Summary

The beneficial effects of the use of the vitamin D3 metabolite, the 25-hydroxyvitamin D3 (25-OH D3), are more and more recognized on the skeleton development in the poultry feed industry. The purpose of this study run with turkeys during 15 weeks was to confirm this effect. It evaluated the incidence of 25-OH D3 (commercial name Hy-D®) for two vitamins levels (control or OVN^TM reinforced in 13 vitamins) with meat turkey BUT 9. Four vitamin premixtures (control, control + Hy-D, OVN and OVN + Hy-D) were tested. The introduction of Hy-D was carried out in partial substitution to the vitamin D3 of the corresponding control.

The reinforcement of the vitamin supply, with OVN levels, shows, in a context of under-consumption in starter period, a good start of the growth turkeys thanks to a better intake. The benefit of this effect is observed up to 12 weeks. Beyond 12 weeks, the use of Hy-D prove to be necessary to prolong this asset on the growth and to minimize the frequency of the lameness disorders at the end of the breeding.

Whatever the vitamin supply, the use of Hy-D in the turkey feed allows, to improve the weight and percentage of fillets (+0,8 point) and to reduce to a significant degree the frequency of the lameness disorders (+20 points of optimal note) and to increase the bone resistance to the fracture; a slightly higher growth is observed constantly.

Introduction

The locomotive problems that the heavy turkey suffers from in the final stage of turkey raising are a real problem for poultry farmers today. To remedy this situation, a substantial dose of vitamin D3 (cholecalciferol) appears indispensable. This vitamin does not however act directly on the metabolic system of the bird. It is first of all converted in the liver through an endogenous process of synthesis into 25-hydroxy vitamin D3 (25-OH D3), which in its turn is hydroxylized in the kidney. Among the substances resulting are 1.25-dihydroxy vitamin D3, the principal metabolite for the regulation of calcium and phosphorus levels. Under intensive farming conditions the sanitary state of the birds is not always ideal, and this means that their ability to absorb these nutrients deteriorates. A dose of 25-OH D3 facilitates more rapid absorption and enhances the availability of the nutrients.

Recent studies summarized by Applegate and Angel (2004) demonstrate that the metabolites of vitamin D3 have an effect on the skeletal development and laying frequency of poultry. Vitamin 25-OH D3 improves the bird’s utilization of phosphorus, and a positive interaction with the phytases also takes place. Positive effects on the immune system have likewise been confirmed by a number of authors.

In practice Hy-D (the commercial name for the vitamin 25-OH D3 produced by DSM Nutritional Products) is recommended for all the physiological stages involved in turkey hen farming:

• For layers, with the aim of enhancing the quality of the shell and improving stores of this metabolite in the embryo,
• Between hatching and the age of 10 days, to diminish the impact of rickets at an early stage of poultry raising,
• In the startup phase (7 to 21 days), to help the bird in this critical period of scanty nutrition and inadequate absorption, resulting in a deficiency of calcium, phosphorus and vitamin D3,
• Between 8 and 12 weeks in the United States, as a remedy for enteritis problems,
• After this the dose is maintained at a lower level for its prophylactic effect in averting problems of tibial dyschondroplasia, and to improve the performance of the turkey cock (live weight and percentage of fillet meat).

In Europe DSM currently recommends a 62.5 µg/kg dose of Hy-D in the first 6 weeks, and 50 µg/kg after that. In its ongoing endeavor to find the ideal balance between vitamin D3 and 25-OH D3, the DSM company commissioned ADÆSO to carry out a study with a higher dose (80-90µg/kg) of Hy-D® in the first six weeks, followed by a reduced dose (40-50µg/kg) through to the end of the raising process. The presence of Hy-D is evaluated for two different vitamin doses, a control substance and OVN™ (Optimum Vitamin Nutrition) as recommended by DSM (2004).

1. Materials and Methods

Four experimental treatments were assessed over a period of 15 weeks, using the meat turkey cock as a subject, at the ADAESO poultry centre in Montardon (64) from March to June 2004.

Table 1. Plan of experiment
Treatment	1	2	3	4
Premix of vitamins	Control substance		OVN
Hy-D	0	+	0	+

TABLE 1 – Feed and premix characteristics
Period	Starter (0-3 wks)				Growth 1 (4-6 wks)				Growth 2 (7-12 wks)				Finisher (13-15wks)
Prx Vitamins	Control		OVN		Control		OVN		Control		OVN		Control		OVN
Hy-D	-	+	-	+	-	+	-	+	-	+	-	+	-	+	-	+
Theoritical contents, mg/kg feed (except IU)
Vit.A, IU	11800		13500		11800		13000		11400		11000		8850		10000
D3, IU	4250	1100	5000	1300	4250	1100	5000	1300	3700	1850	4000	2000	2700	1160	3500	1500
Hy-D, IU	-	3150	-	3700	-	3150	-	3700	-	1850	-	2000	-	1540	-	2000
E	30		250		30		60		25		50		20		40
K3	2.86		4.00		2.86		4.00		2.54		4.00		1.93		4.00
B1	2.10		5.00		2.10		5.00		1.90		3.00		1.40		3.00
B2	6.80		20.00		6.80		15.00		6.10		7.00		5.00		7.00
B6	4.10		7.00		4.10		7.00		3.70		6.00		2.90		6.00
B12	0.02		0.04		0.02		0.04		0.019		0.03		0.013		0.03
Niacin	64		150		64		100		61		80		49		70
Pantoth. Acid	13		25		13		20		12		15		11		15
Folic Acid	1.23		4.00		1.23		3.00		1.18		2.00		0.90		2.00
Biotin	0.19		0.50		0.19		0.25		0.14		0.02		0.12		0.20
C	0		200		0		200		0		200		0		200
Cholin	550		1100		550		750		525		500		385		500
Analytical contents, kg feed
D3 (*), UI	3200	720	3600	1300	1700	500	2000	1100	2550	1550	3100	1950	1900	1100	2700	1300
Hy-D, UI	-	3348	-	2988	-	1548	-	1348	-	1600	-	1350	-	1260	-	1972
Calcium, %	1.30	1.35	1.22	1.33	1.34	1.41	1.30	1.49	1.16	1.45	1.32	1.39	1.15	1.08	1.14	1.20
Phosphorus, %	1.09	1.02	1.04	1.07	0.93	0.94	0.94	0.97	0.84	0.87	0.88	0.84	0.81	0.79	0.83	0.82
(*) Equivalence: 1 mg of D3 or 25-OH-D3 have the same vitminic activity : 40 International Units (UI).

1.1 Nutrients supplied in the course of the experiment

The four diets used for the experiment are identical in their centesimal composition but different in terms of the vitamin profile involved (see Table 1):

• Treatment 1 consists of the control substance nutrient, supplemented with a dose of classic vitamins,
• Treatment 2 is equivalent to that using control substance but with a partial substitution of 25-OH D3 (Hy-D) for vitamin D3,
• Treatment 3 has an enhanced dose of 13 vitamins by comparison with the control substance (T1) (cf. OVN; recommendations),
• Treatment 4 is equivalent to treatment 3, with a partial substitution of 25-OH D3 for vitamin D3.

These four diets were distributed ad libitum to 648 turkey cocks of the stock BUT 9, divided at the age of 1 day between the 24 raising grounds of the experimental centre in a ratio of 6.75 birds to the square metre up to 9 weeks of age, and 4 to the square metre thereafter.

1.2 Measurements carried out in the course of raising

The birds are weighed individually at the age of 3, 6, 9, 12 and 15 weeks. They are given as much water and food as they require. The amount they consume is measured for each week, the indices of consumption being calculated for each raising ground (6 for each treatment). The index of performance (IP) is calculated for each raising ground at the end of the experiment, according to the formula IP = [GMQ(g/j) x viability at 15 weeks x 10]/IC. The birds being raised are observed, and notes taken on a daily basis. At 12 to 15 weeks, 48 turkey cocks undergoing the experimental treatment are subjected to a locomotive test (using the method developed by Kestin et al., 1992). The classification scale comprises six categories, from the ideal category 0 (normal mobility) to category 5 (unable to move at all). At the end of the test, 24 representative turkey cocks taken from the experimental group are subjected to tests on the right tibia developed by the ROSLIN Institute (UK), to assess resistance to fracture.

1.4 Statistical treatment

The weight variables are treated by analyzing variations between the four treatments (GLM procedure, SAS 8.2). The qualitative variables form the object of a KHI² test.

2. Results

The results of analysis of the different diets (Table 1) confirm the hierarchy of control substance to OVN. With reference to the D3 or Hy-D, the analysis is delicate, and rates of recovery are on the whole acceptable. The diets of growth phase 1 however demonstrate lower levels, whatever the treatment, but the dose is still superior to requirements.

2.1 Zoological performance

In a startup situation that is difficult on account of an observed nutritional deficiency (-16% in relation to reference figures for the stock in question), problems of locomotion – diagnosed as chondrodystrophy with a fragile bone structure – become apparent at the age of three weeks. This pathological situation entailed the elimination of several subjects at the age of 9 weeks. This confirms that the frequency of elimination is reduced in the presence of Hy-D; and of OVN on its own (2.5 for T2 and T4 and 3.7% for T3, as against 7.4% for the control substance group T1).

In these conditions, at the age of 3 weeks the presence of OVN on its own (T3) results in a significantly superior ability to absorb nourishment – 6.2% better by comparison with the vitamin level of the control substance group, with or without Hy-D supplement (775 vs 730 g on average for T2 and T1 respectively). The treatment with OVN + Hy-D together (T4) falls between the two (755 g). Live weight at 3 weeks tends to follow the same pattern, with a difference of 4.7% between T2 and T1 (531 as against 507 g on average respectively), and treatment 4 coming between the two at 522 g. The indices of consumption are not significantly different.

At the age of 6 weeks these effects fade out, but the index of consumption shows an improving tendency (-3.0%; p = 0.10) with treatment 4 by comparison with treatments 1 and 3 (1.63 vs 1.68) when not supplemented with Hy-D. Treatment 2 yields an intermediate result (1.65). At 12 weeks, for the similar levels of consumption observed between treatments, the growth of the birds of the treatment 3 group again appears to be significantly superior (+3.7%) to that of the birds of the treatment 1 group (8653 vs 8343 g). For treatments 2 and 4, supplemented by Hy-D, growth is intermediate (8538 g on average). The indices of consumption show a tendency to improvement with a factor of 2.5% (p = 0.15) with treatments 2, 3 and 4 by comparison with T1 (1.99 on average vs 2.04).

In the last period of raising this effect on growth fades out. At 15 weeks, the difference between T3 and T1 is only 0.8% in favor of treatment 3 (11541 vs 11451 g respectively). The birds of the treatment 1 group have made up for their retarded development in the last stage. In the final phase the index of consumption tends to reach the highest level (p = 0.12; 2.34), while the live weight is slightly lower by comparison with the other treatments. Treatment 2 again yields intermediate results (11541 g and 2.32). The birds given treatment 4 (OVN + Hy-D) had the best growth and the best index of consumption in the final phase of raising. This results in the best performance overall at 15 weeks. The live weight is slightly higher (but not in a statistically significant sense), by a factor of 2.5% (11740 vs 11451 g), while the index of consumption shows an improving tendency, with a factor of 3.4% by comparison with the control substance group T1 (2.26 vs 2.34).

The index of performance (IP) underlines the significantly marked effect of Hy-D in the case of the nutrient OVN (466 vs 417, 408 and 424 for T1, T2 and T3 respectively).

TABLE 2 – Zootechnical performances
Treatments	1	2	3	4
Premix vitamins	Control		OVN
Hy-D	0	+	0	+	Average	SD	Proba. sous H0 (1) Treatment effect
Elimination at 9 wks.,%	7.4	2.5	3.7	2.5	4.0	-	-
Intake 3 weeks, g	738 b	721 b	775 a	755 ab	747	21	**
Weight 3 weeks, g	504	509	531	522	517	17	0.08
FC 3 weeks, kg/kg	1.46	1.42	1.46	1.44	1.45	0.05	NS
Intake 6 weeks, g	3258	3201	3336	3238	3258	97	NS
Weight 6 weeks, g	1953	1944	1991	1982	1968	57	NS
FC 6 weeks, kg/kg	1.67	1.65	1.68	1.63	1.66	0.03	0.10
Intake 12 weeks, g	17006	17115	17180	16926	17067	449	NS
Weight 12 weeks, g	8343 b	8568 b	8653 a	8508 ab	8518	152	*
FC 12 weeks, kg/kg	2.04	2.00	1.99	1.99	2.00	0.04	0.15
Intake 15 weeks, g	26843	26763	26344	26533	26622	657	NS
Weight 15 weeks, g	11451	11541	11541	11740	11568	236	NS
FC 15 weeks, kg/kg	2.34	2.32	2.28	2.26	2.30	0.05	0.12
Index of performance	417 b	408 b	424 b	466 a	429	24	**
(1) *, ** : significant effect with P<0.05, 0.01 ; NS : P> 0.15. a-b différence significative entre groupes pour un paramètre avec P<0.05, 0.01.

2.2 Locomotive difficulties and bone resistance to fracture

At 12 weeks, the frequency of locomotive difficulties is no different between the treatments. At 15 weeks, where Hy-D is administered this criterion is significantly reduced (+20 points of top marks A: 80.4% and 84.8% for T2 and T4. as against 60.4% and 64.6% for T1 and T3). The tibias tend to show more resistance to fracture (p = 0.15; 733 and 701 N for T2 and T4 vs 695 and 647 for T1 and T3). With OVN, the bones have a tendency to be less resistant, with reduced variability.

TABLE 3 – Locomotive difficulties (LD) and maximum load resulting in fracture (MLF)
Treatment	1	2	3	4	Effect of Treatment
Premix of vitamins	Control substance		OVN
Hy-D	0	+	0	+	(1)
LD top marks A, %
12 Weeks	72.3	81.3	74.5	80.9	Π² = NS
15 Weeks	60.4	80.4	64.6	84.8	Π² = **
MLF (15 weeks), N	695 ±141	733 ±157	647 ±106	701 ±103	P=0.15
(1) cf. Table 2.

2.3 Corporeal constitution

There are no significant differences between treatments as regards the deposit of abdominal fat. The mass of the fillet meat produced is not significantly different between treatments, though treatment 4 makes it possible to achieve the highest level (2445 g) with the least degree of variability (242 vs 279, 295 and 278g for T1, T2 and T3 respectively), while treatment T1 results in the lowest level (2256 g) – yielding a difference of 8.3%. The addition of Hy-D to each premix of vitamins tends to improve the yield of the fillets (p = 0.08; +0.8 or 23.2 vs 22.4% on average). As for the weight of the thighs/drumsticks, there is no significant effect between treatments. As with the mass of the fillet meat, it is slightly higher with treatment 4 (2955 g) and lower with treatment 1 (2840 g) – a difference of 4.0%.

TABLE 4 – Corporeal constitution
Treatments	1	2	3	4
Premix vitamins	Témoin		OVN
Hy-D	0	+	0	+	Average	SD	Proba. sous H0 (1) Treatment effect
Abdominal fat, g	125	102	122	151	125	65	NS
Fillets, g	2256	2388	2349	2445	2360	274	NS
Fillets, % dry weight	22.2	23.2	22.6	23.2	22.8	1.3	0.08
Thighs, g	2840	2937	2898	2955	2908	294	NS
(1) cf tableau 2.

Conclusion and Discussion

This study evaluates the impact of the introduction of 25-OH D3 (commercial name Hy-D) as a partial substitute for vitamin D3 in two levels of vitamin dosage (control substance or OVNTM with an enhanced dose of 13 vitamins). The effects on the zoological performance, bone development and corporeal constitution of turkey cocks of stock BUT 9 raised over 15 weeks were observed. In the conditions of this experiment, the zoological results suggest that birds receiving an enhanced vitamin dose (OVN), and in particular the birds of the treatment 3 group (OVN without Hy-D), have a better start to growth. This result probably favored the performance of the birds up to the age of 12 weeks (live weight higher, improved index of consumption). After this point the appearance of serious locomotive difficulties put a brake on growth, but the increase in the index of consumption was maintained. On the other hand, the muscular development (weight and yield of fillet meat) was less than ideal. The birds given treatment 4 had a good start (slightly below that of treatment 3). At 12 weeks, the index of consumption is identical with that of treatment 3, with a slightly lower live weight. Beyond the twelve week point, the dosage of Hy-D makes it possible to prolong the effect of increased growth and improved efficiency in processing nourishment, while avoiding the development of locomotive difficulties. Thus the effect on muscular development is favorable. The birds given treatment 2, involving Hy-D, in spite of a startup performance that was inferior to those of treatments 3 and 4, nonetheless catch up with the performance of treatment 3 at the age of 15 weeks, along with superior muscular development and a reduced frequency of locomotive difficulties. The birds given treatment 1 show significantly retarded growth at 12 weeks (a difference of 310 g by comparison with the T3 group). In the last period of raising, these birds had the highest level of growth, at the cost of a poor index of consumption and a greater frequency of locomotive difficulties. The good result as far as growth is concerned does nothing for the muscular development.

The use of Hy-D in the diet of the heavy turkey makes it possible, whatever the vitamin dose, to achieve slightly improved performance as regards growth, but above all gives enhanced weight and fillet yield, as Weber reports (2004). It also makes it possible to reduce the frequency of locomotive difficulties to a significant degree. This result may be compared with those observed by Rennie and Whitehead (1996) in chickens. It may be related to an improvement in the bird’s ability to absorb the nutrients calcium, phosphorus and vitamin D3, as reported by Weber (2004).

The enhanced dosage of vitamins (OVN) has a beneficial effect on the absorption of nourishment, and thus on the bird’s growth in the startup phase. This fact, already observed in chickens by Castaing et al. (2003), is all the more interesting in connection with the raising of turkey hens, as for these birds this period of insufficient nourishment remains problematic. It appears that the enhanced vitamin dose should be coupled with a dose of 25-OH D3 in order to preserve the beneficial effect, in view of the birds’ final performance in terms of growth, bone development and corporeal constitution.

Research on the subject of 25-OH D3 and vitamin levels are far from complete. We need to know more about the periods involved and duration of use, as well as the dosage that is ideal in the life of the turkey.

References

Applegate Todd J. et Angel Roselina, 2004. In: 62nd Minnesota Nutrition Conference and Minnesota Corn Growers Association Technical Symposium, Bloomington MN, USA, 11-12/09/2001 : 9 pp
Castaing J., Larroudé P., Peyhorgue A., Hamelin C. et Maaroufi C., 2003. 5èmes Journées de la Recherche Avicole, Tours, 26-27 mars 261-264.
DSM Vitamin Supplementation Guidelines for domestic animals, 2004. DSM édit., Kaiseraugst Suisse 10pp
Kestin SC, Knowles TG, Tinch AE, Gregory NG., 1992. Vet . Rec. ,;131(9): 190-194.
Rennie J.S. and Whitehead C.C., 1996. Poult.Sci. 37:413-421.
SYSAAF - INRA, décembre 1995. La découpe anatomique et la dissection des volailles, le poulet, le canard, la dinde.
Weber Gilbert M., 2004. 5th International Symposium on Turkeys Diseases, Berlin.

March 2010