Carnitine Supplemented Finishing Pig Diet

FIG. 1 is a graph of the effect of carnitine intake on backfat of barrows and gilts, backfat (cm) versus carnitine intake (mg/kg body weight/day).

FIG. 2 is graph of the effect of carnitine intake on weight gain of barrows and gilts, daily gain (kg) versus carnitine intake (mg/kg body weight/day) .

Increased weight gain and feed efficiency can be achieved by supplementation of animal feeds containing minimum required levels of lysine with L-carnitine. The amount of required lysine and effective amount of L-carnitine is dependent on the age, sex, species, breed, and feed composition. Growth rate, feed conversion, and carcass composition are affected not only by nutrient intake, but also by breed, strain, sex and age. The criteria selected as indicative of a response to a particular diet or ingredient can influence requirements. For example, maximal carcass leanness may require greater concentrations of certain nutrients than maximal rate of gain. Lean pigs deposit more protein in their gain, which increases their requirements for protein and individual amino acids. Leanness is associated positively with feed efficiency; requirements for maximal feed efficiency are generally greater than those for maximal weight gain.

"Nutrient Requirements of Swine", Nutrient Requirements of Domestic Animals Number 2, eighth revised edition (National Academy of Science, Washington, D.C. 1979), provides extensive guidance in formulating diets for the feeding of swine. In the United States, most pigs are fed a diet consisting of approximately 97% corn and soybean with the remaining 3% consisting of carriers combined with one or more inorganic elements, vitamins, or antimicrobial compounds. For example, a standard diet may contain 79.5% corn; 17.4% soybean meal; 0.9% defluorinated phosphate; 0.65% limestone (35% Ca); 0.25% sodium chloride; 0.25% vitamin premix; 0.25% trace element premix; and 0.25% antimicrobial premix. Oats, sorghum and synthetic amino acids are sometimes added. In Europe, corn and soybean meal are generally not as available nor as cost effective as beans, peas, barley, wheat, rape seed meal, cassava (tapioca), molasses, fish, bone and meat meal. These materials do not yield as fast of a growth rate as soybean meal and corn.

In the United States, most swine producers wean piglets at approximately 21 to 28 days of age, at weights for crossbred piglets of about 10 pounds (4.8 to 5.2 kg) to 15 pounds (6.5 top 7 kg). Pigs between about two up to about three to four months of age, weighing between about 40 pounds (18 kg) and 110 pounds (50 kg), which are able to be maintained in non-temperature controlled environments, are called growing pigs. Finishing, or feeder, pigs are pigs being readied for market and range in weight and age from approximately greater than 110 pounds (50 kg) u to 220 pounds (100 kg) to 230 pounds (104 kg) and from greater than about four months up to approximately five to six months.

The dietary requirements for finishing pigs are quite different from nursery and growing pigs. Tables 5 and 6 of the Nutrient Requirements of Swine lists the amino acids, mineral elements, vitamins, and other dietary requirements for swine as a function of weight. For example, the lysine requirement for nursery pigs is from about 3.2 to 4.8 g daily, or from 1.25 to 0.95% of diet. The lysine requirement for finishing pigs ranges from approximately 12.2 to 17.1 g daily, or 0.61 to 0.57% of diet.

Carnitine is not listed as part of the daily nutritional requirements for swine. It was determined in the studies reported in 1986 and 1987 that the optimum amount of carnitine added to a diet for nursery pigs which was adequate in lysine was about 2000 ppm for a mixture of D- and L-carnitine, and about 800 ppm of L-carnitine. It has now been determined that diets containing from approximately 0.1 to 400 ppm, most preferably between 5 and 50 ppm, L-carnitine produce a significant increase in weight gain and feed efficiency in finishing pigs receiving a diet containing greater than 0.6% lysine, preferably about 0.7 to 0.8% lysine, an increase in the normal dietary amounts. Supplements may also be provided to the animals' normal diet to provide between 0.1 to 15 mg L-carnitine/kg body weight/daily, preferably between 0.1 and 2.0% L-carnitine. The amount of carnitine producing this effect is drastically less than the amount producing an effect in nursery pigs, even though the amount of lysine is decreased by a factor of less than one third.

The effect is sex dependent. As shown in the accompanying figures, described in more detail below, a much more dramatic effect of the carnitine administration is noted in gilts than in barrows. Gilts are leaner animals and therefore have a higher metabolic rate. The L-carnitine may therefore play a greater role in utilization of fatty acids for energy in gilts than in barrows.

The method for increasing feed efficiency and weight gain consists of providing lysine and L-carnitine levels in a feed composition to produce the maximum effect as a function of age and sex of the pigs. These amounts can be optimized for individual feed compositions or pig breeds by conducting studies of the nature described in the following examples. It is possible to optimize the diet to favorably alter the levels of fat in the tissue, based on these studies.

The effect of the combination of lysine and L-carnitine can also be optimized by adding additional sources of methyl groups for utilization in the conversion by the animal of lysine to carnitine. Examples of methyl donors known to those skilled in the art include methionine and choline. Choline would be administered at between 200 and 800 mg choline/kg.

The L-carnitine diets and supplements, and methods for utilization thereof, can be applied to other feeder animals such as feedlot cattle. Cattle are put into feedlots for between 90 and 120 days, usually 112 days, either shortly after weaning (at a weight of approximately 400 to 500 pounds) or more typically, after a second summer on grass (at a weight of between 700 and 900 pounds). The latter group are considered analogous to finishing pigs.

The present invention will be further understood with reference to the following non-limiting examples.

Forty-two finishing pigs, 21 barrows and 21 gilts, average weight 74.6 kg, were provided with corn-soy diets containing 0.6% lysine and either 0, 5 or 10 ppm added L-carnitine. The pigs were individually housed and fed, and were removed from test after 35 days. The average weight of the pigs was 106.7 kg. The diet for the finishing pigs fed supplemental L-carnitine consisted of:

During the first 14 days pigs fed 5 ppm carnitine consumed less (p<0.05) feed than pigs fed the control diet (3.01 vs 3.33 kg/pig/day), but there were no significant differences for weight gain or feed efficiency. During the second 14-day period there was an interaction (p<0.05) between dietary carnitine and sex of pig for feed intake. Barrows fed the 10 ppm diet consumed more feed than barrows on other diets (3.96, 3.41 and 3.42 kg/pig/day for 10 ppm, 5 ppm and control diets, respectively) while gilts consumed slightly less (2.94, 3.11 and 3.14 kg/pig/day for 10 ppm, 5 ppm and control diets, respectively). Over the trial, there were differences in gain (0.83, 0.86 and 0.84 kg/day for pigs on a control diet or receiving 5 ppm and 10 ppm L-carnitine, respectively), feed intake (3.38, 3.30 and 3.35 kg/day for control, 5 ppm and 10 ppm L-carnitine, respectively), feed/gain (4.11, 3.92 and 4.04 for control, 5 ppm and 10 ppm L-carnitine, respectively) and backfat (2.73, 2.69 and 2.76 for control, 5 ppm and 10 ppm L-carnitine, respectively) due to carnitine supplementation. In general, pigs fed L-carnitine consumed less feed and grew more slowly near the beginning of the trial and grew faster on the same amount of feed during the last 14 days of the trial, compared to pigs fed the control diet.

A second group of forty-two finishing pigs, 21 barrows and 21 gilts, average weight 75.9 kg, were provided with corn-soy diets containing 0.6% lysine and either 0, 5 or 10 ppm added L-carnitine. The pigs were individually housed and fed, and were removed from test after 28 days. The average weight of the pigs was 102.5 kg. The diet was as described in example 1.

The initial weights for the three groups were initially the same. Over the first fourteen days, the daily gain, in kg, was 1.04, 0.89, and 0.98 for 0, 5, and 10 ppm L-carnitine, respectively. The daily feed, in kg, was 3.53, 3.27, and 3.59 for 0, 5, and 10 ppm L-carnitine, respectively. The gain/feed ratio was 0.29, 0.25, and 0.27 for 0, 5, and 10 ppm L-carnitine, respectively.

Performance was then compared after an additional fourteen days (total of 28 days). The final weight for the three groups was 102.5, 102.1, and 101.8, for 0, 5 and 10 ppm L-carnitine, respectively. Daily gain for the second fourteen days, in kg, was 0.91, 0.96, and 0.91 for 0, 5, and 10 ppm L-carnitine, respectively. Daily gain for the entire 28 days, in kg, was 0.97, 0.93, and 0.95 for 0, 5, and 10 ppm L-carnitine, respectively. Daily feed for the second fourteen days, in kg, was 3.28, 3.36, and 3.57 for 0, 5, and 10 ppm L-carnitine, respectively. Daily feed for the entire 28 days, in kg, was 3.36, 3.22, and 3.42, for 0, 5, and 10 ppm L-carnitine, respectively. Gain/feed ratio for the second fourteen days was 0.28, 0.28 and 0.27 for 0, 5, and 10 ppm L-carnitine, respectively. Gain/feed ratio for the entire 28 days was 0.27, 0.27, and 0.26, for 0, 5, and 10 ppm L-carnitine, respectively. The backfat levels, in cm, for the entire 28 days, was 2.71, 2.64, and 2.99 for 0, 5, and 10 ppm L-carnitine, respectively. These differences are statistically significant at p<0.05.

When data from the two trials was combined, the initial observations were reinforced. Over the first fourteen days, the daily gain, in kg, was 0.92, 0.80, and 0.87 for pigs fed 0, 5, and 10 ppm L-carnitine, respectively. The daily feed, in kg, was 3.43, 3.14, and 3.33. These differences are statistically significant at p <0.05. The gain/feed ratio was 0.27, 0.24, and 0.26 for pigs fed 0, 5 and 10 ppm L-carnitine, respectively.

When the effect of dietary carnitine on feed consumption over the first fourteen days was analyzed on the basis of sex, the differences were statistically significant at p <0.10. Daily feed, in kg, was 3.51, 3.33, and 3.47 for barrows, and 3.36, 2.94, and 3.17 for gilts, for 0, 5, and 10 ppm L-carnitine, respectively.

The effect of pig sex and dietary carnitine on feed consumption after 28 days was as follows. Daily feed, in kg, for barrows fed 0, 5, and 10 ppm L-carnitine, was 3.44, 3.42, and 3.67, respectively. Daily feed, in kg, for gilts fed 0, 5 and 10 ppm L-carnitine, was 3.27, 3.02, and 3.12, respectively. The effect by sex of the different levels of carnitine on backfat is shown in FIG. 1. The effect by sex of the different levels of L-carnitine on daily gain is shown in FIG. 2. Gilts exhibit a pronounced curvilinear response in both backfat and daily gain in response to supplementary L-carnitine. It is therefore possible, by varying the levels of L-carnitine administered to pigs of different ages and sexes to alter the amount of fat in the tissue.

Modifications and variations of the present invention, feed compositions and methods for formulation and administration thereof to finishing pigs, will be obvious to those skilled in the art from the foregoing detailed description. Such modifications and variations are intended to come within the scope of the amended claims.