Growth performance of weanling pigs fed diets with different inclusion levels of a cheese co-product

Whey, which is a co-product from dairy processing plants that extract fat and protein from milk to make cheese, has been used in diets fed to weanling pigs as a source of lactose. Whey powder does not contain much protein because the majority of the milk protein ends up in the cheese during processing. However, cheese co-products, which contain 40 to 50% crude protein may be used in the feeding of pigs, but there is limited information about the nutritional value of cheese co-products fed to pigs. Therefore, the objective of this research was to test the hypothesis that a cheese co-product may replace traditional protein sources in diets for weanling pigs without affecting growth performance.

Animals, housing, experimental design, and diets

The cheese co-product used in this experiment was sourced from Keys Manufacturing Co., Inc., Paris, IL. Values for standardized ileal digestibility of amino acids and metabolizable energy in the cheese co-product that were determined in previous research were used in formulating diets for this experiment.

A total of 128 newly weaned pigs (initial BW: 6.2 ± 0.6 kg) were allotted to 4 corn-soybean meal-based diets in a randomized complete block design with 4 pigs per pen. A 2-phase feeding program was used with weeks 1 and 2 as phase 1 and weeks 3 and 4 as phase 2. Pigs were fed one of 4 diets during phase 1, whereas all pigs were fed a common diet in phase 2. Thus, a total of 5 diets were used (Table 1). In phase 1, a positive control diet based on corn and soybean meal with 3% spray dried plasma and enzyme treated soybean meal was formulated. Three additional diets were formulated by adding 6, 7, or 14 % of the cheese co-product to the basal diet to replace spray dried plasma, enzyme treated soybean meal, or both spray dried plasma and enzyme treated soybean meal. Individual pig weights were recorded at the beginning and at the conclusion of each phase of the experiment, and daily feed allotments were recorded. At the conclusion of the experiment, data were summarized to calculate average daily gain, average daily feed intake, and average gain:feed ratio within each pen and treatment group.

At the end of phase 1 (day 14), two blood sample were collected from 1 pig in each pen via vena puncture. Serum samples were analyzed for blood urea nitrogen, total protein, and albumin. Plasma samples with EDTA were analyzed for tumor necrosis factor-α (TNF-α), interleukin 6 and 10, immunoglobulin G, and peptide YY.


Results and discussion

All pigs remained healthy during the experiment and easily consumed the provided diets. Results indicated that inclusion of cheese co-product at the expense of protein plasma and/(or) enzyme treated soybean meal in the diets did not affect average daily gain or average daily feed intake (Table 2). However, the gain to feed ratio in phase 1 tended to increase (P = 0.09) as the cheese co-product increased in the diets, which indicates that the ME values for the cheese co-product used in diet formulation may have underestimated the ME of the product. There were no impacts of phase 1 diets on any growth performance parameters in phase 2 when all pigs were fed the same diet.

Blood characteristics were not affected by inclusion of cheese co-products in the diets (Table 3). However, there was a tendency for blood urea nitrogen to decrease linearly (P < 0.10) as cheese co-product increased in the diets indicating that protein was better utilized in diets with increasing levels of the cheese co-product. In contrast, total protein and peptide YY tended to increase (linear, P < 0.10) in blood as cheese co-product increased in the diets. Peptide YY is a hormone that is secreted in response to increased metabolism indicating that the cheese co-product stimulated metabolism in pigs. The concentration of interleukin 10 also tended (quardratically, P < 0.10) to increase as more cheese co-product was included in the diet; because interleukin 10 is an anti-inflammatory cytokine this may indicate a slightly improved immune response and gut barrier function in pigs fed diets containing the cheese co-product.

Key points

  • The cheese co-product used in this experiment had no negative effects on growth performance or blood characteristic of weanling pigs.
  • There were tendencies for increased gain to feed concentration if the cheese co-product was included in the phase 1 diet.
  • There were also tendencies for better nitrogen metabolism, general metabolism, and improved immunity in pigs fed the cheese co-product.


Table 1. Ingredient composition of experimental diets, as-fed basis, phase 1

1 Cheese co-product = sourced from Keys Manufacturing Co., Inc., Paris. IL.

2 HP300 = enzyme-treated soybean meal (Hamlet Protein, Finlay, OH).

3The vitamin-micromineral premix provided the following quantities of vitamins and micro minerals per kg of complete diet: vitamin A as retinyl acetate, 10,622 IU; vitamin D3 as cholecalciferol, 1,660 IU; vitamin E as selenium yeast, 66 IU; vitamin K as menadione nicotinamide bisulfate, 1.40 mg; thiamin as thiamine mononitrate, 1.08 mg; riboflavin, 6.49 mg; pyridoxine as pyridoxine hydrochloride, 0.98 mg; vitamin B12, 0.03 mg; D-pantothenic acid as D-calcium pantothenate, 23.2 mg; niacin, 43.4 mg; folic acid, 1.56 mg; biotin, 0.44 mg; Cu, 20 mg as copper chloride; Fe, 123 mg as iron sulfate; I, 1.24 mg as ethylenediamine dihydriodide; Mn, 59.4 mg as manganese hydroxychloride; Se, 0.27 mg as sodium selenite and selenium yeast; and Zn, 124.7 mg as zinc hydroxychloride.

Table 2. Growth performance of pigs fed diets containing increasing cheese co-product1

1Each least squares mean represents 8 observations for each treatment.


Table 3. Plasma analyses from pigs consuming diets containing increasing levels of cheese co-product1

1Each least squares mean represents 8 observations for each treatment.