Livestock breeding and growth
As the intensity of a production system increases, or market specifications tighten, matching pasture supply and quality to livestock needs with more precision makes management decisions more sensitive to pasture deficits and surpluses.
Always consider the costs associated with achieving the target growth pathways, together with returns from expected outcomes (see diagram below).
Nutrition has the biggest impact on breeding and growth within the lifetime of a productive animal. However, choice of animal genetics also impacts on the success of pathways through setting the production and market specific potential of the animals.
Nutrient requirements of an animal are a function of its weight, liveweight gain, sex, physiological state (pregnancy, lactation) and age. Nutrient requirements are also affected by the quality of feed eaten and time spent grazing, climate (particularly too cold or too hot), disease state and degree of social coherence with its colleagues.
Different genetic potential affects nutrient requirements through variation in weight for age, liveweight gain and reproductive capacity. Small effects due to genetic differences in muscling, fatness and fat distribution (marbling) are not taken into account when determining nutrient requirements.
Use a feeding standard based on animal requirements for metabolisable energy (ME) to convert animal nutrient requirements into the amount and quality of feed required is ME is defined as the energy available to an animal after losses due to digestion (faeces, urine, methane).
While methane plays a role in ruminant digestion, it represents a waste in energy and is the most potent greenhouse gas (GHG). Livestock emissions account for about 10% of Australia’s total greenhouse gas (GHG) emissions and about two thirds of the total emissions from agriculture.
The challenge is to reduce methane emissions while increasing productivity and profitability. If the energy used to produce methane can be redirected, animal growth can increase.
Best management practices for production efficiency offer the most practical short-term solution. These practices include improving feed quality and utilisation, turning off stock earlier, culling unproductive animals and improving reproduction rates.
Pasture quality - why ME matters
The ME content of pasture is a good measure of the nutritional value of the pasture in energy terms. The ME per kg of feed dry matter (units are MJ ME/kg DM) is the standard used in Australia. This is termed the ‘energy density’ of a feed and is the main driver of livestock growth per head and (managed appropriately) per hectare.
Energy density of a feed is the major limitation to livestock response. Provide additional important nutrients such as protein and minerals when energy requirements from pastures are achieved. When pastures are of low energy, protein may also be limiting.
Use the relationship between pasture quality and quantity and livestock performance to guide management decisions.
Kwa kuwa kiwango cha uzalishaji cha mifugo huongezeka, au mahitaji ya soko yanazidi kuwa magumu, kulinganisha usambazaji wa malisho na ubora kwa mahitaji ya mifugo kwa usahihi zaidi hufanya maamuzi ya usimamizi yawe nyeti zaidi kwa upungufu wa malisho na ziada. Wakati wote kuzingatia gharama zinazohusiana na kufikia njia ya ukuaji lengo, pamoja na mapato kutoka matokeo ya kutarajiwa (tazama mchoro hapa chini). Chakula kina athari kubwa zaidi juu ya uzazi na ukuaji ndani ya maisha ya mnyama wa uzalishaji. Hata hivyo, uchaguzi wa wanyama genetics pia athari juu ya mafanikio ya njia kwa kuweka uzalishaji na soko maalum uwezo wa wanyama. Mahitaji ya virutubisho ya mnyama ni kazi ya uzito wake, uzito wa kuishi, jinsia, hali ya kisaikolojia (mimba, kunyonyesha) na umri. Mahitaji ya virutubisho pia huathiriwa na ubora wa chakula kinachotumiwa na muda unaotumiwa kuchunga, hali ya hewa (haswa baridi sana au moto sana), hali ya ugonjwa na kiwango cha mshikamano wa kijamii na wenzake. Uwezo tofauti wa maumbile huathiri mahitaji ya virutubisho kupitia tofauti katika uzito kwa umri, kuongezeka kwa uzito wa kuishi na uwezo wa kuzaliana. Athari ndogo kutokana na tofauti za maumbile katika misuli, mafuta na usambazaji wa mafuta (marbling) hazizingatiwi wakati wa kuamua mahitaji ya virutubisho. Kwa mfano, kiwango cha chakula cha wanyama kinachotumiwa kwa ajili ya mahitaji ya chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula cha chakula. Ingawa methani ina jukumu katika kumeng'enya wanyama, inawakilisha kupoteza nishati na ni gesi yenye nguvu zaidi ya chafu (GHG). Uzalishaji wa mifugo ni asilimia 10 ya jumla ya uzalishaji wa gesi za chafu nchini Australia na asilimia 3 ya jumla ya uzalishaji wa kilimo. Changamoto ni kupunguza uzalishaji wa methane wakati wa kuongeza uzalishaji na faida. Ikiwa nishati inayotumiwa kutokeza metani inaweza kuelekezwa upya, ukuzi wa wanyama waweza kuongezeka. Mazoea bora ya usimamizi kwa ufanisi wa uzalishaji kutoa suluhisho la muda mfupi zaidi ya vitendo. Mazoea haya ni pamoja na kuboresha ubora wa chakula na matumizi, kufuta mifugo mapema, kuua wanyama wasio na uzalishaji na kuboresha viwango vya uzazi. Ubora wa malisho - kwa nini ME ni muhimu Maudhui ya ME ya malisho ni kipimo kizuri cha thamani ya lishe ya malisho katika suala la nishati. Kiwango cha MJ kwa kilo ya chakula kavu (vipimo ni MJ MJ kwa kilo ya DM) ni kiwango kinachotumiwa nchini Australia. Hii inaitwa "nishati wiani" ya chakula na ni kichocheo kuu ya ukuaji wa mifugo kwa kichwa na (usimamizi sahihi) kwa hekta. Uwezo wa nishati ya chakula ni kikomo kuu kwa majibu ya mifugo. Kutoa virutubisho vya ziada muhimu kama vile protini na madini wakati mahitaji ya nishati kutoka malisho yanapatikana. Wakati malisho ni ya nishati ya chini, protini pia inaweza kuwa kikomo. Tumia uhusiano kati ya ubora wa malisho na wingi na utendaji wa mifugo kuongoza maamuzi ya usimamizi.