Organ mass and composition in growing dairy goat wethers fed different levels of poultry fat and protein

Small Ruminant Research 104 (2012) 104–113

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Organ mass and composition in growing dairy goat wethers fed different levels of poultry fat and protein夽 A.K. Carmichael 1 , B. Kouakou ∗ , S. Gelaye, G. Kannan, J.H. Lee, T.H. Terrill Agricultural Research Station, Fort Valley State University, Fort Valley, GA 31030, USA

a r t i c l e

i n f o

Article history: Received 26 May 2011 Received in revised form 25 August 2011 Accepted 22 September 2011 Available online 15 October 2011 Keywords: Goats High fat Organ mass

a b s t r a c t Growing castrated dairy goats (n = 20; BW = 30 ± 3.3 kg) were used in an 82 d growing experiment to assess effects of protein and fat levels on performance and splanchnic tissue mass and composition. Animals were individually housed in elevated pens (1.2 m × 1.2 m), stratified by body weight, and randomly assigned to four dietary treatments. In a second experiment, four mature dairy bucks were used in a 4 × 4 Latin square design with 21 d periods (14 d adjustment and 7 d collection) to evaluate nutrient digestibility. Diets were formulated to provide, either 2.5 Mcal/kg DM DE and 12% CP (low fat low protein = LFLP, 2.5 Mcal/kg DM DE and 18% CP (low fat high protein = LFHP), 2.9 Mcal/kg DM DE and 12% CP (high fat low protein = HFLP), or 2.9 Mcal/kg DM DE and 18% CP (high fat high protein = HFHP). The low and high fat diets contained 3 and 15% poultry fat, respectively. At the end of the 82 d growing experiment, the animals were weighed and sacrificed. Immediately after evisceration, the digestive tract segments were tied at junctions, separated, and weighed with and without digesta. The weight of the liver and other organs of the abdominal and thoracic cavities were also recorded. Blood samples were analyzed for glucose, non-esterified fatty acids, and plasma urea nitrogen. On day 14 of each period of the digestibility experiment, total urine and feces outputs were collected and weighed. These samples were composited across days for each animal (10% of daily excretion). Fecal composites were dried at 55 ◦ C for 48 h to determine dry fecal output. Dry fecal and feed samples were ground and analyzed for DM, N, NDF, ADF, EE, and ash. Urine samples were analyzed for nitrogen. Liver, small intestinal and reticulo-rumen mucosa samples from the growing experiment were analyzed for dry matter, protein, DNA and RNA. Data from the growing experiment were analyzed as a 2 × 2 factorial arrangement in a completely randomized experiment, using fat, protein and fat × protein interaction in the model. Daily DM intakes and daily urinary outputs were similar among treatments. Dry matter, nitrogen, and fiber digestibilities were not affected by dietary treatments. Goats fed low fat diets consumed more feed than those fed high fat diets but was not affected by protein or fat by protein interaction. Average daily gains were greater for animals fed the low than high fat diets. Blood glucose and NEFA were similar among treatments, but plasma urea nitrogen increased in animal fed high protein diets. There were no differences in liver, heart, lungs, kidneys, and spleen weights. Small intestine weights (full or empty), as a percent of slaughter weight (SWT), were lower for the animals fed low fat as compared to high fat diets (1.9 vs. 2.7 and 1.5 vs. 1.9 for full or empty, respectively). Small intestinal weight (% SWT) tended to

夽 This article is part of Arvis K. Carmichael’s MS thesis. ∗ Corresponding author at: Agricultural Research Station, Fort Valley State University, 1005 State University Drive, Fort Valley, GA 31030, USA. Tel.: +1 478 827 3091; fax: +1 478 825 6376. E-mail address: [email protected] (B. Kouakou). 1 Current address: The Pet Hospital of Tucker, Tucker, GA 30273, USA. 0921-4488/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.smallrumres.2011.09.046

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decrease with high protein diets. Liver DNA increased with high fat diet. Small intestinal epithelial DM contents were high (P < 0.05) in animals fed low than high fat diets. Protein concentration in small intestinal epithelium increased with high protein diets. Splanchnic tissue weights (except omasum and abomasum) were not affected in growing goats when fed diets differing in the proportion of energy coming from poultry fat. © 2011 Elsevier B.V. All rights reserved.

1. Introduction The increase in demand for goat products (Glimp, 1995; Pinkerton, 1995; McMillin and Brook, 2005) has prompted goat producers to move toward more intensive production systems with more dietary concentrate supplementation (USA). These types of enterprises require dietary formulations that will meet animal requirements mainly, in protein and energy to allow optimum growth rate. Research with other species have demonstrated a positive correlation between dietary fiber (Sun et al., 1994; Kouakou et al., 1997a; Pond et al., 1988), and energy (Kouakou et al., 1997b), and visceral organ mass and splanchnic bed energy consumption (Patil et al., 1995a,b; Goetsch and Patil, 1997; Goetsch et al., 1997). The increase in visceral tissue mass may elevate the proportion of dietary energy taken up by the gastro-intestinal tract (GIT) and liver and decrease the amount that is available for extra-splanchnic tissue metabolism. This may contribute to the lower rate of gain with the goat. Nutrient (Ferrell and Koong, 1986) and feed intake (Lobley et al., 1994) restrictions have been shown to affect liver, GIT size, and composition. Most of these studies focused on the roughage to concentrate ratio with different types of forage (legume vs. grass, or cool season vs. warm season grass) (Kouakou et al., 1997a,b). The increase in dietary energy when fat replaces a substantial amount of dietary corn and its relationship with GIT and liver mass, composition (DNA, RNA, and protein), and metabolism have not been well documented in the goat. Dietary protein and lipids (except when protected), in contrast to fiber and grains (starch), are highly digested and absorbed. The effect of dietary fat on these different parameters will vary with the level of dietary protein. The objective of this research was to assess the effect of dietary fat and protein levels on nutrient digestibility, body weight gain, and composition of the liver and gastrointestinal tract in growing castrated dairy goats.

2.2. Dietary treatments The dietary treatments consisted of two levels of poultry fat (3 and 15% poultry fat) and two levels of protein (12 and 18% CP) in a 2 × 2 factorial arrangement of treatments. The low and high fat diets contained 3% and 15% poultry fat, respectively. The diets were formulated to provide characteristics of low fat low protein (LFLP; 3% fat, 2.5 Mcal of DE/kg DM, 12% CP), low fat high protein (LFHP; 3% fat, 2.5 Mcal of DE/kg DM, 18% CP), high fat low protein (HFLP; 15% fat, 2.9 Mcal of DE/kg DM, 12% CP) or high fat high protein (HFHP; 15% fat, 2.9 Mcal of DE/kg DM, 18% CP) rations. Rations were fed once daily for 82 d at 10% above preceding days consumption after weighing and removal of orts. Feed was sampled every 7 d to construct composites. The same diets were fed to the bucks for 21 d per period (14 d adjustment and 7 d collection) in the digestibility study. The diets were formulated to provide 12 and 18% crude protein using different proportions of soybean meal in the formulation. Fat levels were achieved using 3 and 15% poultry fat and varied amounts of ground corn (Table 1). The cottonseed hull (38%) which was not delinted provided most of the fiber in the diet. 2.3. Sampling Blood samples were drawn by jugular venipuncture into vacutainer tubes (7 ml draw) containing K2 EDTA before the final weight was recorded. On day 83, all animals were harvested at the Fort Valley State University’s GSRREC. Animals, without overnight feed deprivation, were processed based on a pre-established random order to avoid the effect of waiting time. Each goat was weighed (slaughter weight, SWT) before proceeding to the stunning shoot. Animals were stunned using a captive bolt pistol followed by exsanguinations according to standard procedures. Immediately after evisceration, organs were tied at junctions, separated, and weighed. Gastrointestinal tract components, namely reticulo-rumen, omasum, abomasum, small intestine, cecum and large intestine, were weighed with (full) and without (empty) digesta. The GIT segments were washed with tap water, and residual water was removed with paper towel before weighing. Other organs and tissues, including the liver, heart, lungs, spleen, kidneys, and visceral fat were then weighed. Tissue sections of the mid-ventral area of the rumen, mid-jejunum of small intestine, and the liver were excised immediately after evisceration.

Table 1 Diet composition. Items

2. Materials and methods 2.1. Animals The protocols for this study were approved by the Institutional Animal Care and Use Committee at Fort Valley State University (Fort Valley, GA). Twenty castrated dairy (Saanen) goats (BW = 30.7 ± 6.8 kg; 10 mo. old) from the Georgia Small Ruminant Research and Extension Center (GSRREC) were selected for the 82-d feeding experiment. Animals were dewormed based on fecal egg count and individually housed in 1.2 m × 1.2 m elevated pens with free access to water. They were stratified by weight into groups with similar means ± SE. The groups were randomly assigned to dietary treatments. To evaluate digestibility, four mature dairy (Alpine and Saanen; 3 years old) bucks were used in a 4 × 4 Latin square design. Bucks were placed in individual metabolism crates and fed for 21 days per period, including 14 d adjustment and 7 d collection periods. The bucks were allowed to rest for 7 d in the loafing area after each period. During the study period, the bucks were fed the 4 experimental diets.

Ingredients, % Cottonseed hulls Ground corn Soybean meal Poultry fat TM salta Dicalcium phosphate Vitamin premixedb Calculated values CP, % Ca, % P, % Ca:P DE, Mcal/kg DM

Dietary treatment combinations LFLP

LFHP

HFLP

HFHP

38.16 41.91 13.92 3.00 0.5 2.01 0.5

38.49 27.25 28.66 3.00 0.5 1.60 0.5

38.18 27.30 16.45 15.00 0.5 2.07 0.5

38.08 12.68 31.19 15.00 0.5 2.07 0.5

12.00 0.75 0.56 1.34 2.50

18.00 0.66 0.56 1.18 2.50

12.00 0.77 0.56 1.38 2.90

18.00 0.81 0.62 1.31 2.90

a Contained >12% Zn, 10% Mn, 5% K, 2.5% Mg, 1.5% Cu, 0.3% I, 0.1% Co and 0.02% Se. b Contained 2 million IU of vitamin A, 0.4 million IU of vitamin D3 , and 230 IU of vitamin E per kg of DM.

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Table 2 Intake, digestibility and urine output in mature dairy goat bucks fed diets differing in fat and protein levels. Items

Fat levels LF

Intake, g 1151 DM 1065 OM 274 N 80 EE Ash 86 NDF 365 ADF 322 Digestibility, % 70 OM N 78 EE 43 56 Ash 47 NDF 37 ADF Urine 2.47 Volume, l 16.7 Total N, mg a

Fat × protein

Protein levels HF

SE

LP

HP

SE

LFLP

LFHP

Effecta HFLP

HFHP

SE

1020 946 213 165 74 332 272

132.3 122.3 27.5 20.5 10.1 43.6 35.7

1067 986 227 134 81 365 296

1104 1024 259 112 79 332 298

132.3 122.3 27.5 4.9 10.1 43.6 35.7

996 927 226 81 69 341 278

1306 1203 321 79 103 389 366

1139 1045 228 186 94 390 314

902 847 197 145 54 274 230

187.1 173.0 38.9 54.5 14.2 61.6 50.5

72 77 55 50 47 45

3.4 2.3 8.5 6.2 5.8 5.9

69 76 44 56 46 37

73 79 54 51 47 45

3.4 2.3 8.5 6.2 5.8 5.9

65 74 40 48 44 27

74 81 45 65 49 47

72 78 48 63 49 46

71 77 62 37 45 44

4.7 3.2 12.0 8.8 8.2 8.4

2.32 11.8

0.535 3.2

2.54 13

2.25 15

0.534 3.2

2.68 16

2.27 17

2.41 11

2.23 13

F F×P

F×P

0.756 4.5

F = fat level (3% vs. 15% poultry fat; P < 0.05); F × P and f × p = fat × protein level interaction (P < 0.05 and 0.10, respectively).

Tissue samples were individually wrapped in aluminum foil, labeled, and frozen in liquid nitrogen. Rumen fluid (150 ml) was collected from the opened rumen, strained through eight layers of cheesecloth, acidified with H2 SO4 (7.2 N; 1% by volume), and then kept frozen until analyzed for ammonia and volatile fatty acid (VFA). The carcasses were stored at 4 ◦ C for 24 h. During carcass fabrication, muscle tissues from chops/ribs were minced and later analyzed for total protein, fat, and cholesterol. Data related to carcass and meat quality have been published (Kannan et al., 2006). For the digestibility study, collection vessels for total feces and urine were introduced on day 14. Urine was collected in buckets with 10 ml of 20% (v/v) sulfuric acid to prevent ammonia loss. Urine and fecal samples were weighed and composited across days for each animal (10% of daily excretion, fresh weight basis) and stored frozen. Daily ort samples were similarly composited within treatment for individual bucks. Fecal composites were dried at 55 ◦ C for 48 h to determine dry fecal output. During collection periods, feed offered was adjusted to 90% of ad libitum intake to ensure complete consumption. 2.4. Analytical procedures Feed, orts and dry fecal samples composites were ground to pass 1 mm screen and analyzed for dry matter (DM), ash, nitrogen (N), ether extract (EE) (AOAC, 1984), neutral detergent fiber (NDF), and acid detergent fiber (ADF) (Goering and Van Soest, 1970). Cholesterol analysis was performed on loin tissue samples. Ten grams of meat sample and 150 ml of chloroform–methanol (2:1; v/v) were used for fat extraction using the procedure of Folch et al. (1957) as described by Park et al. (1991). Five ml of the lipid sample extract were used for cholesterol analysis by the modified Rudel and Morris (1973) colorimetric method. Gastrointestinal samples (50 g) were cut, weighed after removal of residual digesta, and separated into epithelial and non-epithelial components by scraping with a microscope slide. Proportion of epithelial tissues (fresh weight basis) was determined as the difference between total and non-epithelial tissue weight over total tissue sample weight. Nucleic acids and protein contents were determined on epithelium tissues. Sub-samples of liver and epithelial tissue were dried overnight at 100 ◦ C to estimate DM, and the remaining sample used for determination of ribonucleic acid (RNA), deoxyribonucleic acid (DNA) and protein concentrations. Tissue homogenates (0.5 ml) were prepared in 9 ml of icecold PBS/EDTA (pH 7.4) and analyzed for protein (Lowry et al., 1951) with BSA as standard, and for RNA and DNA analysis using colorimetric procedures with orcinol and diphenylamine respectively (Munroe and Fleck, 1966). Rumen fluid was analyzed for ammonia-N using a modified procedure of Broderick and Kang (1980) in which 0.05 ml of sample was mixed with 2.5 ml of phenol reagent and 2.0 ml of hypochlorite reagent in a

test tube. The mixture was placed in 95 ◦ C water bath for 5 min, and then, after cooling at room temperature, the samples were read on the spectrophotometer at 630 nm. Plasma samples were analyzed for urea N (PUN) using Urease/Berthelot procedure (Procedure No. 640; Sigma 310A kit; Sigma Chemical Co, St. Louis, MO) at 570 nm. Plasma non-esterified fatty acid (NEFA) levels were determined using the Acetyl-CoA Oxidase method (NEFA C, Code No. 994-75409 E; Wako Chemicals, Richmond, VA) at 550 nm. Plasma glucose concentrations were enzymatically determined using the Trinder reagent procedure (Sigma Diagnostics, Proc. No. 315; Sigma Chemical Company, St. Louis, MO, USA). The absorbance values for the metabolites were read at specific wavelengths using a Shimadzu (Model UV-3401 PC) UV-Vis Recording Spectrophotometer (Shimadzu Scientific Instruments, Inc., Columbus, MD). 2.5. Statistical analysis Data from the growing goats were analyzed as a 2 × 2 factorial arrangement in a completely randomized design experiment using fat level, protein level, and fat × protein interactions in the model by GLM procedures in SAS (1990). The digestibility data were analyzed as a 4 × 4 Latin square design using SAS. Orthogonal contrasts were developed to separate the effect of fat and protein levels. When different by ANOVA (P < 0.05), means were separated using LSD.

3. Results and discussion 3.1. Digestion trial Dry matter, organic matter, ADF and NDF intakes were not affected (P > 0.05) by dietary treatments combinations (Table 2). Jenkins (1993) reported that a decrease or no change in DM intake can occur with fat supplementation. Variability in results is due to depressed fiber digestion and or altered metabolic conditions (Chillard, 1993; Jenkins, 1993). Otaru et al. (2011) reported depression on feed intake when lactating Red Sokoto goats were supplemented with 8, 12 or 16% compared to 4% palm oil. In our study, fiber (NDF) digestibility was not affected (Table 2). These diets contained nearly 38% cottonseed hulls as fiber source which might have been enough to remove some fat from ruminal environment preventing metabolic conditions to develop and affect feed intake with the high

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Table 3 Intake, final weight, carcass component weights in growing castrated dairy goats fed diets differing in fat and protein levels. Items

Dry matter intake, g Initial weight, kg Final weight, kg Slaughter weight, kg Average daily gain, g Cold carcass weight, kg Leg circumference, cm Leg weight, kg Rack weight, kg Loin, weight, kg Shoulder weight, kg Neck weight, kg Kidney pelvic fat, g Meat protein, % Meat fat, % Cholesterol, mg/100 g Meat dry matter, % a

Fat levels

Fat × protein

Protein levels

Effecta

LF

HF

SE

LP

HP

SE

LFLP

LFHP

HFLP

HFHP

SE

717 30.9 35.5 36.7 56 16.2 33.0 5.1 3.2 3.1 3.4 1.2 843 20.8 1.3 22.6 27.6

556 30.5 30.7 31.3 2 15.1 31.0 4.4 2.5 2.6 2.9 1.1 535 21.5 1.3 27.0 27.0

50.2 2.35 2.44 2.43 0.01 1.08 0.80 0.31 0.21 0.23 0.21 0.11 223.0 0.59 0.28 3.02 0.88

627 30.6 33.4 34.1 34 15.3 32.3 4.7 2.9 2.8 3.1 1.1 871 20.5 1.1 25.0 27.7

646 30.8 32.8 33.9 25 16.0 32.4 4.8 2.8 2.9 3.2 1.2 508 21.8 1.5 24.6 26.9

50.2 2.35 2.44 2.43 0.01 1.08 0.80 0.31 0.21 0.23 0.21 0.11 223.0 0.59 0.28 3.02 0.88

693 30.7 35.6 36.8 60 14.0 33.4 5.1 3.3 3.0 3.3 1.2 1028 19.8 1.3 23.2 28.1

740 31.1 35.4 36.5 52 18.4 32.9 5.1 3.2 3.2 3.6 1.3 659 21.9 1.2 22.0 27.0

561 30.5 31.1 31.5 7.0 16.6 31.2 4.4 2.5 2.6 2.8 1.1 715 21.3 0.8 26.8 27.2

552 30.4 30.2 31.2 -2.0 13.6 31.8 4.4 2.5 2.6 2.9 1.1 356 21.7 1.8 27.2 26.8

71.0 3.32 3.46 3.44 0.01 1.53 1.14 0.44 0.30 0.33 0.30 0.16 317.0 0.83 0.39 4.30 1.25

F

F F×P f F f

F and f = fat level (3% vs. 15% poultry fat; P < 0.05 and 0.10, respectively); F × P = fat × protein level interaction (P < 0.05).

fat diets. However, loose feces where observed, particularly in the first seven days for animals fed high fat diets. This would indicate that 15% dietary fat might have caused some ruminal disturbances early in the goats consuming HFLP and HFHP diets combinations but not severe enough to affect DM intake. Typically in other ruminants (cattle and sheep) dietary fat above 6% (DM basis) decreases fiber digestion enough to decrease DM intake. Fat or ether extract intake was higher (P < 0.05) as expected in the high fat diets compared to the low fat diets. Protein level and fat × protein interaction did not influence (P > 0.05) total fat intake. There was a significant (P < 0.05) fat × protein interaction effect on total ash intake. Within high fat diets, goats fed the low protein diet consumed more ash compared to goats fed the high protein diet. But within low fat diets protein levels did not affect ash intake. At similarly high protein level, ash intake was also lower for goats fed the high fat compared to the low fat diet. Numerically, animals fed the combination of LFLP or HFHP consumed less DM compared to animals fed the LFHP or HFLP dietary combinations. These small differences in DM intake, although not statistically significant, might have influenced the total ash intake. Organic matter, nitrogen and fiber (NDF and ADF) digestibilities were not affected (P > 0.05) by dietary treatments or treatment interactions. Ash digestibility followed the same pattern of ash intake with significant (P < 0.05) fat × protein interaction effect. Ash digestibility was lower for the HFHP (37%) dietary combination than the LFHP (65%) or HFLP (64%) combination but similar to the LFLP (47%) diet. The goats used in the digestion trial were mature animals with large enough ruminal capacity to allow the coating of the fibrous digesta particles from the cottonseed hull by the fat. The adsorption of dietary fat by fibrous digesta might have preventing any adverse metabolic changes susceptible of affecting microbial activity (Jenkins, 1993). Total urinary volume and nitrogen excretion were not influenced (P > 0.05) by treatment or treatment interactions.

3.2. Growth trial 3.2.1. Intake The animals fed the low fat diets consumed more feed DM (P < 0.05) than those fed the high fat diets, but DM intake was not affected by protein levels or protein × fat level (Table 3). When dietary energy of a basal diet was increased with grain supplementation, Santra et al. (2002) reported an increase in daily DM intake by lambs. Similar results (% BW and g/kg BW0.75 ) were obtained by Mahgoub et al. (1999) at 80 d in an experiment using sheep. In the present experiment, DM intake decreased when the energy content of the diet was increased with poultry fat. In the digestion study, where the same experimental diets where fed to mature bucks, DM intakes were not affected. This finding is similar to that of Kouakou et al. (1994) in which growing steers and mature cattle consumed roughagebased diets supplemented with soybean oil. Robelin and Grey (1984) as reported in Kouakou et al. (1994) suggested higher potential for protein accretion than for fat in young steers. The capacity to deposit absorbed fatty acids in peripheral adipose tissue is minimal for these animals. Consequently, the extra energy absorbed as fat may have been converted to acetate and then oxidized. Feed intake with the high fat diets may have decreased to minimize blood concentration or oxidation of acetate in the growing goats. The high level of fat could have modified digestive tract metabolism in growing goat to partially explain the lower intake. Goats have a lower growth rate and less carcass and sub-cutaneous fat than other livestock (Park and Washington, 1993). Although goats have less body fat than other livestock of comparable age, it is more likely that mature goats will have more carcass fat than younger animals under similar nutritional conditions. Kidney pelvic fat was not affected in the growth study, suggesting that the extra energy absorbed by goats consuming the high fat diets might have been oxidized. This would have been severe enough to decrease DM intake. When increasing levels of dietary protein (8.7–17.6%) were fed to Saanen kids, feed DM intake increased from

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Table 4 Rumen ammonia nitrogen, volatile fatty acids and blood metabolites in growing dairy goat fed diets differing in fat and protein levels. Items

Volatile fatty acids Total, mM/l Acetate, % Propionate, % Isobutyrate, % Butyrate, % Isovalerate, % Valerate, % Acetate:propionate PUN, mg/dl Glucose, mg/dl NEFA, ␮equiv./l Rumen ammonia-N, mg/dl a

Fat levels LF

HF

44.7 70.3 19.8 1.9 5.1 0.47 2.4 3.76 17 76 332 12

25.7 63.6 29.0 1.8 2.8 0.66 2.1 2.36 15 77 373 12

Fat × protein

Protein levels SE 5.9 1.9 1.9 0.46 0.68 0.09 0.40 0.30 1.1 1.8 43.5 1.4

LP

HP

37.5 66.0 24.9 2.1 4.3 0.51 2.2 3.04 14 78 287 14

32.9 67.9 23.9 1.6 3.7 0.62 2.2 3.08 18 74 408 9

SE 5.85 1.89 1.81 0.46 0.68 0.09 0.40 0.30 1.1 1.8 43.5 1.4

Effecta

LFLP

LFHP

HFLP

HFHP

SE

50.6 69.4 19.1 2.4 6.3 0.50 2.3 4.00 15 77 283 14

38.9 71.3 20.5 1.4 4.0 0.43 2.4 3.51 19 75 360 10

24.5 62.6 30.7 1.7 2.3 0.51 2.2 2.09 13 79 290 15

27.0 64.6 27.3 1.9 3.4 0.81 2.0 2.64 17 74 456 8

8.28 2.67 2.56 0.65 0.96 0.13 0.57 0.43 1.5 2.5 61.5 2.0

F F F F, f × p

F P p P

F = fat level (3% vs. 15% poultry fat; P < 0.05); F × P and f × p = fat × protein level interaction (P < 0.05 and 0.10, respectively).

448 to 608 g (Negesse et al., 2000). These authors reported a decrease in DM intake when the crude protein level was lowered to 8%. However, no changes in DM intake were observed when CP levels were around or above requirement (10.5, 12.8, and 15.5%) in agreement with our results. 3.2.2. BW gain Initial body weights were similar (30.7 ± 6.8 kg), but at the end of the study, animals fed the low and high fat diets weighed 36 and 31 kg, respectively (Table 3). Fat × protein interaction did not affect final weight. Inclusion of 15% poultry fat in the diet decreased average daily gain. Goats on low fat gained more than those fed the high fat diets. There were no significant (P > 0.05) effects of protein level or fat × protein. Animals fed the HFHP dietary combination lost an average of 2 g per day. In the digestibility study, animals fed the HFHP combination consumed relatively lower total mineral (ash) than animals fed the other dietary combinations (54, 93, 103 and 69 g for HFHP, HFLP, LFHP and LFLP, respectively). It is not clear if the low mineral intake contributed to the weight loss in animals consuming the same HFHP diets in the growth study. High dietary fats have been reported to bind to dietary calcium to form calcium salt making them unavailable for absorption (Jenkins and Palmquist, 1982). Generally, protein consumed above that needed for maintenance and muscle growth is catabolized. The carbon residue is oxidized for energy and the amino group used in urea synthesis. Urea synthesis is an energy costing process (Brooks et al., 2000). Lower intake with high fat (energy) and extra protein elimination might have been responsible for the weight loss with the HFHP diet-fed goats. Average daily gain (ADG) and cold carcass weight were affected (P < 0.05) by dietary fat levels. Protein and fat × protein interaction did not (P > 0.05) have any effect on ADG and cold carcass weight. Average daily gain and cold carcass weights were greater for goats consuming the low fat compared to the high fat diets. The difference in cold carcass weights can be traced to heavier racks (P < 0.05) and shoulders (P = 0.08) for these animals (Table 3). Weights of other primal cuts were not affected by dietary treatments. These results may relate to higher DM intake for animals fed the low fat diet than those fed the high fat diets.

Meat fat, protein and DM contents, as well as carcass, kidney and pelvic fats were not affected (P > 0.05) by dietary treatments. Total cholesterol and total fat were analyzed to assess the influence of high dietary poultry fat on their concentration in the meat. They were not affected (P > 0.05) by treatments or treatment interactions. 3.2.3. Rumen ammonia and volatile fatty acids Animals fed high protein diets had lower rumen ammonia concentration than those fed the low protein diets. Fat alone or fat × protein interaction did not affect rumen ammonia (Table 4). The protein levels were increased in the diets using soybean meal, a source of ruminal degradable protein. It was expected that the high protein diets would generate higher ruminal ammonia. High ruminal ammonia nitrogen for the low protein diet cannot be explained by dry matter intake, which was not affected by protein level. Intake was higher for animals fed the low fat diet. The combination of high fat high protein (HFHP) generated a relatively lower intake (902 g) compared to the low fat high protein (1306 g). This difference generated a relatively lower protein intake for HFHP (197 g) compared to LFHP (321 g). Usually there is a direct relationship between rumen ammonia levels and plasma or blood urea nitrogen (Fernandez et al., 1988). Total VFA, proportions of acetate and propionate, as well as ratio of acetate:propionate were affected by fat level (P < 0.05) without any significant (P > 0.05) effect of protein or fat × protein interaction. Total VFA concentrations and acetate (%) decreased (P < 0.05) with the high fat diet. The decrease in total VFA was due to the lower levels of acetate and butyrate with the high fat diet. Effects of oil supplementation on total VFA production vary upon its ability to alter fiber digestion by rumen microbes. Inconsistent results due to oil supplementation have been reported. Ueda et al. (2003) with cannulated dairy cows and Sutton et al. (1983) with sheep did not see any change in total VFA production due to roughage: concentrate ratio or linseed oil supplementation. Molar proportion of propionate increased (P < 0.01) with the high fat diet. Increase in propionate with fat supplementation has been reported (Ferlay and Doreau, 1992; Tesfa, 1993). High fat supplementation has been associated with decrease in protozoa

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numbers (Tesfa, 1993; Onetti et al., 2003; Ivan et al., 2001; Ueda et al., 2003). Decrease in protozoa number is usually associated with higher propionate production (Hino et al., 1994). The combination of low acetate and high propionate for the high fat diet resulted in a lower (P < 0.01) acetate:propionate ratio. Lower acetate:propionate ratio has also been reported with high fat diet (Onetti et al., 2003). Butyrate proportion was higher (P < 0.05) for animal fed low fat (5.1% vs. 2.8%) and tended (P = 0.10) to increase with the low fat low protein dietary combination (6.3, 4.0, 2.3 and 3.4% for LFLP, LFHP, HFLP and HFHP, respectively). Increase in propionate, isovalerate and isobutyrate but decrease in butyrate were reported by Ueda et al. (2003) with cannulated dairy cows supplemented with linseed oil. Other VFA were not affected by dietary treatments or treatment interactions. 3.2.4. Plasma urea nitrogen, glucose and NEFA Plasma urea nitrogen concentrations (Table 4) were not affected (P > 0.05) by fat or fat × protein interaction, but increased (P < 0.05) with high protein diets. High PUN with the high protein diet is in agreement with results published by Sahlu et al. (1992) and Jia et al. (1995) with Angora goats. The discrepancy between the plasma urea nitrogen and the ruminal ammonia concentration may be due to the time of sampling. The blood samples were collected on the morning of day 82 and the ruminal fluid at harvest on day 83. The rumen fluid was sampled after evisceration through the opened rumen. Although the order of processing was randomized, these results from samples collected within a short period of time after evisceration cannot be compared to those in plasma obtained the previous days. Weight loss may explain the high level of plasma urea nitrogen in animal fed the high fat high protein diet. Glucose was not affected (P > 0.05) by fat level or protein alone or fat × protein interaction. Total dietary energy concentrations were close to or above requirements. The dietary requirements for the growth trial were either at or above maintenance and so glucose levels were not affected. Veen et al. (1988) did not observe any differences in glucose and NEFA concentrations in dairy cattle consuming diets with different levels of protein. Similar results were published by Sahlu et al. (1992) in Angora goats consuming different dietary proteins levels with varying degradability. Non-esterified fatty acids were not affected (P > 0.05) by fat alone, but increased (P < 0.05) with the high protein diets (Table 4). Fat × protein interaction did not affect plasma free fatty acids. Sahlu et al. (1993) did not see any effect on NEFA in response to dietary protein in three breeds of goats. Elevated plasma NEFA concentrations were reported as a source of energy for underfed goats (Kouakou et al., 1999) and in goats after transportation (Kannan et al., 2000). In our experiment, weight loss with the high protein diet might have led to lipolysis resulting in high plasma NEFA. 3.2.5. Visceral organ mass and composition Reticulo-rumen full (with digesta), empty, or as a percent of slaughter weight, was not affected (P > 0.05) by fat, protein levels or fat × protein interaction (Table 5). These diets were in the form of 62:38 concentrate to roughage

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ratio. Published reports (Sun et al., 1994; Kouakou et al., 1997a,b) suggest an increase in reticulo-rumen mass with high roughage diets in sheep. This is mainly due to greater digesta mass with high compared to low roughage diets. The diets in this experiment, which contained 38% cottonseed hull as a low digestibility fiber source, did not produce a digesta mass significantly high enough to affect the mass of the reticulo-rumen. There is no specific published report on effect of high dietary energy from fat on characteristics of the reticulo-rumen. Most of the data reported in the literature relate to high energy provided by grains or grain milling by products. Full omasum weight was affected by fat and fat × protein interaction. The weight (g) of the full omasum was lowest (P < 0.05) in animals fed the HFHP dietary combination. With similarly high protein diet, goats fed low fat had heavier full omasum compared to those fed high fat diet. But at low protein levels, fat level did not influence full omasum weight (Table 5). When expressed as a percent of slaughter weight, full omasum weight followed the same pattern. The empty omasum weight (g) was influenced by fat × protein interaction (P = 0.07) and by fat level (P < 0.05). Overall, the combination of LFHP produced the heaviest omasum (125 g) compared to LFLP (107 g), HFLP (106 g) and HFHP (96 g). The empty omasum weight (% SWT) tended to be lower in animals fed LFLP diet. Baldwin (2000) reported greater omasum epithelial and muscle fresh weight (% EBW) in lambs fed a starter diet ad libitum or restricted (to a milk-fed energy equivalent), compared to those fed milk or the same diet at maintenance. In Baldwin’s experiment, the starter diet consisted of 58% grain (corn and barley), (16.7%) alfalfa, (16.7%) soybean meal, (8.3%) molasses, and (0.3%) vitamin–mineral premix. Full abomasum weight (g, % slaughter weight) was not affected by protein or fat × protein interaction. Empty abomasum weight (g) decreased with the high fat diet. Kouakou et al. (1997b) reported greater omasum and abomasum mass after 84 d experiment in sheep fed Bermuda grass hay compared with orchard grass hay. They indicated that weights of these segments decreased with decreasing feed quality and that 64% of the variations in abomasal tissue mass were due to variation in digestible OM intake. Conversely, Baldwin (2000) did not observe any change in abomasum tissue weight (% EBW) in sheep when fed a diet ad libitum and at maintenance. The effect of the level of energy intake on abomasum weight may vary depending on the source of the energy (fat or grain) or possibly on the fermentability of the energy source, which is the main difference between dietary grain and fat. Small intestinal weight (full) and empty (% SWT) increased (P < 0.001) with the high fat diets (Table 5). The full small intestine (g) tended to increase (P = 0.08) with the high fat diets, but dietary treatments did not affect the empty weight (g) of the small intestine. These findings (% SWT) are in agreement with data (% EBW) published by Baldwin (2000) with sheep. Dietary treatments did not affect the large intestine and the cecum full or empty weight (g, and % SWT). Goetsch (1998) reported that dietary concentrate effects on absolute gut mass have been inconsistent unless expressed relative to digestible OM or energy

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Table 5 Non-carcass component weights in growing castrated dairy goats fed diets differing in Fat and protein levels. Items

Fat levels LF

Reticulo-rumen 3520 Full, g 9.8 % SWT 767 Empty, g 2.1 % SWT Omasum 196 Full, g % SWT 0.53 116 Empty, g 0.32 % SWT Abomasum 576 Full, g 1.6 % SWT 168 Empty, g 0.47 % SWT Small intestine 702 Full, g 1.9 % SWT 532 Empty, g 1.5 % SWT Large intestine 1005 Full, g 2.8 % SWT Empty, g 610 1.7 % SWT Cecum 246 Full, g 0.68 % SWT Empty, g 47 0.13 % SWT Liver, g 586 1.6 % SWT 183 Heart, g 0.51 % SWT 84 Spleen, g % SWT 0.23 645 Lungs, g % SWT 1.7 128 Kidneys, g 0.35 % SWT Visceral fat, g 1825 4.8 % SWT

Fat × protein

Protein levels

Effecta

HF

SE

LP

HP

SE

LFLP

LFHP

HFLP

HFHP

SE

3302 10.6 631 2.0

316.6 0.81 62.7 0.18

3252 9.9 681 2.0

3571 10.5 717 2.1

317.0 0.81 62.7 0.18

3394 9.8 701 1.9

3647 9.9 833 2.3

3111 10.1 660 2.1

3495 11.1 602 1.9

447.7 1.10 88.7 0.25

138 0.45 101 0.33

14.0 0.03 5.0 0.02

179 0.53 107 0.32

155 0.45 111 0.33

14.0 0.03 5.0 0.02

187 0.50 107 0.29

205 0.56 125 0.35

170 0.55 106 0.34

105 0.34 96 0.31

19.8 0.04 7.1 0.02

509 1.7 141 0.46

56.4 0.16 9.3 0.03

545 1.6 145 0.44

540 1.6 163 0.49

56.4 0.16 9.3 0.03

563 1.6 156 0.44

589 1.6 181 0.51

528 1.7 135 0.44

490 1.6 146 0.47

79.7 0.22 13.2 0.04

839 2.7 584 1.9

52.0 0.11 27.4 0.07

818 2.5 564 1.7

722 2.2 552 1.7

51.6 0.12 27.4 0.07

744 2.0 549 1.5

659 1.8 515 1.5

893 2.9 578 1.9

784 2.5 589 1.9

72.9 0.17 38.7 0.09

933 3.0 535 1.7

61.3 0.14 38.2 0.07

1020 3.0 584 1.7

918 2.7 562 1.7

61.3 0.14 38.2 0.07

1023 2.8 607 1.7

987 2.7 613 1.7

1017 3.3 560 1.8

850 2.70 510 1.6

86.7 0.20 54.0 0.09

226 0.66 50 0.15 545 1.6 162 0.48 79 0.23 578 1.7 114 0.34 1921 5.4

250 0.75 46 0.14 546 1.6 179 0.54 77 0.23 583 1.7 127 0.38 1334 3.8

246 0.78 48 0.16 492 1.6 166 0.53 66 0.22 551 1.8 116 0.37 1058 3.4

30.1 0.08 5.9 0.02 58.4 0.10 17.3 0.05 10.9 0.02 79.3 0.14 13.4 0.02 334.3 0.54

230 0.73 49 0.16 505 1.6 158 0.51 72 0.23 516 1.7 114 0.36 1430 4.4

21.3 0.06 4.1 0.01 41.3 0.07 12.2 0.03 7.7 0.01 56.1 0.10 9.5 0.02 236.4 0.38

21.3 0.06 4.1 0.01 41.3 0.07 12.2 0.03 7.7 0.01 56.1 0.10 9.5 0.02 236.4 0.38

239 0.64 50 0.13 571 1.6 172 0.48 80 0.22 676 1.8 116 0.32 2040 5.4

254 0.72 44 0.12 600 1.7 193 0.55 88 0.24 615 1.7 139 0.38 1610 4.2

214 0.68 50 0.17 519 1.6 151 0.48 77 0.24 480 1.5 111 0.35 1802 5.4

F, F × P F, p, F × P f×p

F

f F, p F

f

p P

a F and f = fat level (3% vs. 15% poultry fat; P < 0.05 and 0.10, respectively); F × P and f × p = fat × protein level interaction (P < 0.05 and 0.10, respectively); P and p = protein level (12% vs. 18% CP; P < 0.05 and 0.10, respectively).

intake suggesting that mass of these tissues relates to the proportion of absorbed energy consumed. Weights of the liver, heart, spleen, lungs and kidney (g, and % SWT) were not influenced by fat level, protein levels or fat × protein interaction. Saintz and Bentley (1997) reported greater liver weight in beef steers fed concentrate compared to those fed roughage diets. Similar results were published by Kouakou et al. (1997b) with sheep fed moderate to low quality roughage. They reported that liver mass was greater in sheep fed legume (alfalfa) compared with grass (ryegrass wheat or Bermuda grass) hay diets. In the same study, inclusion of ground corn (increasing dietary energy) similarly increased weight of the liver. In the present experiment where a substantial proportion of the energy is provided by dietary fat, the dietary treatments did not affect liver weight, suggesting some influence of the type or source of energy being absorbed.

In the present study, visceral fat (% SWT) decreased with the high protein diets. It is not clear why goats, in contrast to other ruminants, accrete more visceral fat (Shelton, 1990) and little sub-cutaneous or intramuscular fat. Visceral fats are generally more vascularized with greater turnover rate than sub-cutaneous fats (Byers and Schelling, 1988). This may help goats maintain themselves and survive long periods of feed scarcity. The significant decrease in visceral fat when expressed as percent of slaughter weight relates to the tendency (P = 0.10) of the animals fed the high protein diets to have lower visceral fat. During weight loss, these animals mobilized visceral fat. The mobilization of visceral fat explains the tendency (P = 0.07) for higher concentrations of NEFA in these animals. 3.2.6. Epithelium, nucleic acids, and protein content Proportions of ruminal and intestinal epithelium (% fresh tissue weight) were not influenced by fat level

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Table 6 Nucleic acids, protein (mg/g of fresh tissue), RNA/DNA, protein/RNA and dry matter composition of liver, ruminal and small intestinal epithelium (mucosa) samples in growing castrated dairy goats fed diets differing in fat and protein levels. Items

Fat levels LF

Liver 32 DM, % 14 DNA, mg/g 35 RNA, mg/g Protein, mg/g 152 RNA/DNA 2.66 Protein/RNA 0.043 Ruminal mucosa 36 % 18 DM, % 13 DNA, mg/g 43 RNA, mg/g 59 Protein, mg/g RNA/DNA 3.54 0.015 Protein/RNA Small intestinal mucosa 69 % 19 DM, % 75 DNA, mg/g 37 RNA, mg/g Protein, mg/g 101 RNA/DNA 0.50 Protein/RNA 0.08

Fat × protein

Protein levels HF

SE

33 18 34 151 2.05 0.045

1.1 1.2 1.4 4.9 0.22 0.002

32 20 16 55 65 3.67 0.014 70 17 78 44 100 0.58 0.024

LP

Effecta

HP

SE

LFLP

LFHP

HFLP

HFHP

SE

32 17 35 146 2.15 0.042

33 15 35 156 2.56 0.046

1.1 1.2 1.4 4.9 0.22 0.002

33 15 36 140 2.37 0.039

32 13 35 163 2.94 0.047

32 19 34 152 1.93 0.045

34 17 35 150 2.17 0.044

1.6 1.7 1.9 7.0 0.32 0.003

2.3 1.1 1.2 8.5 2.9 0.77 0.002

36 19 14 44 63 3.15 0.016

32 19 15 54 61 4.06 0.013

2.3 1.1 1.3 8.5 2.9 0.77 0.002

36 19 13 40 60 3.11 0.017

35 18 14 45 58 3.98 0.014

36 18 15 48 66 3.20 0.016

28 21 16 62 63 4.14 0.013

3.3 1.5 1.8 12.0 4.2 1.07 0.002

2.6 0.2 4.5 3.0 2.4 0.05 0.002

63 18 72 38 99 0.54 0.028

61 18 82 44 102 0.54 0.025

2.9 0.2 4.5 3.0 2.3 0.05 0.002

67 18 71 35 101 0.50 0.030

70 19 80 39 102 0.50 0.026

70 17 74 40 98 0.58 0.025

70 17 83 48 102 0.58 0.023

3.6 0.3 6.4 4.3 3.2 0.073 0.003

F f×p f

F

a F and f = fat level (3% vs. 15% poultry fat; P < 0.05 and 0.10, respectively); f × p = fat × protein level interaction (P < 0.10); P = protein level (12% vs. 18% CP; P < 0.05).

(P > 0.05), protein (P > 0.05) or fat × protein interaction (P > 0.05). These results agree with those published by Kouakou et al. (1997a) who did not see any effect of feeding low to medium quality roughage on proportions of epithelial tissue of the ventral sac of the rumen or small intestine. Britton and Krehbriel (1993) reported that epithelial tissues are the most metabolically active components of gut tissues. Ruminal epithelial tissue development is induced by introduction of fibrous feed and production of volatile fatty acids. Baldwin (2000) observed increased epithelial and muscle wet weights (% EBW) when sheep were fed concentrate ad libitum or restricted compared to ME equivalent milk-fed animals. Epithelial tissue DM (Table 6) was higher (P < 0.01) in the small intestine of goats fed the low fat compared to animals fed the high fat diets. Dietary treatments did not affect ruminal epithelium DM. It is not clear how increase in intestinal epithelium DM without an increase in total epithelium mass will affect metabolic activity. However, any increase in protein and subsequent increase in turnover may increase energy expenditure by the epithelial tissue. Total nucleic acids and total protein and their ratios were determined to assess histological or metabolic processes involved in change of organ size. Rumen and intestinal epithelium DNA and RNA concentrations (mg/g), RNA/DNA and protein/RNA were not affected (P > 0.05) by fat level, protein level, or fat × protein interaction. These results are in agreement with mass of the reticulo-rumen and the small intestine that were not influence by dietary treatment. This indicates that there was no change in cell size (total DNA), transcriptional activity or protein synthetic capacity (RNA/DNA) and translational activity (protein/RNA). Clowes et al. (1998) reported increase in

cell size, RNA/DNA ratio in response to feed intake in skeletal muscle of lactating sow fed at 55, 100 and 125% of ad libitum consumption. Rumen and small intestinal epithelium protein concentrations (mg/g) were not affected (P > 0.05) by dietary treatments combination. Similar proportions of epithelial tissue, no change in cell size, cell protein synthetic capacity or translational activity in the small intestinal epithelium or the rumen suggest that increasing energy density through higher dietary fat does not affect total energy expenditure by gut tissues. Comparing normal and callipyge lambs muscle, Carpenter et al. (1996) reported that protein accretion leading to enlargement of muscle tissue from callipyge lamb happens without changes in translational or transcriptional activity. Higher protein accretion is often associated with higher heat production, due to the higher cost of maintenance of protein (Baldwin, 1995). Liver DNA increased with the high fat diets without any significant effect of protein or fat × protein interaction. Liver transcriptional activity tended to decrease with high fat. The high DNA and similar RNA due to fat level are responsible for the relatively lower transcriptional activity (RNA/DNA) in the liver. Protein concentration in the liver tended (P = 0.09) to be affected by fat × protein interaction. Within low fat, high protein increased protein content of the liver. But no effects of protein were observed at high fat level. At low fat level, liver protein may relate to dietary protein intake. 4. Conclusion When mature goats are fed diets containing 3 or 15% poultry fat in combination with 12 or 18% crude protein, DM intake and nutrient digestibility are not affected.

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In growing goats, consumption of the same diets significantly decreased DM intake. The combination of high fat and high protein induced body weight loss significantly enough to increase plasma NEFA. Plasma urea nitrogen increased with the high protein diets. Overall splanchnic tissue weights except (omasum and abomasum) were not affected in growing goats fed diets differing in proportion of energy coming from fat. This implies that energy concentration in goat diet can be increased by addition of poultry fat instead of grain. Although some digestive disturbances were observed at 15% poultry fat level it is clear that mature goats can tolerate higher levels of dietary fat without affecting nutrient digestibility. References Association of Official Analytical Chemists, 1984. Official Methods of Analysis, 14th ed. AOC, Washington, DC, pp. 129–130. Baldwin, R.L., 1995. Modeling Ruminant Digestion and Metabolism. Chapman and Hill Publishing Company. Baldwin, R.L., 2000. Sheep gastrointestinal development in response to different dietary treatments. Small Rumin. Res. 35, 39–47. Britton, R., Krehbriel, C., 1993. Nutrient metabolism by gut tissues. J. Dairy Sci. 76, 2125–2131. Broderick, G.A., Kang, J.H., 1980. Automated simultaneous determination of ammonia and total amino acids in ruminal fluid and in vitro media. J. Dairy Sci. 63, 64–75. Brooks, G.A., Fahey, T.H., White, T.P., Baldwin, K.M., 2000. Exercise Physiology: Human Bioenergetics and Its Applications. Mayfield Publishing Company. Byers, F.M., Schelling, G.T., 1988. In: Church, D.C. (Ed.), The Ruminant Animal Digestive Physiology and Nutrition. Prentice Hall, Englewood Cliffs, NJ 07632, p. 439. Carpenter, C.E., Rice, O.D., Crockett, N.E., Snowder, G.D., 1996. Histology and composition of muscles from normal and callipyge lambs. J. Anim. Sci. 74, 388–393. Chillard, Y., 1993. Dietary fat and adipose tissue metabolism in ruminants, pigs, and rodents: a review. J. Dairy Sci. 76, 3897–3931. Clowes, E.J., Williams, I.H., Barcos, V.E., Pluske, J.R., Cegielski, A.C., Zak, L.J., Aheme, F.X., 1998. Feeding lactating primiparous sows to establish three divergent metabolic states: II. Effect on nitrogen partitioning and skeletal muscle composition. J. Anim. Sci. 76, 1154–1164. Ferlay, A., Doreau, M., 1992. Influence of method of administration of rapeseed oil in dairy cows. 1. Digestion of nonlipid components. J. Dairy Sci. 75, 3020–3027. Fernandez, J.M., Croom Jr., W.J., Jonhson, A.D., Jaquette, R.D., Edens, F.W., 1988. Subclinical ammonia toxicity in steers: Effects on blood metabolite and regulatory hormone concentrations. J. Anim. Sci. 66, 3259. Ferrell, C.L., Koong, K.J., 1986. Influence of plane of nutrition on body composition, organ size and energy utilization of Sprague-Dawley rats. J. Nutr. 116, 2525–2535. Folch, J., Lees, M., Sloane-Stanley, G.H., 1957. A simple method for the isolation and purification of total lipids from animal tissues. J. Biol. Chem. 226, 497–509. Glimp, H.A., 1995. Meat goat production and marketing. J. Anim. Sci. 73, 291–295. Goering, H.K., Van Soest, P.J., 1970. Forage fiber analyses. In: Apparatus, Reagents, Procedures, and Some Applications. ARS, USDA Agricultural Handbook No. 379, pp. 1–20. Goetsch, A.L., Patil, A.R., 1997. Relationships among splanchnic tissue energy consumption and net flux of nutrients, feed intake, and digestibility in wethers consuming forage-based diets ad libitum. J. Appl. Anim. Res. 11, 1–18. Goetsch, A.L., Patil, A.R., Galloway Sr., D.L., Kouakou, B., Wang, Z.S., Park, K.K., Rossi, J.E., 1997. Net flux of nutrients across splanchnic tissues in wethers consuming ad libitum different grass sources and physical forms. Br. J. Nutr. 77, 769–781. Goetsch, A.L., 1998. Splanchnic tissue energy use in ruminants that consume forage-based diets ad libitum. J. Anim. Sci. 76, 2737–2746. Hino, T., Saitoh, H., Miwa, T., Kanda, M., Kamazuwa, M., 1994. Effect of aibellin, a peptide antibiotic, on propionate production in the rumen of goats. J. Dairy Sci. 77, 3426–3431. Ivan, M., Mir, P.S., Koenig, K.M., Rode, L.M., Neill, L., Entz, T., Mir, Z., 2001. Effects of dietary sunflower seed oil on rumen protozoa population

and tissue concentration of conjugated linoleic acid in sheep. Small Rumin. Res. 41, 215–227. Jia, Z.H., Sahlu, T., Fernandez, J.M., Hart, S.P., The, T.H., 1995. Effects of dietary protein level on performance of Angora and cashmereproducing Spanish goats. Small Rumin. Res. 16, 113–119. Jenkins, T.C., Palmquist, D.L., 1982. Effect of added fat and calcium on in vitro formation of insoluble fatty acid soaps and cell wall digestibility. J. Anim. Sci. 55, 957–963. Jenkins, T.C., 1993. Lipid metabolism in the rumen. J. Dairy Sci. 76, 3851–3863. Kannan, G., Terrill, T.H., Kouakou, B., Gazal, O.S., Gelaye, S., Amoah, E.A., Samake, S., 2000. Transportation of goats: effects on physiological stress responses and live weight loss. J. Anim. Sci. 78, 1450–1457. Kannan, G., Gadiyaram, K.M., Galipalli, S., Carmichael, A.K., Kouakou, B., Pringle, T.D., McMillin, K.W., Gelaye, S., 2006. Meat quality in goats as influenced by dietary protein and energy levels, and postmortem aging. Small Rumin. Res. 61, 45–52. Kouakou, B., Goetsch, A.L., Patil, A.R., Galloway Sr., D.L., Park, K.K., Johnson, Z.B., 1994. Voluntary intake and digestibility by mature beef cattle and Holstein steer calves consuming alfalfa or orchard grass hay supplemented with soybean oil and (or) corn. Arch. Anim. Nutr. 47, 131–151. Kouakou, B., Goetsch, A.L., Patil, A.R., Galloway Sr., D.L., Park, K.K., West, C.P., 1997a. Visceral organ mass in wethers consuming low tomoderate-quality grasses. Small Rumin. Res. 26, 69–80. Kouakou, B., Goetsch, A.L., Patil, A.R., Galloway Sr., D.L., Park, K.K., 1997b. Visceral organ mass in wethers consuming diets with different forages and grain levels. Livest. Prod. Sci. 47, 125–137. Kouakou, B., Gazal, O.S., Terrill, T.H., Kannan, G., Galaye, S., Amoah, E.A., 1999. Effect of plane of nutrition on blood metabolites and hormone concentration in goats. J. Anim. Sci. 77 (Suppl. 1), 267. Lobley, G.E., Connell, A., Milne, E., Newman, A.M., Ewing, T.A., 1994. Protein synthesis in splanchnic tissues of sheep offered two levels of intake. Br. J. Nutr. 71, 3–12. Lowry, O.R., Rosebrough, N.J., Faar, A.L., Randall, R.A., 1951. Protein measurement with the Folin phenol reagent. J. Biol. Chem. 193, 265–275. Mahgoub, O., Lu, C.D., Early, R.J., 1999. Effects of dietary energy density on feed intake, body weight gain and carcass chemical composition of Omani growing lambs. Small Rumin. Res. 37, 35–42. McMillin, K.W., Brook, A.P., 2005. Production practices and proceesing for value-added goat meat. J. Anim. Sci. 83, E57–E68. Munroe, H.N., Fleck, A., 1966. The determination of nucleic acid. In: Glick, D. (Ed.), Methods of Biochemical Analysis, vol. 14. Wiley Interscience, New York, NY, pp. 113–176. Negesse, T., Rodehutscord, M., Pfeffer, E., 2000. The effect of dietary crude protein level on intake, growth, protein retention, and utilization of growing male Saanen kids. Small Rumin. Res. 39, 243–251. Onetti, S.G., Shaver, R.D., McGuire, M.A., Grummer, R.R., 2003. Effect of type and level of dietary fat on rumen fermentation and performance of dairy cows fed corn silage-based diets. J. Dairy Sci. 84, 2751–2759. Otaru, S.M., Adamu, A.M., Ehoche, O.W., Makun, H.J., 2011. Effects of varying the level of palm oil on feed intake, milk yield and composition and postpartum weight changes of Red Sokoto goats. Small Rumin. Res. 96, 25–35. Park, Y.W., Kouassi, M.A., Chin, K.B., 1991. Moisture, total fat and cholesterol in goat organ and muscle meat. J. Food Sci. 56, 1191–1193. Park, Y.W., Washington, A.C., 1993. Fatty acid composition of goat organ and muscle meat of Alpine and Nubian breeds. J. Food Sci. 58, 245– 253. Patil, A.R., Goetsch, A.L., Park, K.K., Kouakou, B., Galloway Sr., D.L., West, C.P., 1995a. Influence of grass source and quality on net flux of nutrients across splanchnic tissues of sheep. Livest. Prod. Sci. 34, 49–61. Patil, A.R., Goetsch, A.L., Park, K.K., Kouakou, B., Galloway Sr., D.L., Johnson, Z.B., 1995b. Influence of grass source and legume level on net flux of nutrients across splanchnic tissues in sheep. Small Rumin. Res. 22, 111–122. Pinkerton, P., 1995. “Meat Goat Marketing in Greater New York City.” The Center for Agricultural Development and Entrepreneurship. State University of New York: Oneonta, May, pp. 1–48. Pond, W.G., Jung, H.G., Varel, V.H., 1988. Effect of dietary fiber on young genetically lean, obese, and contemporary pigs: body weight, carcass measurements, organ weights, and digesta content. J. Anim. Sci. 66, 699. Robelin, J., Grey, Y., 1984. Body composition of cattle as affected by physiological status, breed, sex, and diet. In: Gilchrest, F.M.C., Mackie, R.I. (Eds.), Herbivore Nutrition in the Subtropics and Tropics. The Science Press, Craighall, South Africa, pp. 525–548. Rudel, L.L., Morris, M.D., 1973. Determination of cholesterol using ophthalaldehyde. J. Lipid Res. 14, 364–366.

A.K. Carmichael et al. / Small Ruminant Research 104 (2012) 104–113 Sahlu, T., Fernandez, J.M., Lu, C.D., Manning, R., 1992. Dietary protein level and ruminal degradability for mohair production in Angora goats. J. Anim. Sci. 70, 1526–1533. Sahlu, T., Hart, S.P., Fernandez, J.M., 1993. Nitrogen metabolism and blood metabolites in three goat breeds fed increasing amounts of protein. Small Rumin. Res. 10, 281–292. Saintz, R.D., Bentley, B.E., 1997. Visceral organ mass and cellularity in growth-restricted and refed beef steers. J. Anim. Sci. 75, 1229–1236. Santra, A., Karim, S.A., Chaturvedi, O.H., 2002. Effect of concentrate supplementation on nutrient intake and performance of lambs of two genotypes grazing a semiarid rangeland. Small Rumin. Res. 44, 37–45. SAS, 1990. Statistical Analysis System. Shelton, M.,1990. Meat and fiber production. In: Goat Production Symposium. Fort Valley State University, GA, pp. 80–91. Sun, W., Goetsch, A.L., Foster Jr., L.A., Galloway Sr., D.L., Lewis, P.K., 1994. Effects of dietary forage level and characteristics on

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performance and internal organ mass in growing lambs. Br. J. Nutr. 71, 141–151. Sutton, J.D., Knight, R., McAllan, A.B., Smith, R.H., 1983. Digestion and synthesis in the rumen of sheep given diets supplemented with free and protected oils. Br. J. Nutr. 49, 419–432. Tesfa, A.T., 1993. Effects of rape-seed oil supplementation on digestion, microbial protein synthesis and duodenal microbial amino acid composition in ruminants. Anim. Feed Sci. Technol. 41, 313–328. Ueda, K., Ferlay, A., Chabrot, J., Loor, J.J., Chilliard, Y., Doreau, M., 2003. Effect of linseed oil supplementation on ruminal digestion in dairy cows fed diets with different forage:concentrate ratios. J. Dairy Sci. 86, 3999–4007. Veen, W.A.G., Veling, J., Bakker, Y.Tj., 1988. The influence of slowly and rapidly degradable concentrate protein on nitrogen balance, rumen fermentation pattern and blood parameters in dairy cattle. Neth. J. Agric. Sci. 36, 127.