147 Dietary Zinc and its Effect on Collection Time and Training Quality of Young Boars for Obtaining Ejaculates

Abstract

It is known that Zinc (Zn) is important in several aspects of reproduction, including fertility and the production of sexual hormones. The aim of the present study was to evaluate different amounts and types of Zn on ejaculate collection time and training behaviour of young boars. For this purpose, non-castrated domestic boars (York × Landrace, Sus scrofa domesticus), with an average age of 6.8 months and initial weight of 120 kg (body condition score of 3), were assigned to 3 different groups (5 per group). The base diet consisted of cereal-soybean feed, complemented with a mixture of minerals and vitamins without the addition of extra Zn. The Zn concentration was determined using atomic absorption photospectrometry, specifically, with a Varian SpectrAA 220 Atomic Absorption Spectrometer (Varian, Palo Alto, CA, USA) and following manufacturer instructions. The effect of Zn was evaluated by administering the young boars different amounts and sources of the mineral: (1) Control = 25 ppm of Zn, (2) T1 = Control + 125 ppm ZnSO₄ (inorganic), and (3) T2 = Control + 125 ppm Zn-methionate (Zn-Met, organic). The boars were given an adaptation period of 15 days to acclimate to the feed, and afterwards they underwent the training process for ejaculate collection for 4 more weeks. Boars were collected an average of 2.95, 2.67, and 2.69 times for Control, T1, and T2. Several variables were used in order to determine the existence of treatment effects, including number of training sessions (NTS); interval between training (days, IBT); false mounts (mounting dummy but dismounting before allowing semen collection, FM); effective mounts (duration of mounting dummy and completion of semen collection, EM); and duration of ejaculation (min, DE). The results were analysed with PROC MIXED using the statistical package SAS (SAS Institute Inc., Cary, NC, USA), with statistical differences set at α < 0.05. Even though significant differences were not observed between most of the variables analysed (e.g. NTS, FM, EM, DE), differences did exist between treatments for the variable IBT (P = 0.013). Notably, although there was no significant difference between treatments for the variable DE, it was higher for T3 (6.49 min, P = 0.54) than for T1 and T2 (5.87 and 5.27 min, respectively). In conclusion, the addition of 150 ppm of organic Zn (i.e. Zn-Met) significantly reduced the time interval for training the boars, which may be due to a better libido, and demonstrated the importance of considering types and dose amounts of dietary Zn and its effects on reproduction.