grower and weaner pigs, broilers, laying hens and turkeys.

Oats are the preferred feed for horses due to the palatability, digestibility and nutritive value of the grain. Naked oats are also used for racehorses, because they have limited grain intake and need a good source of energy.

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Oats: characteristics and quality requirements

P. Zwer , in Cereal Grains, 2010

7.4.2 Feed

Oats have been a traditional feed grain for centuries. Recent advances in corn, wheat, barley, soybean, and canola as feed grains have resulted in a worldwide decline of oat production for feed. Despite the decline, the primary use of oats remains as a feed grain. Oats were the primary feed for horses that powered farm equipment prior to mechanisation. Oats are used primarily as a feed for dairy and beef cattle, sheep, and horses, but can also be used for cats, dogs, birds, rabbits, bison, deer, and fish. Naked oats are suited as a feed for weaner and grower pigs, poultry, racehorses and birds.

The nutrient value for animal feed is based on the proportion of groat to hull. The ratio varies with variety, but the growing environment can also influence groat percent, which varies from about 60 to 80%. The high oil content, comprising primarily unsaturated fatty acids, can alter the fatty-acid composition of the animal fat. High protein content, with a greater proportion of lysine compared to other cereals, is also beneficial to animals.

Lignin is the major fibre fraction of the hull; it reduces grain digestibility in animals. Lignin content also varies in different varieties with most low-lignin varieties possessing improved grain digestibility compared to high-lignin varieties. Increased grain digestibility results in faster animal-weight gain. The hull plays an important role in feed as it reduces digestive problems such as acidosis.

The hull is a major constraint as a feed grain for poultry and pigs, because non-ruminants do not possess the enzymes necessary to digest the cellulose, hemicellulose and lignin. Because naked oats do not have the hull, the grain provides a good energy source for grower and weaner pigs, broilers, laying hens and turkeys.

Oats are the preferred feed for horses due to the palatability, digestibility and nutritive value of the grain. Naked oats are also used for racehorses, because they have limited grain intake and need a good source of energy.

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Controlling fungal growth and mycotoxins in animal feed

M. Olstorpe , ... J. Schnürer , in Protective Cultures, Antimicrobial Metabolites and Bacteriophages for Food and Beverage Biopreservation, 2011

9.3.3 Airtight storage

Airtight storage of high moisture feed grain requires only   ~   2% of the energy consumed in high-temperature drying (Pick et al. 1989). Safe storage of grains relies on a perfectly airtight silo with a modified atmosphere, enabling storage of the cereal grain at higher MC. Respiration of both the grain and endogenous microflora reduces levels of oxygen and increases levels of carbon dioxide (Lacey and Magan 1991; Magan et al. 2003). However, the control of spoilage microorganisms depends on maintaining the modified atmosphere. Temperature fluctuations may, in turn, generate pressure fluctuations in the silo (Druvefors et al. 2002). Also, imperfect sealing and feed outtake lead to gas leakage. Feed outtakes also result in a continuously diminishing grain bulk, making it difficult for the microbial and grain respiration to sustain the modified atmosphere needed for safe storage. Deteriorative microbial development and spontaneous heating may then occur (Lacey and Magan 1991). Airtight storage is not suitable for grain intended for baking, as the gluten protein is adversely affected, and the germination capacity impaired.

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Muscle biology and meat quality – challenges, innovations, and sustainability

Stephen B. Smith , in Animal Agriculture, 2020

Beef quality and marbling

In many developed countries raising grain-fed, high-quality beef, there are two grading systems to determine the value of beef carcasses: one grading system to estimate yield; and one grading system to estimate the quality of the beef. For the U.S.A., Yield Grade, the estimate of carcass yield, is based on a calculation that incorporates carcass weight, longissimus muscle cross-sectional area (ribeye area), and subcutaneous fat thickness (reviewed 11 ). Yield Grade 1 carcasses are those with larger ribeye area and little subcutaneous fat over the 12th thoracic (greater carcass yield) and at the other extreme, Yield Grade 5 carcasses have a relatively small ribeye area and excessive subcutaneous fat (less carcass yield).

The second grading system, Quality Grade, has a greater effect on the value of beef carcasses than Yield Grade. Quality Grade is based on lean and bone maturity, lean color, and marbling score, and in large measure predicts expected palatability. Feedlot cattle bound for whole beef cuts (steaks, roasts, etc.) typically are A maturity (youthful maturity), so lean and bone maturity have little impact on Quality Grade. Likewise, lean color generally is consistent in A maturity beef carcasses. Marbling score can be highly variable, and thus has the greatest impact on Quality Grade. In A maturity cattle raised in the U.S.A., there are four Quality Grades, Standard, Select, Choice, and Prime, although the Choice and Prime Quality Grades are frequently subdivided (e.g., Choice−, Choice0, and Choice+).

Marbling is comprised of intramuscular adipocytes lodged in the perimysium between myofibers. 15,16 Intramuscular adipocytes arise from progenitor cells within the perimysial connective tissue matrix, and increase in total number and size in cattle fed grain-based diets 16–19 (Fig. 22.2).

Fig. 22.2. Intramuscular adipocytes in the M. longissimus thoracis of Angus steers at 4   months on a high-energy, corn-based diet. Cells were stained with Oil Red O to stain adipocyte cells and hematoxylin solution according to Mayer and bluing solution for nuclei. (A and B) Calf-fed cattle slaughtered at 12   months of age. (C and D) Yearling-fed cattle slaughtered at 16   months of age.

 Reprinted with permission from Brooks MA, Choi CW, Lunt DK, et al. Carcass and meat characteristics and M. longissimus thoracis histology of beef from calf-fed and yearling-fed Angus steers. Prof Anim Sci. 2011; 27:385–393.

Most feedlots in the U.S.A. have as their target United States Department of Agriculture (USDA) Choice, but a growing number of producers prefer their cattle to be fed to achieve USDA Prime. To grade USDA Choice, cattle must achieve marbling scores of Modest (6.0%–6.9% lipid in the longissimus muscle at the 12th thoracic vertebra; wet weight basis) to Moderate (8.0%–8.9% lipid). USDA Prime requires intramuscular lipid 9% or greater, and most cattle raised in the U.S.A. don't exceed 12% intramuscular lipid when raised to A maturity. At A maturity, these levels of intramuscular lipid only can be achieved if cattle are fed a grain-based finishing diet. Intramuscular adipocytes (marbling) are responsible for intramuscular lipid amounts greater than 1% (which represents phospholipids of membrane lipids).

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Veterinary Vaccines and Diagnostics

Deoki N. Tripathy , in Advances in Veterinary Medicine, 1999

I. Introduction

Pigs are efficient converters of feed grains into valuable animal protein. As a result the swine industry provides about 25% of the energy and 9% of the protein that human beings obtain from animal sources ( Pond, 1983). The industry annually provides about 30–35 kg of high-quality protein for each person in the United States. To increase production efficiency, innovative management practices have been instituted and biologicals are used to reduce disease-related losses. Moreover, swine production has changed from a large number of small farms to a relatively small number of large operations. Because of the intensive nature of these production units, losses due to contagious disease have been magnified, especially those manifested in the respiratory, reproductive, and enteric systems. To prevent diseases, swine are routinely vaccinated against common pathogens that are responsible for significant mortality, morbidity, and reduced weight gain. Some of the live vaccines, used, for example, against the viral diseases, are rotavirus, transmissible gastroenteritis virus, pseudorabies virus, and parvovirus. In spite of the availability of effective vaccines for some diseases, novel pathogens (e.g., the porcine respiratory and reproductive syndrome virus) continue to emerge and some of the attenuated virus (e.g., pseudorabies virus) vaccines can become latent.

Although the economic impact of swine diseases varies, significant losses due to infectious agents still occur. While current information on disease-related losses is not available, according to a 1986 report of the Committee on CSRS Animal Health Research Programs, major disease-related losses attributed to respiratory infections were $400 million, to reproductive disorders were $200 million, and to enteric infections were $214 million annually in 1976. In this regard, three distinct swine diseases that are viral in origin are briefly described next.

Aujeszky's disease is caused by the herpesvirus (pseudorabies virus) and is responsible for significant economic losses to the swine industry. This disease is contagious and is characterized by encephalomyelitis and inflammation of the upper respiratory tract. Mortality can reach 100% in piglets under 2 weeks of age. The respiratory form of the disease is common in growing and adult pigs. In pregnant sows, abortion, mummification of fetuses, or stillbirths can occur depending on the stage of pregnancy. Recovered or subclinically infected pigs continue to shed virus leading to persistent herd infection. The annual cost of pseudorabies for swine producers was more than $21 million in the mid-1980s (Miller et al., 1996). Most vaccines do provide clinical protection against disease but do not prevent shedding or multiplication of the virus. Thus, some animals remain carriers for variable periods and become a source of infection for susceptible animals. Therefore, it is important for vaccination to prevent or reduce virus shedding to the extent that transmission to other susceptible animals is reduced. To attenuate the virus further, several genetically engineered deletion mutants have been developed and evaluated for their ability to reduce virus shedding. The impact of such vaccines is not yet fully known. Several countries are attempting to eradicate pseudorabies virus infection in their swine populations with or without the use of vaccines. However, in certain regions feral swine harboring latent virus can still be a potential source of infection for the domestic swine. Eradication of pseudorabies virus from such a population is practically impossible.

Diarrheal disease is a common and significant problem among neonatal pigs. Economic losses in the United States due to neonatal diarrhea are estimated in excess of $200 million annually. Similar problems are encountered in other countries, such as Australia. Here, Mullan et al. (1994) estimated a loss of $260 to $330 per breeding sow in the ensuing 12 months after infection with transmissible gastroenteritis virus (TGEV). According to the National Animal Monitoring System of USDA, TGE cost the pork industry located in Iowa alone $10 million annually in 1987 and 1988 (Hill, 1989). TGEV causes a highly contagious enteric disease affecting pigs of all ages. In case of neonatal pigs, TGE is characterized by severe diarrhea, vomiting, and mortality approaching 100%. This disease is caused by a coronavirus that is shed in feces and nasal secretions. Current vaccines consisting of attenuated or inactivated TGEV are inadequate (Saif and Jackwood, 1989; Saif and Wesley, 1992).

In recent years an economically important emerging pathogen, porcine respiratory and reproductive syndrome (PRRS) virus, has been responsible for significant losses to the swine industry. Clinical signs of the disease range from inapparent infection to severe losses of more than 20% pig production and can occur in all types of swine production systems (Becker and Schwartz, 1996). PRRS virus strains of variable virulence cause reproductive and respiratory tract disease. Modified live virus vaccines against PRRS are available although a considerable amount of evidence suggests that vaccines are clearly not the entire solution to the PRRS problem. A severe form of PRRS recently emerged in Iowa, despite vaccination (Halbur and Bush, 1997).

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