The effect of dietary protein level on the reproductive performance of Mong Cai sows
 

Hoang Nghia Duyet and Nguyen Thi Loc

 Hue University of Agriculture and Forestry, Vietnam

Abstract 

The effects on the reproductive performance of Mong Cai sows of three crude protein (CP) concentrations in gilt, gestation  and lactation  diets were evaluated. Dietary treatments LP, MP and HP consisted of 10, 12 and 14% CP in gilt diets, 8, 10 and 12% CP in gestation diets and 12, 14 and 16% CP in lactation diets, respectively. 

In the gilt rearing period the low (10%) CP diet resulted in significantly higher mean age and lower live weight at first oestrus compared to the medium and high CP diets, which were not significantly different from each other. In gestation the low (8%) CP diet gave significantly lower piglet and total litter live weights at birth than the medium and high CP treatments, although mean litter size was not affected by diet.  The low (12%) CP lactation diet resulted in significantly lower mean piglet and total litter weaning weights, higher sow live weight losses to weaning and longer weaning to oestrus intervals. The differences for all parameters measured between the medium and high CP diets were small and non-significant during the gestation and lactation stages. 

It is concluded that the optimum levels of crude protein for Mong Cai pigs are 12% in gilt rearing diets, 10% in gestation, and 14% in lactation diets.

Key words: Mong Cai sows, reproduction, dietary protein

 
Introduction

Protein plays an important role in sow nutrition and a considerable amount of work has been done on the effect of protein level on the reproductive performance of sows (Dunn and Speer 1988, 1989; Azain et al 1994; Coma et al 1996). Several researchers (Grandhi 1994; Sauber et al 1994; Jones and Stahly 1995) have shown that 10% of crude protein (CP) in the diet gave low body weight gains of gilts. Atinmo et al (1974) fed pregnant sows diets with a CP level of 5%, and observed lower brain weights of the piglets and lower body weights at birth. Mahan et al (1977) showed that 8 to 9 % of CP in the gestation diet caused low litter size at birth and low growth rates of piglets.

Vietnam has about 1 million Mong Cai sows, which is around 50% of the total sow population, and the breed is particularly popular in the North and Central parts of the country, where it is used as parent stock for the production of crossbred fatteners. However, little research has been done on the protein requirements of Mong Cai sows. On the country’s state farms, diets are still based on the recommendations of the Animal Husbandry Institute from 1980 (NIAH 1980). In the rural areas farmers often feed Mong Cai sows with low levels of protein based on locally produced feed resources, such as crop residues and agro-industrial by-products.

Objectives of the research

• To determine the effect of protein level on the growth rate and age at puberty of growing Mong Cai gilts.
•  To determine the optimum dietary protein level for Mong Cai sows in pregnancy and lactation.

Materials and methods

The experiment was divided into three stages (growth, pregnancy and lactation). Three levels of protein (low, medium and high)  were compared which differed slightly according to the stage being studied (see the treatments section  in each Stage).  Details of the dietary ingredients and the amounts offered are in Tables 1 and 2.

Stage 1: Effect of protein level on the growth rate and age at puberty of Mong Cai gilts.

Animals and management

Eighteen Mong Cai gilts were purchased from a breeding area after weaning at 8-10 kg live weight. After 1 week for adaptation and vaccination, they were randomly allocated to 3 treatments (each treatment consisting of 3 gilts, with two replicates per treatment) and given the following diets: 

Dietary treatments

• Low (10% CP) protein (LP)
• Medium (12% CP) protein (MP);
•  High (14% CP) protein (HP).

Measurements

Records were kept of growth rate, feed offered and refused, feed conversion ratio (FCR), age and live weight at first oestrus, age and live weight at first mating.

Stage 2: Effect of protein level in the diet of pregnant Mong Cai sows on reproductive performance

• Animals and management

The animals and their allocation to treatments were the same as in Stage 1. The protein levels in the diets were changed as follows:

• Low (8 % CP) protein (LP)
• Medium (10% CP) protein (MP)
• High (12% CP) protein (HP)

Measurements

Liveweight gain and FCR during pregnancy, and litter size, live weight and mortality of the piglets at birth were measured. 

Stage 3: Effect of protein level in the diet during lactation on the reproductive performance of Mong Cai sows

Animals and management

The animals and their allocation to treatments were the same as in Stage 2. The changeover  to the new protein levels was made immediately after farrowing. The new protein levels were as follows:

• Low (12% CP) protein (LP)
• Medium (14% CP) protein (MP)
• High (16% CP) protein (HP).

 Measurements

Measurements were made of litter size at weaning, liveweight of the piglets at weaning, total liveweight of the piglets at 21 days of age, liveweight loss of the sow during lactation, time interval (days) from weaning to oestrus of sow, number of litters per year and FCR .
 

Results and discussion

The Mong Cai gilts had significantly lower growth rates when fed the low protein diet. Live weight at 8 months of age was 42 kg in treatment LP, 48 kg in treatment MP and 54 kg in treatment HP, which implies mean daily gains of 183 g/day, 217 g/day and 250 g/day, respectively (P <0.01). There were no significant differences between treatments MP and HP. Feed conversion was best in treatment HP and worst in treatment LP (Table 4), as a result of the lower daily live weight gains of the low protein group.

Mean ages at first oestrus and first mating (Table 5) were lower in treatment HP than in treatments MP (P<0.05) and LP (P<0.01).  Mean live weights at first oestrus and mating were also higher in treatment HP than in treatments LP (P<0.01), and in treatment MP compared to LP (P<0.05). The difference between treatments MP and HP was not significant.

Mean piglet birth weights and total litter weight at birth, 21 days and weaning (Tables 6 and 7), were lower for the LP sows than for the MP and HP groups (P<0.05).  There was a tendency for smaller litter sizes at birth and weaning in the LP group, but the differences were not significant.

Mean body weights at mating and after farrowing were lower for the LP group compared with the MP and HP treatments (P<0.05), although net live weight gains in gestation were similar for all treatment groups (P>0.05). Similarly the LP sows lost significantly more live weight during lactation than the MP and HP sows, and this is probably the explanation for their longer weaning to oestrus interval (15.8 days, compared to 4.6 days for the MP sows and 4.0 days for the HP sows).  Although the total feed intake for the whole reproduction cycle was lower for the LP sows, total feed per kg of weaned piglet produced was significantly higher than for the MP and HP groups.

Conclusions

• In the rearing period, diets with medium (12% CP) and high (14%CP) crude protein contents significantly increased gilt growth rates and live weight at first oestrus and mating, and reduced age at puberty.

• Medium (10% CP) and high protein (12% CP) diets in gestation increased piglet birth weights.

• Medium (14% CP) and high (16% CP) protein diets in lactation increased piglet live weights at 3 weeks and weaning, and reduced mortality to weaning.

• The low (12% CP) protein lactation diet resulted in increased sow live weight losses in lactation and increased weaning to service intervals.
   
• The differences between the medium and high crude protein diets for the reproductive parameters measured were not significant. Therefore, the diets containing the medium levels of protein in the rearing (12% CP), gestation (10% CP) and lactation (14% CP) periods are recommended, as they are less expensive than the high protein diets.

References

Atinmo T,   Pond W G and Barnes  R H  1974 Journal Animal Science  39:703

Azian M J, Tomkins T and Sowinski J S 1994  Effect of a protein and energy enriched lactation diet in sow and litter performance: Interaction with supplemental milk replacer. Journal Animal  Science 72 (suppl. 2): 65 (Abstract ).

Coma J, Zimerman D  R   and  Carrion D 1996  Lysine requirement of the lactating sow determined by using plasma urea nitrogen as a rapid response criterion. Journal   Animal  Science  74: 1056 - 1062.

Dunn, J  M and Speer V C 1988  Protein requirement of pregnant gilts. Journal Animal Science 66 (Suppl. 1): 145 (Abstr.)

Dunn, J  M and Speer V C 1989  Minimum nitrogen requirement of pregnant swine. Journal Animal Science 68 (Suppl. 1): 119 (Abstr.)

Grandhi R  R 1994  Apparent absorption and retention of nutrients during the the postweaning period in sows fed supplemental fat or lysine. Journal Animal Science   74: 123-128.

Jones D  B  and Stahly T  S  1995 Impact of amino acid nutrition during lactation on subsequent reproductive function of sows. Journal Animal Science  73 (suppl. 1): 85 (Abstr).  

Mahan D C,  Moxon A L and Hubbard M  1977  Journal Animal Science 45:738

NIAH 1980 Standard nutrient requirements of swine. Animal Husbandry Institute 1980.  Unpublished mimeograph  

Sauber T  E,  Stahly T  S, Ewan R  C  and Williams  N  H 1994 Interactive effects of sow genotype and dietary amino acid intake on lactational performance of sows nursing large litters. Journal Animal Science 72 (Suppl. 2): 66 (Abstr).

Received 6 March 2001

Go to top