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Could Zinc Citrate supplementation during lactation increase the serum Zn levels at weaning?
Zinc is essential for normal growth and development in all animals. In our previous studies it was observed that weaning causes a decrease in the serum Zn, and that piglets with low BW (5.5 kg) at weaning had lower Zn levels (0.79 mg/L) than piglets with a higher BW (8.63kg; 0.98 mg of Zn /L). It was hypothesized that supplementing with 6 mg/d of Zn (19.35mg of Zn Citrate) during the last 10 days of lactation may improve the Zn status at weaning (d 28), especially in light piglets. A total of 48 piglets were selected from 12 litters (2 piglets/litter categorized as heavy 5.7 ± 0.2 kg BW, and 2 piglets as light 3.9 ± 0.3 kg BW) on day 18 of lactation. Experimental treatments consisted on the daily administration of a capsule containing either 0 or 6 mg/d of Zn as Zn Citrate for each piglet and BW category in each sow from d 18 to 28 (12 replicates per treatment and BW category). The 6 mg Zn/d was chosen to be similar to the Zn provided in one kg of sow milk. Body weight was individually recorded on days 18 and 28 of lactation and on days 2, 7 and 14 post-weaning (d 28). Blood samples were obtained on day 18 and 28 of lactation. BW and serum Zn levels were analyzed with ANOVA by using the proc mixed procedure of SAS. All piglets had a drop on the serum levels of Zn, from 0.93 mg/L on day 18 to a 0.74 mg/L on day 28, which may reflect that suckling was likely limiting Zn intake. No different average serum Zn levels were observed according to the BW category for the entire period (0.85 and 0.82 mg/L for heavy and light piglets, respectively; P=0.26), and neither between animals supplemented and non-supplemented at weaning (d 28) (0.76 vs 0.71 mg/L Zn, respectively; P=0.40). However, supplemented piglets had quantitatively higher Zn levels. No different performance was observed due to Zn supplementation for the whole period. In conclusion, supplementing 6 mg/d Zn as Zn citrate for the last 10 d of lactation is not sufficient to prevent the decrease in serum Zn during lactation.
Keywords: Piglets, Zinc Citrate, Zinc Status