Zinc repletion with organic or inorganic forms of zinc and protein turnover in marginally zinc-deficient calves.
We conducted two experiments using marginally Zn-deficient (-Zn) calves to determine which supplemental chemical form of Zn would most rapidly reverse certain Zn deficiency signs and to determine whether a change in protein turnover had occurred in Zn deficiency. In Exp. 1, 40 crossbred beef heifers were allocated by BW to four groups. The control group received 23 mg Zn/kg diet DM from ZnSO4 supplemented to the -Zn diet (17 mg Zn/kg diet DM). The three other groups received the -Zn diet. After 21 d, based on a decreased (P < .05) feed efficiency, they were deemed -Zn. Cell-mediated immune (CMI) response to phytohemagglutinin (PHA) was reduced (P < .05) but plasma and liver Zn were unaffected in the -Zn calves. Zinc was repleted by feeding iso-Zn amounts (23 mg Zn/kg diet DM) from Zn lysine, Zn methionine, or ZnSO4. At 8 h after injection of PHA, control CMI response values were similar to Zn Methionine, and Zn lysine was lower (P < .05). In Exp. 2, 10 Holstein steers were allocated by BW to two groups. One group received the -Zn diet, and the other received the +Zn diet. Urine collections were obtained from both groups of calves when the -Zn calves showed a decrease (P < .05) in feed efficiency relative to the controls and when they were repleted with 23 mg Zn/kg diet DM from ZnSO4 and their feed efficiency had returned to that of the controls. Urinary 3-methylhistidine indicated that -Zn calves had less (P < .05) daily protein degradation than the controls. Refeeding Zn to the -Zn group did not change BW or daily protein degradation. Results indicated that a marginal Zn deficiency decreased fractional accretion rate, increased (P < .05) urine excretion, and tended to increase (P < .19) Na and decrease (P < .12) K concentrations in the urine.
Engle
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TE
Department of Animal Sciences, Colorado State University, Fort Collins 80523, USA.
Nockels
C F
CF
Kimberling
C V
CV
Weaber
D L
DL
Johnson
A B
AB
D000818:Animals; D001724:Birth Weight / Q000502:physiology; D002417:Cattle / Q000097:blood / Q000254:growth & development / Q000378:metabolism*; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements; D005260:Female; D008099:Liver / Q000737:chemistry; D008297:Male; D008762:Methylhistidines / Q000652:urine; D010835:Phytohemagglutinins / Q000494:pharmacology; D011188:Potassium / Q000652:urine; D011506:Proteins / Q000378:metabolism*; D012867:Skin / Q000187:drug effects; D012964:Sodium / Q000652:urine; D013997:Time Factors; D015032:Zinc / Q000032:analysis / Q000172:deficiency* / Q000494:pharmacology*
D008762:Methylhistidines; D010835:Phytohemagglutinins; D011506:Proteins; D012964:Sodium; D015032:Zinc; C028118:3-methylhistidine; D011188:Potassium