Digestibility of amino acids in corn, corn co-products, and bakery meal fed to growing pigs

Rising costs of traditional swine feeds are causing many producers to look for alternative feedstuffs to deliver nutritional value at a lower cost. The corn milling and fermentation industries, and the human food industry, create co-products which can be fed to livestock. One of these, distillers dried grains with solubles (DDGS), has been found to be suitable for inclusion in swine diets up to 30%. Other co-products have not been as extensively studied. This experiment was performed to measure the apparent (AID) and standardized (SID) ileal digestibility of crude protein and amino acids in corn gluten meal, corn gluten feed, corn germ meal, hominy feed, and bakery meal in growing pigs and to compare these values to the values observed for DDGS and corn.

Alternative feedstuffs

Hominy feed is a co-product from the dry milling industry, and consists of the hull and starchy endosperm of corn kernels. Corn gluten meal, corn gluten feed, and corn germ meal are co-products from the wet milling process, in which corn is steeped in water before being separated into its components. Corn germ meal consists of the germ after extraction of the oil. Corn gluten meal consists mainly of the gluten portion of the kernel, after the germ and bran have been removed and the starch has been mechanically separated out. Corn gluten feed consists of the bran combined with condensed solubles from the steepwater. Bakery meal is produced from waste wheat products, pasta, snack foods, baked goods, and breakfast cereals.

AA digestibility

Eight diets were prepared. Seven of the diets contained commercial yellow dent corn, DDGS, hominy feed, corn gluten meal, corn gluten feed, corn germ meal, or bakery meal as the sole source of protein and amino acids. The eighth diet contained no protein and was used to measure the basal endogenous loss of protein and amino acids. Ileal digesta were collected and analyzed for protein content, and SID was calculated by subtracting endogenous loss from the total ileal protein/amino acid output.

Corn gluten meal had the greatest (P < 0.01) AID for crude protein and all indispensable amino acids of all ingredients used in this experiment, including corn and DDGS. The mean AID for indispensable amino acids in corn gluten feed, corn germ meal, hominy feed, and bakery meal did not differ from corn or DDGS.

The SID of crude protein was greater (P < 0.01) in corn and corn gluten meal than in all other ingredients (Table 2). The SID of crude protein in DDGS, bakery meal, corn germ meal, corn gluten feed, and hominy meal did not differ from each other.

The SID of lysine in corn gluten meal and corn gluten feed was greater (P < 0.01) than in DDGS, bakery meal, corn germ meal, and hominy feed, and was the same as that of corn. For all indispensable amino acids except argininine, the SID values in corn gluten meal did not differ from those of corn. SID of indispensable amino acids in bakery meal, corn gluten meal, corn gluten feed, corn germ meal, and hominy feed was in most cases less than that in corn, but the same or greater than that in DDGS.

Key points

While values for digestibility of crude protein and amino acids in corn DDGS are known, digestibility values for other corn co-products have yet to be determined.
For most amino acids, SID in bakery meal, corn gluten meal, corn gluten feed, corn germ meal, and hominy feed is comparable to or greater than that of DDGS.
With the exception of arginine, crude protein and amino acid SID of corn gluten meal is comparable to corn.

Table 1. Apparent ileal digestibility (AID) of AA in corn, corn co-products, and bakery meal fed to growing pigs.

	Dietary treatments
Item	Corn	DDGS	BM	CGluM	CGF	CGerM	HF	SEM	P-value
CP, %	59.0^b	53.8^bc	54.1^bc	77.5^a	52.1^bc	55.2^b	47.5^c	2.36	< 0.01
Indispensable AA, %
Arg	74.1^c	65.5^d	72.3^c	83.9^a	71.7^c	81.1^ab	75.8^bc	1.77	< 0.01
His	74.9^ab	70.3^bc	66.1^c	79.6^a	70.2^bc	73.5^b	72.1^bc	1.97	< 0.01
Ile	72.1^b	69.7^bc	65.4^cd	84.2^a	70.7^bc	72.6^b	62.2^d	2.14	< 0.01
Leu	83.3^b	82.1^b	74.8^c	90.4^a	78.2^bc	76.6^c	79.3^bc	1.65	< 0.01
Lys	58.0^bc	39.2^d	39.7^d	73.6^a	64.0^ab	64.4^ab	50.6^cd	3.61	< 0.01
Met	82.3^b	79.3^bc	73.5^d	89.9^a	75.3^cd	78.6^bc	73.1^d	1.68	< 0.01
Phe	79.6^b	77.2^bc	73.4^c	88.0^a	75.9^bc	78.8^b	73.0^c	1.78	< 0.01
Thr	57.8^cde	60.6^bcd	50.6^e	78.6^a	68.4^b	63.8^bc	51.0^de	2.87	< 0.01
Trp	64.9^c	75.6^b	75.9^b	86.8^a	80.0^b	76.5^b	66.2^c	1.91	< 0.01
Val	70.3^bc	68.4^bcd	63.3^d	81.9^a	68.7^bcd	72.0^b	62.8^cd	2.2	< 0.01
Mean	74.5^b	70.8^b	71.3^b	86.0^a	72.0^b	74.1^b	68.7^b	2.27	< 0.01
Dispensable AA, %
Ala	72.9^b	70.1^b	63.0^c	84.9^a	69.5^b	68.7^bc	67.4^bc	2.25	< 0.01
Asp	62.7^b	60.7^b	52.8^c	79.2^a	58.0^bc	60.8^b	57.6^bc	2.57	< 0.01
Cys	69.8^b	67.6^bc	62.3^cd	78.0^a	58.3^d	57.4^d	67.6^bc	2.27	< 0.01
Glu	81.2^ab	77.6^bc	78.2^bc	86.1^a	72.1^d	73.8^cd	76.9^bcd	1.64	< 0.01
Gly	30.9	24.6	41	39.2	36.4	42.9	35.3	5.78	0.27
Pro	6.4^ab	-20.6^bc	45.8^a	53.2^a	7.3^ab	-44.5^c	6.6^abc	17	< 0.01
Ser	70.6^b	68.5^b	65.5^b	86.0^a	66.6^b	67.7^b	69.9^b	2.05	< 0.01
Tyr	77.6^b	76.5^bc	71.8^c	88.0^a	74.9^bc	75.2^bc	70.7^c	1.83	< 0.01
Mean	61.7^bc	53.6^c	68.1^b	77.5^a	55.5^c	53.9^c	58.5^bc	3.68	< 0.01

^a-eMeans within a row lacking a common superscript letter differ (P < 0.05).

Table 2. Standardized ileal digestibility (SID) of AA in corn, corn co-products, and bakery meal fed to growing pigs.

	Dietary treatments
Item	Corn	DDGS	BM	CGluM	CGF	CGerM	HF	SEM	P-value
CP, %	89.1^a	70.5^b	72.5^b	85.5^a	70.9^b	69.5^b	74.8^b	2.51	< 0.01
Indispensable AA, %
Arg	100.1^a	81.3^d	91.5^bc	93.7^bc	90.4^c	89.7^c	96.3^ab	1.77	< 0.01
His	83.7^a	75.5^cd	72.5^d	82.8^ab	75.9^cd	77.6^bcd	79.8^abc	1.97	< 0.01
Ile	80.9^ab	74.7^bc	71.0^c	86.4^a	76.6^bc	76.7^bc	70.8^c	2.14	< 0.01
Leu	88.0^ab	84.8^bc	78.2^e	91.3^a	82.2^cde	79.8^de	83.8^bcd	1.66	< 0.01
Lys	69.2^ab	46.0^d	48.4^cd	78.7^a	68.8^ab	68.4^b	58.8^bc	3.61	< 0.01
Met	86.2^ab	81.6^bc	76.5^d	90.6^a	78.8^cd	80.8^cd	77.0^cd	1.68	< 0.01
Phe	85.9^ab	81.1^bc	77.7^c	89.4^a	81.2^bc	82.0^bc	79.2^c	1.78	< 0.01
Thr	74.9^ab	69.5^bc	62.1^c	83.5^a	75.2^ab	71.3^b	65.8^bc	2.87	< 0.01
Trp	83.9^bc	82.6^bc	83.1^bc	91.8^a	87.5^ab	81.4^c	82.4^bc	1.91	< 0.01
Val	80.1^ab	73.9^bc	69.8^c	84.9^a	74.9^bc	76.0^bc	71.7^c	2.2	< 0.01
Mean	84.9^ab	76.7^c	78.5^bc	88.6^a	78.7^bc	78.9^bc	78.0^bc	2.27	< 0.01
Dispensable AA, %
Ala	86.6^ab	77.8^c	73.0^c	87.8^a	77.9^c	75.8^c	79.3^bc	2.25	< 0.01
Asp	77.2^ab	68.1^c	62.2^c	83.2^a	66.4^c	66.4^c	68.8^bc	2.57	< 0.01
Cys	79.6^ab	73.4^bc	69.0^cd	81.0^a	65.2^d	64.1^d	76.1^abc	2.27	< 0.01
Glu	87.7^a	81.8^bc	81.8^bc	87.6^a	77.1^c	77.8^bc	82.9^ab	1.64	< 0.01
Gly	107.4^a	64.8^d	88.7^bc	66.5^d	76.2^cd	68.6^d	97.1^ab	5.78	< 0.01
Pro	193.3^a	86.4^c	158.2^ab	97.2^c	130.9^bc	98.9^c	190.2^a	14.51	< 0.01
Ser	85.1^ab	76.9^cd	75.6^d	89.7^a	77.1^cd	75.1^d	82.4^bc	2.05	< 0.01
Tyr	84.8^ab	81.1^bc	77.0^c	89.6^a	81.0^bc	79.4^bc	77.8^c	1.83	< 0.01
Mean	103.3^a	77.8^d	94.1^ab	83.6^bc	83.5^cd	76.2^d	95.6^ab	3.7	< 0.01

^a-eMeans within a row lacking a common superscript letter differ (P < 0.05).

This research report is based on unpublished research by F. N. Almeida and H. H. Stein.

Keywords:

Distillers dried grains with solubles, Corn gluten feed, Corn gluten meal, Hominy feed, Bakery meal, Corn germ meal

Authors:

AlmeidaFN, Stein

Publication Type:

Research Reports

Hans H. Stein

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Digestibility of amino acids in corn, corn co-products, and bakery meal fed to growing pigs

Alternative feedstuffs

AA digestibility

Key points