Strategic feeding supplementation: An alternative for sustainability of beef production in native pastures

The present study aimed to evaluate the effects of a strategic feeding supplementation protocol on reproductive and economic results of exclusively fixed timed artificial inseminated (FTAI) beef cows from a southern Brazilian herd. The experiment was carried out over 2 consecutive breeding seasons (2016 and 2017, from October to January). Two-hundred, 3 and 4 years old, non-suckled, Angus cows (n=100/year), were divided into two homogeneous groups (by weight and body condition score) 25 days before the first FTAI of the breeding season (First FTAI=Day 0). As a representation of traditional management of herds grazing on natural pastures from Rio Grande do Sul Province, Brazil, cows from control group (CG; n=100; 50 cows in each year) received basic mineral supplementation (without protein an energy) ad libitum during the entire experimental period. As an alternative feeding protocol, supplemented group (SG; n=100; 50 in each year) received a mineral supplementation enriched with protein (23%), energy (44% NDT) and sodium monensin (0.25%) ad libitum from days: –25 to 80 of breeding season. Cows were maintained in 2 separated paddocks of native pasture with similar forage composition and availability. All cows were submitted to a progesterone/estradiol-based estrus synchronization protocol on day -10, and cows not pregnant at diagnosis were resynchronized on days 28 and 76 using the same hormonal treatment. There was no year effect (P>0.1) on weight gain and reproductive results, data from both breeding seasons were polled together for further analyzes. Cows from SG presented higher average daily weight gain and gained more weight than cows from CG (p<0.001). Conception rate was higher for SG than CG at the first FTAI cycle (p<0.05). No differences between groups were detected on final pregnancy rates (CG=80% and SG=88%; p>0.1). Cows from SG became pregnant earlier (p<0.01) during the breeding seasons. Also, the feeding supplementation provided an opportunity to increase gross margin. In conclusion, strategic feeding supplementation of beef cows grazing in natural pasture and submitted exclusively to fixed timed artificial insemination increases cows’ weight gain, anticipates pregnancies during the breeding season and can increase profit margin when compared to traditional management adopted in southern Brazil.

Replacement of mustard oil cake by urea in short-term strategic feeding of cull ewes to improve body condition and carcass traits

Strategic short-term feeding of culled Malpura ewes (age >6 years, average liveweight 26.8 ± 0.96 kg) was aimed at improving their body condition and increase marketability of their carcass following slaughter. Randomly, 8 out of 40 ewes were slaughtered to study initial (Day 0) carcass traits and the remaining ewes were equally divided into two groups: mustard cake (Control) and urea. They were stall fed with ad libitum guar straw (Cyamopsis tetragonoloba) and concentrate mixture at 25 g/kg liveweight after 4 h of morning grazing in the pasture. The Control group was offered concentrate with solvent extracted mustard cake whereas it was replaced on an equivalent nitrogen (N) basis with urea in the concentrate offered to the other group. Daily feed intake and weekly change in ewe liveweight and body condition score were measured during the 91 days of the experiment. There was no significant (P > 0.05) difference in digestibility of nutrients between the groups. Both groups had similar dry matter and metabolisable energy intake, but the mustard cake group recorded higher (P < 0.05) cumulative weight gain and body condition score. Ruminal fluid samples and blood biochemical measurements were analysed periodically (0, 45 and 91 days), with ruminal fluid samples during the post-feeding hours also analysed. There was periodic variation in rumen pH (P = 0.013), volatile fatty acid (P = 007), total N (P = 0.001) and ammonia-N (P = 0.025) concentration in both groups. Higher post-feeding volatile fatty acid (P = 0.031) and total N (P = 0.003) values were observed in the mustard cake group. Ruminal ciliate protozoal population showed a quadratic response over time after feeding with an initial decline post-grazing, but was not affected by treatment. Similar significant (P < 0.05) improvements in haemoglobin, glucose, total protein, urea and cholesterol levels were evident in both groups at 91 days. Both treatments showed similar improvement in carcass composition, distribution of fat and chemical composition of Longissimus dorsi after 91 days of realimentation compared with initial values. Short-term pre-slaughter feeding of cull ewes improved body condition, carcass traits and composition. Replacement of costly mustard cake with urea in the diet of cull ewes could be a means to improve profitability of this strategic feeding protocol, as well as enhancing their market value.

Strategic Feeding Alternating a 2-months’ Feeding Restriction and a Short Boost of the Feeding Level Increases Conception Rate in Sheep

<p class="1Body">This study aimed to investigate if feeding patterns prior to and after artificial insemination (AI) affect the reproductive performances of ewes. Two breeds were used; the Barbarine (n = 133) and Queue Fine de l’Ouest (QFO; n = 129). For each breed, 2 experimental groups balanced for age and live weight were formed. For 75 days before AI, ewes in treatment High daily grazed for 6 hours and were supplemented with 0.6 kg of concentrate. For those in treatment Low-High, grazing was restricted to 3 hours only. From 21 days before insemination and the following 20 days, feeding pattern for Low-High ewes was switched to the High feeding regime. Changes in live weight and ovarian activity were monitored; conception rate and litter size were recorded. At the end of the restriction period and for both breeds, Low-High ewes reached lower live weights than High ewes (p &lt; 0.05). Prior to AI and for both breeds, Low-High ewes weighed less than those in the High treatment group but no statistical differences were observed. At the end of the restriction period, more QFO ewes were cycling than for the Barbarine breed (75/129 vs. 55/133; p &lt; 0.01). Further, less QFO ewes in the Low-High treatment were cycling than High ewes (30/65 vs. 45/64; p &lt; 0.01). More QFO ewes conceived to AI than Barbarine counterparts (77/112 vs. 73/130; p &lt; 0.05). For both breeds, higher proportions of ewes in the Low-High treatment groups conceived to AI but differences reached statistical significance only for Barbarine breed. Following a food-restriction period between weaning and mating, improved conception rates are achieved if the plane of nutrition is increased few weeks prior to and after AI in comparison to a continuous increase in live weight during the same period.</p>

Strategic Feeding of Ammonium and Metal Ions for Enhanced GLA-Rich Lipid Accumulation inCunninghamella bainieri2A1

Strategic feeding of ammonium and metal ions (Mg2+, Mn2+, Fe3+, Cu2+, Ca2+, Co2+, and Zn2+) for enhanced GLA-rich lipid accumulation inC. bainieri2A1 was established. When cultivated in nitrogen-limited medium, the fungus produced up to 30% lipid (g/g biomass) with 12.9% (g/g lipid) GLA. However, the accumulation of lipid stopped at 48 hours of cultivation although glucose was abundant. This event occurred in parallel to the diminishing activity of malic enzyme (ME), fatty acid synthase (FAS), and ATP citrate lyase (ACL) as well as the depletion of metal ions in the medium. Reinstatement of the enzymes activities was achieved by feeding of ammonium tartrate, but no increment in the lipid content was observed. However, increment in lipid content from 32% to 50% (g/g biomass) with 13.2% GLA was achieved when simultaneous feeding of ammonium, glucose, and metal ions was carried out. This showed that the cessation of lipid accumulation was caused by diminishing activities of the enzymes as well as depletion of the metal ions in the medium. Therefore, strategic feeding of ammonium and metal ions successfully reinstated enzymes activities and enhanced GLA-rich lipid accumulation inC. bainieri2A1.